Materials Science › Ceramics and Composites

Advanced ceramic materials synthesis

Works Count: 112173

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Description

This cluster of papers covers advancements in ceramic materials and processing techniques, with a focus on topics such as spark plasma sintering, high-temperature applications, composite materials, nanocrystalline ceramics, oxidation resistance, porous ceramics, and ultra-high temperature ceramics (UHTCs). The research encompasses the synthesis, consolidation, properties, and applications of ceramic materials for various industrial and aerospace uses.

Keywords

Ceramic Materials; Sintering; Spark Plasma Sintering; High-Temperature Applications; Composite Materials; Nanocrystalline Ceramics; Oxidation Resistance; Porous Ceramics; Ultra-High Temperature Ceramics (UHTCs); Material Properties

Ceramic Processing and Sintering

2003-07-31

Mohamed N. Rahaman

Ceramic fabrication processes - an introductory overview synthesis of powders powder characterization science of colloidal processing sol-gel processing powder consolidation and forming of ceramics sintering of ceramics - fundamentals theory … Ceramic fabrication processes - an introductory overview synthesis of powders powder characterization science of colloidal processing sol-gel processing powder consolidation and forming of ceramics sintering of ceramics - fundamentals theory of viscous sintering grain growth and microstructural control liquid-phase sintering problems of sintering densification process variables and densification practice.

Fracture Mechanics of Ceramics

1992-01-01

D. Münz

Compression Strength of Porous Sintered Alumina and Zirconia

1953-02-01

Eugene Ryshkewitch

The influence of controlled porosity on the compression strength of sintered pure alumina and of partly magnesia‐stabilized zirconia was investigated. Bodies with porosities ranging from approximately 3 to 60% by … The influence of controlled porosity on the compression strength of sintered pure alumina and of partly magnesia‐stabilized zirconia was investigated. Bodies with porosities ranging from approximately 3 to 60% by volume were prepared utilizing hydrogen peroxide to induce pore formation. Cubes of approximately 1.2‐cm, unit length were used in testing for compression strength at room temperature. The spatial arrangement of pores in sintered alumina was found to exert an influence, inasmuch as bodies with pores lined parallel to the pressure direction revealed a higher strength than bodies of the same porosity but with pores lined mainly perpendicular to this direction. It was found that an increase of porosity by 10 volume % decreased the strength of both sintered alumina and sintered zirconia by half of their initial respective values.

Oxidation-based materials selection for 2000°C + hypersonic aerosurfaces: Theoretical considerations and historical experience

2004-09-17

Mark M. Opeka , Inna G. Talmy , James A. Zaykoski

Structure and properties of mullite—A review

2007-05-03

H. Schneider , J. Schreuer , Bernd Hildmann

FGM activities in Japan

1997-01-01

M. Koizumi

Factors Affecting Thermal Stress Resistance of Ceramic Materials

1955-01-01

W. D. Kingery

The sources and calculation of thermal stresses are considered, together with the factors involved in thermal stress resistance factors. Properties affecting thermal stress resistance of ceramics are reviewed, and testing … The sources and calculation of thermal stresses are considered, together with the factors involved in thermal stress resistance factors. Properties affecting thermal stress resistance of ceramics are reviewed, and testing methods are considered.

Theory of Mechanical Properties of Ceramic‐Matrix Composites

1991-11-01

W.A. Curtin

A theory is presented to predict the pullout work and ultimate tensile strength of ceramic‐matrix composite (CMC) materials tested under uniaxial tension as functions of the underlying material properties. By … A theory is presented to predict the pullout work and ultimate tensile strength of ceramic‐matrix composite (CMC) materials tested under uniaxial tension as functions of the underlying material properties. By assuming that the fibers fracture independently and that global load redistribution occurs upon fiber fracture, the successive fragmentation of each fiber in the multifiber composite becomes identical to that of a single fiber embedded in a homogeneous large‐failure‐strain matrix, which has recently been solved exactly by the present author. From single‐fiber fragmentation, the multifiber composite distribution of pullout lengths, work of pullout, and ultimate tensile strength are easily obtained. The trends in these composite properties as a function of the statistical fiber strength, the fiber radius and fill fraction, and the sliding resistance τ between the fibers and the matrix easily emerge from this approach. All these properties are proportional to a characteristic gauge length δ c and/or the associated characteristic stress σ, with proportionality constants depending only very weakly on the fiber Weibull modulus: the pullout lengths scale with δ c , the work of pullout scales with σ c δ c , and the ultimate strength scales with σ c . The key length δ c is the generalization of the “critical length,” defined by Kelly for single‐strength fibers, to fibers with a statistical distribution of strengths. The theory also provides an interpretation of fracture‐mirror measurements of pulled‐out fiber strengths so that the in situ key strength σ c and Weibull modulus of the fibers can be determined directly. Comparisons of the theoretical predictions of the ultimate tensile strength to literature data on Nicalon/lithium aluminum silicate (LAS) composites generally show good agreement.

High‐Strength Zirconium Diboride‐Based Ceramics

2004-06-01

Adam L. Chamberlain , William G. Fahrenholtz , Gregory E. Hilmas +1 more

Zirconium diboride (ZrB 2 ) and ZrB 2 ceramics containing 10, 20, and 30 vol% SiC particulates were prepared from commercially available powders by hot pressing. Four‐point bend strength, fracture … Zirconium diboride (ZrB 2 ) and ZrB 2 ceramics containing 10, 20, and 30 vol% SiC particulates were prepared from commercially available powders by hot pressing. Four‐point bend strength, fracture toughness, elastic modulus, and hardness were measured. Modulus and hardness did not vary significantly with SiC content. In contrast, strength and toughness increased as SiC content increased. Strength increased from 565 MPa for ZrB 2 to >1000 MPa for samples containing 20 or 30 vol% SiC. The increase in strength was attributed to a decrease in grain size and the presence of WC.

Rare earth silicate environmental barrier coatings for SiC/SiC composites and Si3N4 ceramics

2005-01-01

Kang N. Lee , Dennis S. Fox , Narottam P. Bansal

Relationships between processing, microstructure and properties of dense and reaction-bonded silicon nitride

1987-09-01

G. Ziegler , J. Heinrich , Gerhard Wtting

Mechanisms of fatigue crack propagation in metals, ceramics and composites: Role of crack tip shielding

1988-08-01

Robert O. Ritchie

Evaluated Material Properties for a Sintered alpha‐Alumina

1997-08-01

Ronald G. Munro

Results of a data evaluation exercise are presented for a particular specification of sintered alpha‐alumina (mass fraction of Al2O3, ≥0.995; relative density (rho/rhotheoretical), ≥0.98; and nominal grain size, 5 μm). … Results of a data evaluation exercise are presented for a particular specification of sintered alpha‐alumina (mass fraction of Al2O3, ≥0.995; relative density (rho/rhotheoretical), ≥0.98; and nominal grain size, 5 μm). A comprehensive set of material property data is established based on published physical, mechanical, and thermal properties of alumina specimens that conform to the constraints of the material specification. The criteria imposed on the properties are that the values should be derived from independent experimental studies, that the values for physically related properties should be mutually self‐consistent, and that the sets of values should be compatible with established material property relations. The properties assessed in this manner include crystallography, thermal expansion, density, sound velocity, elastic modulus, shear modulus, Poisson's ratio, bulk modulus, compressive strength, flexural strength, Weibull characteristic strength, Weibull modulus, tensile strength, hardness, fracture toughness, creep rate, creep rate stress exponent, creep activation energy, friction coefficient, wear coefficient, melting point, specific heat, thermal conductivity, and thermal diffusivity.

A simple way to make tough ceramics

1990-10-01

W.J. Clegg , K. Kendall , Neil McN. Alford +2 more

Corrosion of Silicon‐Based Ceramics in Combustion Environments

1993-01-01

Nathan Jacobson

Silicon‐based ceramics and composites are prime candidates for heat engine and heat exchanger structural components. In such applications these materials are exposed to combustion gases and deposit‐forming corrodents. In this … Silicon‐based ceramics and composites are prime candidates for heat engine and heat exchanger structural components. In such applications these materials are exposed to combustion gases and deposit‐forming corrodents. In this paper combustion environments are defined for various applications. These environments lead to five main types of corrosive degradation: passive oxidation, deposit‐induced corrosion, active oxidation, scale/substrate interactions, and scale volatility. Each of these is discussed in detail. The key issues in oxidation mechanisms of high‐purity silicon carbide (SiC) and silicon nitride (Si 3 N 4 ) in pure oxygen are discussed. The complicating factors due to the actual combustion environment and commercial materials are discussed. These discussions include secondary elements in the ceramics; additional oxidants, such as water and carbon dioxide (CO 2 ); combustion environment impurities; long‐term oxidation effects; and thermal cycling. Active oxidation is expected in a limited number of combustion situations, and the active‐to‐passive transition is discussed. At high temperatures the limiting factors are scale melting, scale volatility, and scale/substrate interactions. Deposit‐induced corrosion is discussed, primarily for sodium sulfate (Na 2 SO 4 ), but also for vanadate and oxide‐slag deposits as well. In applying ceramics in combustion environments it is essential to be aware of these corrosion routes and how they affect the performance of a component.

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Transformation Toughening in Zirconia‐Containing Ceramics

2000-03-01

R. H. J. Hannink , Patrick Kelly , Barry C. Muddle

The recognition of the potential for enhanced fracture toughness that can be derived from controlled, stress‐activated tetragonal ( t ) to monoclinic ( m ) transformation in ZrO 2 ‐based … The recognition of the potential for enhanced fracture toughness that can be derived from controlled, stress‐activated tetragonal ( t ) to monoclinic ( m ) transformation in ZrO 2 ‐based ceramics ushered in a new era in the development of the mechanical properties of engineering ceramics and provided a major impetus for broader‐ranging research into the toughening mechanisms available to enhance the fracture properties of brittle‐matrix materials. ZrO 2 ‐based systems have remained a major focal point for research as developments in understanding of the crystallography of the t → m transformation have led to more‐complete descriptions of the origins of transformation toughening and definition of the features required of a transformation‐toughening system. In parallel, there have been significant advances in the design and control of microstructure required to optimize mechanical properties in materials developed commercially. This review concentrates on the science of the t → m transformation in ZrO 2 and its application in the modeling of transformation‐toughening behavior, while also summarizing the microstructural control needed to use the benefits in ZrO 2 ‐toughened ceramics.

The Occurrence of Metastable Tetragonal Zirconia as a Crystallite Size Effect

1965-04-01

R. C. Garvie

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Occurrence of Metastable Tetragonal Zirconia as a Crystallite Size EffectRonald C. GarvieCite this: J. Phys. Chem. 1965, 69, 4, 1238–1243Publication Date (Print):April 1, 1965Publication History Published … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Occurrence of Metastable Tetragonal Zirconia as a Crystallite Size EffectRonald C. GarvieCite this: J. Phys. Chem. 1965, 69, 4, 1238–1243Publication Date (Print):April 1, 1965Publication History Published online1 May 2002Published inissue 1 April 1965https://pubs.acs.org/doi/10.1021/j100888a024https://doi.org/10.1021/j100888a024research-articleACS PublicationsRequest reuse permissionsArticle Views4685Altmetric-Citations1315LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access options Get e-Alerts

Mechanical, Thermal, and Oxidation Properties of Refractory Hafnium and zirconium Compounds

1999-10-01

Mark M. Opeka , Inna G. Talmy , Eric Wuchina +2 more

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Evaluation of ultra-high temperature ceramics foraeropropulsion use

2002-01-01

Stanley R. Levine , Elizabeth J. Opila , Michael C. Halbig +3 more

A fracture mechanics analysis of indentation-induced Palmqvist crack in ceramics

1983-05-01

Koichi Niihara

Design, preparation and properties of non-oxide CMCs for application in engines and nuclear reactors: an overview

2003-10-09

R. Naslain

Handbook of SiC properties for fuel performance modeling

2007-05-11

Lance L. Snead , Takashi Nozawa , Yutai Katoh +3 more

1000 at 1000: The effect of electric field and pressure on the synthesis and consolidation of materials: a review of the spark plasma sintering method

2020-07-10

Zuhair A. Munir

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Erratum: Modeling solid-state chemistry: Interatomic potentials for multicomponent systems

1990-02-15

J. Tersoff

TersoffDue to a typesetting error, values for the parameters 8 and d for carbon were incorrectly transcribed in Table I.The actual values, which were given correctly in Ref. 2, are … TersoffDue to a typesetting error, values for the parameters 8 and d for carbon were incorrectly transcribed in Table I.The actual values, which were given correctly in Ref. 2, are 8 =3.4674X10 eV and d=4.3484.Fortunately,

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Strong, lightweight, and recoverable three-dimensional ceramic nanolattices

2014-09-11

Lucas R. Meza , Satyajit Das , Julia R. Greer

Ceramics have some of the highest strength- and stiffness-to-weight ratios of any material but are suboptimal for use as structural materials because of their brittleness and sensitivity to flaws. We … Ceramics have some of the highest strength- and stiffness-to-weight ratios of any material but are suboptimal for use as structural materials because of their brittleness and sensitivity to flaws. We demonstrate the creation of structural metamaterials composed of nanoscale ceramics that are simultaneously ultralight, strong, and energy-absorbing and can recover their original shape after compressions in excess of 50% strain. Hollow-tube alumina nanolattices were fabricated using two-photon lithography, atomic layer deposition, and oxygen plasma etching. Structures were made with wall thicknesses of 5 to 60 nanometers and densities of 6.3 to 258 kilograms per cubic meter. Compression experiments revealed that optimizing the wall thickness-to-radius ratio of the tubes can suppress brittle fracture in the constituent solid in favor of elastic shell buckling, resulting in ductile-like deformation and recoverability.

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Structures and transformation mechanisms of the η, γ and θ transition aluminas

1991-10-01

Ruhong Zhou , Robert L. Snyder

Silicon Nitride and Related Materials

2000-02-01

Frank L. Riley

Silicon nitride has been researched intensively, largely in response to the challenge to develop internal combustion engines with hot‐zone components made entirely from ceramics. The ceramic engine programs have had … Silicon nitride has been researched intensively, largely in response to the challenge to develop internal combustion engines with hot‐zone components made entirely from ceramics. The ceramic engine programs have had only partial success, but this research effort has succeeded in generating a degree of understanding of silicon nitride and of its processing and properties, which in many respects is more advanced than of more widely used technical ceramics. This review examines from the historical standpoint the development of silicon nitride and of its processing into a range of high‐grade ceramic materials. The development of understanding of microstructure–property relationships in the silicon nitride materials is also surveyed. Because silicon nitride has close relationships with the SiAlON group of materials, it is impossible to discuss the one without some reference to the other, and a brief mention of the development of the SiAlONs is included for completeness.

Polymer‐Derived Ceramics: 40 Years of Research and Innovation in Advanced Ceramics

2010-06-08

Paolo Colombo , Gabriela Mera , Ralf Riedel +1 more

Preceramic polymers were proposed over 30 years ago as precursors for the fabrication of mainly Si‐based advanced ceramics, generally denoted as polymer‐derived ceramics (PDCs). The polymer to ceramic transformation process … Preceramic polymers were proposed over 30 years ago as precursors for the fabrication of mainly Si‐based advanced ceramics, generally denoted as polymer‐derived ceramics (PDCs). The polymer to ceramic transformation process enabled significant technological breakthroughs in ceramic science and technology, such as the development of ceramic fibers, coatings, or ceramics stable at ultrahigh temperatures (up to 2000°C) with respect to decomposition, crystallization, phase separation, and creep. In recent years, several important advances have been achieved such as the discovery of a variety of functional properties associated with PDCs. Moreover, novel insights into their structure at the nanoscale level have contributed to the fundamental understanding of the various useful and unique features of PDCs related to their high chemical durability or high creep resistance or semiconducting behavior. From the processing point of view, preceramic polymers have been used as reactive binders to produce technical ceramics, they have been manipulated to allow for the formation of ordered pores in the meso‐range, they have been tested for joining advanced ceramic components, and have been processed into bulk or macroporous components. Consequently, possible fields of applications of PDCs have been extended significantly by the recent research and development activities. Several key engineering fields suitable for application of PDCs include high‐temperature‐resistant materials (energy materials, automotive, aerospace, etc.), hard materials, chemical engineering (catalyst support, food‐ and biotechnology, etc.), or functional materials in electrical engineering as well as in micro/nanoelectronics. The science and technological development of PDCs are highly interdisciplinary, at the forefront of micro‐ and nanoscience and technology, with expertise provided by chemists, physicists, mineralogists, and materials scientists, and engineers. Moreover, several specialized industries have already commercialized components based on PDCs, and the production and availability of the precursors used has dramatically increased over the past few years. In this feature article, we highlight the following scientific issues related to advanced PDCs research: (1) General synthesis procedures to produce silicon‐based preceramic polymers. (2) Special microstructural features of PDCs. (3) Unusual materials properties of PDCs, that are related to their unique nanosized microstructure that makes preceramic polymers of great and topical interest to researchers across a wide spectrum of disciplines. (4) Processing strategies to fabricate ceramic components from preceramic polymers. (5) Discussion and presentation of several examples of possible real‐life applications that take advantage of the special characteristics of preceramic polymers. Note : In the past, a wide range of specialized international symposia have been devoted to PDCs, in particular organized by the American Ceramic Society, the European Materials Society, and the Materials Research Society. Most of the reviews available on PDCs are either not up to date or deal with only a subset of preceramic polymers and ceramics (e.g., silazanes to produce SiCN‐based ceramics). Thus, this review is focused on a large number of novel data and developments, and contains materials from the literature but also from sources that are not widely available.

Microstructural Design of Toughened Ceramics

1991-02-01

Paul Becher

The fracture toughness of ceramics can be improved by the incorporation of a variety of discontinuous, elastic reinforcing phases that generate a crack‐bridging zone. Recent models of toughening by crack‐bridging … The fracture toughness of ceramics can be improved by the incorporation of a variety of discontinuous, elastic reinforcing phases that generate a crack‐bridging zone. Recent models of toughening by crack‐bridging processes are discussed and used to describe the behavior observed in whisker‐reinforced ceramics. The toughening response in ceramics reinforced with other types of discontinuous reinforcements is then considered (e.g., matrix and second‐phase platelike grains, elongated matrix grains, and grain‐size effects in noncubic matrices). It is shown that crack‐bridging toughening processes can be combined with other bridging mechanisms and with other toughening mechanisms (e.g., transformation toughening) to achieve synergistic effects. From these discussions, it is shown that the design of the toughened materials relies heavily on the control of the material properties and microstructural components influencing the toughening behavior to optimize the contributions of both the reinforcing phase and the matrix.

A Critical Evaluation of Indentation Techniques for Measuring Fracture Toughness: II, Strength Method

1981-09-01

P. Chantikul , G. R. Anstis , Brian R. Lawn +1 more

An examination is made of the sharp‐indentation technique of strength‐test precracking for toughness evaluation. The experimental approach follows that proposed by other workers but the theoretical analysis contains one vital … An examination is made of the sharp‐indentation technique of strength‐test precracking for toughness evaluation. The experimental approach follows that proposed by other workers but the theoretical analysis contains one vital new feature; the residual‐stress term discussed in Part I of this study is now introduced explicitly into the strength formulation. This modification overcomes a major systematic discrepancy evident in the previous models and at the same time, by virtue of attendant changes in the nature of the crack stability prior to attaining a failure configuration, eliminates the need for frac‐tographic measurements. Other advantages are also apparent, notably an insensitivity to postindentation radial crack extension. The main disadvantage is that only one result is obtained per specimen. Indentation/strength data from ceramics listed in Part I confirm the essential features of the theory and provide a suitable calibration factor. The method has special application to those materials which do not necessarily produce a well‐defined radial crack pattern, in which case an “effective” K c appropriate to fracture properties at the flaw level is obtained.

Mechanics of Transformation‐Toughening in Brittle Materials

1982-05-01

Robert M. McMeeking , A.G. Evans

Particles which undergo a stress‐induced martensitic transformation are known to toughen certain brittle materials. The enhanced toughness can be considered to originate from the residual strain fields which develop following … Particles which undergo a stress‐induced martensitic transformation are known to toughen certain brittle materials. The enhanced toughness can be considered to originate from the residual strain fields which develop following transformation and tend to limit the crack opening. The increased toughness can estimated from the crack‐tip stress‐intensity change induced by the transformation of a volume of material near the crack tip. It is found that the initial zone, prior to crackgrowth, provides no change in stress intensity. As the crack grows, the zone (associated with a positive transformation strain) induces a stress‐intensity reduction that rises to a maximum level after some crack propagation. The influence of particle‐size distribution on the stress‐intensity reduction is also discussed.

Powder Processing Science and Technology for Increased Reliability

1989-01-01

Fred F. Lange

Issues concerning powder consolidation methods compatible with the colloidal approach and issues associated with other powder processing steps, viz., densification and microstructural control, are presented with regard to research directions … Issues concerning powder consolidation methods compatible with the colloidal approach and issues associated with other powder processing steps, viz., densification and microstructural control, are presented with regard to research directions leading to more reliable ceramics.

Fracture Toughness Determinations by Indentation

1976-07-01

A.G. Evans , E.A. Charles

Refractory Diborides of Zirconium and Hafnium

2007-05-01

William G. Fahrenholtz , Gregory E. Hilmas , Inna G. Talmy +1 more

This paper reviews the crystal chemistry, synthesis, densification, microstructure, mechanical properties, and oxidation behavior of zirconium diboride (ZrB2) and hafnium diboride (HfB2) ceramics. The refractory diborides exhibit partial or complete … This paper reviews the crystal chemistry, synthesis, densification, microstructure, mechanical properties, and oxidation behavior of zirconium diboride (ZrB2) and hafnium diboride (HfB2) ceramics. The refractory diborides exhibit partial or complete solid solution with other transition metal diborides, which allows compositional tailoring of properties such as thermal expansion coefficient and hardness. Carbothermal reduction is the typical synthesis route, but reactive processes, solution methods, and pre-ceramic polymers can also be used. Typically, diborides are densified by hot pressing, but recently solid state and liquid phase sintering routes have been developed. Fine-grained ZrB2 and HfB2 have strengths of a few hundred MPa, which can increase to over 1 GPa with the addition of SiC. Pure diborides exhibit parabolic oxidation kinetics at temperatures below 1100°C, but B2O3 volatility leads to rapid, linear oxidation kinetics above that temperature. The addition of silica scale formers such as SiC or MoSi2 improves the oxidation behavior above 1100°C. Based on their unique combination of properties, ZrB2 and HfB2 ceramics are candidates for use in the extreme environments associated with hypersonic flight, atmospheric re-entry, and rocket propulsion.

Stabilized zirconia as a structural ceramic: An overview☆

2007-07-13

J. Robert Kelly , Isabelle Denry

Direct Observation and Analysis of Indentation Cracking in Glasses and Ceramics

1990-04-01

Robert F. Cook , George M. Pharr

A review of the observations of indentation‐induced fracture suggests that there is no simple generalization which may be made concerning crack initiation sequences. Here, we investigate the material dependence of … A review of the observations of indentation‐induced fracture suggests that there is no simple generalization which may be made concerning crack initiation sequences. Here, we investigate the material dependence of the initiation sequence of indentation cracks (cone, radial, median, half‐penny, and lateral) using an inverted tester allowing simultaneous viewing of the fracture process and measurement of the indeter load and displacement during contact. Two normal glasses, two anomalous glasses, and seven crystalline materials are examined. Key results include (i) direct evidence that the surface traces of cracks observed at indentation contacts are those of radial cracks, rather than median‐nucleated half‐penny cracks (at least for peak contact loads <40 N) and (ii) that, in crystalline materials, radial cracks form almost immediately on loading of the indenter, in anomalous glasses at somewhat greater loads, but in normal glasses during unloading. A detailed consideration of the stress fields arising during indentation contact predicts material‐dependent initiation sequences, in agreement with observations, particularly those of radial crack formation on loading for materials with large modulus‐to‐hardness ratios. In addition, a new, unexplored crack system is demonstrated, the shallow lateral cracks, which appear to be responsible for material removal at sharp contacts.

Perspective on the Development of High‐Toughness Ceramics

1990-02-01

A.G. Evans

Spark Plasma Sintering of Alumina

2002-08-01

Zhijian Shen , Mats Johnsson , Zhe Zhao +1 more

A systematic study of various spark plasma sintering (SPS) parameters, namely temperature, holding time, heating rate, pressure, and pulse sequence, was conducted to investigate their effect on the densification, grain‐growth … A systematic study of various spark plasma sintering (SPS) parameters, namely temperature, holding time, heating rate, pressure, and pulse sequence, was conducted to investigate their effect on the densification, grain‐growth kinetics, hardness, and fracture toughness of a commercially available submicrometer‐sized Al 2 O 3 powder. The obtained experimental data clearly show that the SPS process enhances both densification and grain growth. Thus, Al 2 O 3 could be fully densified at a much lower temperature (1150°C), within a much shorter time (minutes), than in more conventional sintering processes. It is suggested that the densification is enhanced in the initial part of the sintering cycle by a local spark‐discharge process in the vicinity of contacting particles, and that both grain‐boundary diffusion and grain‐boundary migration are enhanced by the electrical field originating from the pulsed direct current used for heating the sample. Both the diffusion and the migration that promote the grain growth were found to be strongly dependent on temperature, implying that it is possible to retain the original fine‐grained structure in fully densified bodies by avoiding a too high sintering temperature. Hardness values in the range 21–22 GPa and fracture toughness values of 3.5 ± 0.5 MPa·m 1/2 were found for the compacts containing submicrometer‐sized Al 2 O 3 grains.

Ultrastructure processing of advanced ceramics

1989-02-01

K.‐H. Zum Gahr

New Design Concept of Structural Ceramics

1991-01-01

Koichi Niihara

Ceramic nanocomposites can be divided into three categories: intergranular nanocomposite, intergranular nanocomposite and nano/nano composite. The intra- and intergranular nanocomposites were found to show the two to five times higher … Ceramic nanocomposites can be divided into three categories: intergranular nanocomposite, intergranular nanocomposite and nano/nano composite. The intra- and intergranular nanocomposites were found to show the two to five times higher toughness and strength at room temperature than those of monolithic materials. The hardness, toughness, strength and fracture resistance for creep and fatigue at high temperatures as well as the thermal shock fracture resistance were also strongly improved for these composites. On the other hand, the new function such as machinability and superplasticity was observed for the nano/nano composites. The fabrication processes of these nanocomposites by sintering methods, micro and nanostructure observations, improvements of mechanical properties were reviewed and the roles of the nano-size dispersoids were discussed. Finally the new approach on structural materials design will be given.

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Ultra-high temperature ceramics: Materials for extreme environments

2016-10-20

William G. Fahrenholtz , Gregory E. Hilmas

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The effect of electric field and pressure on the synthesis and consolidation of materials: A review of the spark plasma sintering method

2006-02-01

Zuhair A. Munir , Umberto Anselmi‐Tamburini , Manshi Ohyanagi

Sialons and related nitrogen ceramics

1976-06-01

K. H. Jack

Introduction to Ceramics

1977-03-01

W. D. Kingery , H. Kent Bowen , D. R. Uhlmann +1 more

Heterostructured materials

2022-09-17

Yuntian Zhu , Xiaolei Wu

Heterostructured (HS) materials are a new class of materials that are composed of heterogeneous zones with dramatically different (>100 %) mechanical or physical properties. The interactive coupling between these heterogeneous … Heterostructured (HS) materials are a new class of materials that are composed of heterogeneous zones with dramatically different (>100 %) mechanical or physical properties. The interactive coupling between these heterogeneous zones produces a synergistic effect in which the integrated property exceeds the prediction by the rule-of-mixtures. HS materials possess superior mechanical or physical properties that are not achievable by their conventional homogenous counterparts. This review focuses primarily on structural HS materials, whose superior mechanical properties are enabled by a new scientific principle: hetero-deformation induced (HDI) strengthening and HDI work hardening. Geometrically necessary dislocations (GNDs) in the soft zones pile up and accumulate near the zone boundaries, producing back stress in the soft zones and forward stress in the hard zones, which collectively produces the HDI stress. HS materials have a unique deformation behavior: formation of dispersive microscopic strain bands, which helps to distribute plastic strain over the whole gauge length, increasing uniform elongation. They can be readily produced using conventional industrial technologies and facilities at large scale and low cost. The superior properties, new materials science and great application potentials are driving the fast development of the HS materials field. This review is meant to introduce students and researchers to this emerging field, and to serve as an authoritative reference on HS materials.

Mechanical Testing and Evaluation

2000-01-01

Howard Kuhn , Dana Medlin

Introduction to the Mechanical Behavior of Metals and Nonmetallic Materials Mechanical Testing of Polymers and Ceramics Mechanical Properties and Testing for Design Mechanical Testing for Metalworking processes Testing Machines and … Introduction to the Mechanical Behavior of Metals and Nonmetallic Materials Mechanical Testing of Polymers and Ceramics Mechanical Properties and Testing for Design Mechanical Testing for Metalworking processes Testing Machines and Strain Sensors Accreditation of Mechanical-Testing Laboratories Tension, Compression, Bend, and Shear Testing Hardness Testing Friction, Wear, and Surface Testing Creep and Stress-Relaxtion Testing High-Strain-Rate Testing Impact-Toughness Testing and Fracture Mechanics Fatigue Testing Component Testing Property-Comparison Tables Glossary of Terms Index.

Coefficient of Thermal Expansion of Si3N4 via Neutron Diffraction

2025-06-25

Geoffrey A. Swift | International Journal of Thermophysics

Investigation of the Thermal Stability of High Energy Ball Milled SiC Nanoparticles Using Thermogravimetric and Differential Thermal Analysis

2025-06-25

M. Sekar , Vinodhkumar Balakrishna , Vivek Rajavelu +1 more | Periodica Polytechnica Chemical Engineering

In this paper, an attempt has been made to analyze the thermal stability of silicon carbide (SiC) particles using thermogravimetric and differential thermal analysis (TGA/DTA). The SiC particles were made … In this paper, an attempt has been made to analyze the thermal stability of silicon carbide (SiC) particles using thermogravimetric and differential thermal analysis (TGA/DTA). The SiC particles were made by using a high-energy ball milling (HEBM) process to break down micro-sized particles into nano-sized ones. The HEBM was conducted over 60 h, with samples collected at intervals of 15, 30, 45, and 60 h. The samples were further characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) to examine changes in crystallinity and particle morphology. XRD analysis revealed shifts in peak positions, indicating structural changes induced by the milling process. SEM and TEM analyses showed a more homogeneous structure in the milled samples. TGA/DTA analysis demonstrated that nanosized SiC particles exhibited reduced thermal stability. Milling for a longer time caused mass loss to increase, ranging from 2% to 4.24%, at temperatures from 30 °C to 1000 °C and a heating rate of 20 °C/min in a nitrogen atmosphere. These findings show that nanosized SiC particles could be useful in high-temperature situations, especially in fields that need materials that are very stable at high temperatures.

Advancements in Mercury Intrusion Porosimetry for Pore Structure Analysis of Cement-based Materials

2025-06-24

Z. Zhang | Journal of Engineering Research and Reports

MIP remains indispensable for pore structure analysis due to its precision and broad measurement range. However, its integration with XCT represents a breakthrough, offering a holistic view of cement-based materials' … MIP remains indispensable for pore structure analysis due to its precision and broad measurement range. However, its integration with XCT represents a breakthrough, offering a holistic view of cement-based materials' porosity. In the determination of pore characteristics of porous materials, mercury pressure method can measure pore size up to 5 orders of magnitude, with a minimum of about 2 nm and a maximum pore size of hundreds of microns. Combining MIP and XCT overcomes the individual limitations of each technique, providing an unprecedented, multi-scale, and 3D view of the pore structure. This leads to significantly more accurate microstructure-property relationships, enabling better durability prediction, material design, and fundamental understanding of cement-based materials. into exploring pore distribution patterns within cement-based porous matrices. Future research should focus on minimizing pressure-induced artifacts and refining combined methodologies to further advance microstructure characterization and application-oriented material optimization.

Effect of carbothermal reduction on microstructure, oxygen concentration, and thermal conductivity of Si3N4 ceramics

2025-06-24

Binbin Fan , Tianci Wang , Bohan Wang +7 more | Journal of the American Ceramic Society

Abstract This study elucidates the role of carbothermal reduction in tailoring the microstructure, oxygen concentration, and thermal conductivity of Si₃N₄ ceramics synthesized via two‐step gas pressure sintering. Carbon incorporation promoted … Abstract This study elucidates the role of carbothermal reduction in tailoring the microstructure, oxygen concentration, and thermal conductivity of Si₃N₄ ceramics synthesized via two‐step gas pressure sintering. Carbon incorporation promoted the evolution of elongated β‐Si₃N₄ grains and altered the nature of intergranular phases. Electron energy loss spectroscopy (EELS) revealed substantial lattice oxygen depletion in C‐doped specimens, alongside a pronounced diffusion gradient from grain interiors to boundaries in undoped samples—indicative of oxygen redistribution driven by concentration gradients. These modifications, combined with thinner grain boundary films and a reduced volume fraction of secondary phases, substantially boosted heat conduction. As a result, the thermal conductivity of the C‐doped ceramic reached 97 W·m⁻¹·K⁻¹, representing a 54% enhancement over its undoped counterpart. This work underscores the efficacy of carbothermal reduction as a microstructural and chemical engineering approach to advance the thermal performance of Si₃N₄ ceramics for next‐generation thermal management technologies.

Evaluation of aluminoborophosphate enamel coating for application as a thermal barrier to aluminum alloys

2025-06-24

Francieli Gonçalves Franceschini , Henrique Borba Modolon , F. Raupp-Pereira +3 more | Journal of Materials Science

Comparing the Effect of Precrystallization or Postcrystallization Adjustments on Fatigue Behavior of Lithium Disilicate‐Based Ceramics

2025-06-23

ABDEL RAHIM MOHAMAD ABDEL SALAM SULEIMAN , Luiza Freitas Brum Souza , Vinícius Felipe Wandscher +2 more | Journal of Biomedical Materials Research Part B Applied Biomaterials

The aim of this study is to assess the effect of the timing of adjustment on the fatigue flexural behavior and surface characteristics of lithium disilicate-based ceramics. Discs (Ø = … The aim of this study is to assess the effect of the timing of adjustment on the fatigue flexural behavior and surface characteristics of lithium disilicate-based ceramics. Discs (Ø = 15 and 1.2 mm thickness) of four lithium disilicate-based ceramics (IPS e.max CAD, Ivoclar AG; Rosetta SM, HASS Corp; T-Lithium, Shenzhen Upcera Dental Technology Co Ltd; Goozir, Shenzhen Yurucheng Dental Materials Co) were obtained and randomly allocated into three groups based on the timing of adjustment factor: CTRL-directly crystallized without any additional treatment; PRE-subjected to adjustment precrystallization; POST-adjusted postcrystallization. The specimens underwent cyclic fatigue biaxial piston-on-three-balls flexural testing (n = 10; 20 Hz frequency, 10,000 cycles per step, initial stress of 100 MPa, and step-size of 25 MPa). Fatigue flexural strength (FFS) and the number of cycles for fatigue failure (CFF) were recorded and submitted to factorial (two-way analysis of variance [ANOVA]), survival (Kaplan-Meier and Mantel-Cox tests) and Weibull analysis. Surface roughness data were collected and submitted to two-way ANOVA and Tukey's posthoc tests. Fractographic and topographic features were descriptively and qualitatively analyzed. Both the adjustment (p < 0.0001 and F = 49.18) and material (p < 0.0001 and F = 11.99) factors showed a statistically significant impact on the FFS and CFF, as did their interaction (p = 0.03 and F = 2.51), indicating higher values for the CTRL and PRE groups compared to the POST group, and for the T-LITHIUM, EMAX, and GOOZIR materials compared to ROSETTA. Regarding the Weibull modulus, all groups showed similar statistical values. Surface roughness was also influenced by both factors (p < 0.05-PRE > POST > CTRL). ROSETTA exhibited higher Ra values than EMAX and higher Rz values than both EMAX and TALMAX. Fractures always originated at surface defects in the tensile stress concentration region. Topographic features revealed prominent scratches in the PRE groups due to adjustments, smoother scratches in the POST groups, and polishing scratches in the CTRL groups. Consequently, while precrystallization adjustment increases the roughness of lithium disilicate-based ceramics, it does not affect their fatigue behavior. Meanwhile, postcrystallization adjustment deleteriously affects the flexural fatigue strength. Thus, if needed, adjustments should be made precrystallization of lithium disilicate-based ceramics. Also, different lithium disilicate-based ceramics exhibit varying fatigue behaviors; in this study, Rosetta SM showed reduced properties compared to T-Lithium CAD, IPS e.max CAD, and Goozir Lithium Disilicate.

Tailoring of Thermosensitive Ultrasonic and Mechanical Properties of ε-Fe3N

2025-06-23

Ruchi Srivastava , Singh Rb , Giridhar Mishra | VNU Journal of Science Mathematics - Physics

This work examines the mechanical and thermal properties of ε-Fe3N, a material with a hexagonal crystal structure (hcp). The ε-Fe3N's hcp structure allows for a broad range of nitrogen stoichiometry, … This work examines the mechanical and thermal properties of ε-Fe3N, a material with a hexagonal crystal structure (hcp). The ε-Fe3N's hcp structure allows for a broad range of nitrogen stoichiometry, which can be adjusted to enhance its properties. Fe3N is a promising contender for upcoming energy technologies due to its unique properties, including high catalytic activity and thermal stability. Its structure contributes to efficient heat dissipation and enhanced mechanical behavior at elevated temperatures. Here, the hcp ε-Fe3N has been characterized by a potential model. First, we computed higher-order elastic constants (HOECs) and then mechanical properties using the HOECs constants at various temperatures. The material's mechanical characteristics give information about its inherent qualities and stability. Additionally, we have determined the specific heat, thermal conductivity, Debye temperature, and ultrasonic velocities at various temperatures. Finally, all relevant parameters are used to determine the ultrasonic attenuation. The results obtained are consistent with the information found in the other works. Keywords: HOECs, mechanical and thermal properties, attenuation.

Improved Properties of Ceramic Shells by Optimizing the Surface Composition from Lanthanide-Based Composites

2025-06-23

Minghui Li , Jianbo Yu , Xia Li +3 more | Coatings

The precision casting of nickel-based single-crystal superalloys imposes stringent requirements on the high-temperature stability and chemical inertness of ceramic shell face coats. To address the issue of traditional EC95 shells … The precision casting of nickel-based single-crystal superalloys imposes stringent requirements on the high-temperature stability and chemical inertness of ceramic shell face coats. To address the issue of traditional EC95 shells (95% Al2O3–5% SiO2) being prone to react with the alloy melt at elevated temperatures, thereby inducing casting defects, this study proposes a lanthanide oxide-based ceramic face coat material. Three distinct powders—LaAlO3 (LA), LaAlO3/La2Si2O7 (LAS), and LaAl11O18/La2Si2O7/Al2O3 (LA11S)—are successfully prepared through solid-phase sintering of the La2O3-Al2O3-SiO2 ternary system. Their slurry properties, shell sintering processes, and high-temperature performance are systematically investigated. The results demonstrate that optimal slurry coating effectiveness is achieved when LA powder is processed with a liquid-to-powder ratio of 3:1 and a particle size of 300 mesh. While LA shells show no cracking at 1300 °C, their face coats fail above 1400 °C due to the formation of a La2Si2O7 phase. In contrast, LAS and LA11S shells suppress cracking through the La2Si2O7 and LaAl11O18 phases, respectively, exhibiting exceptionally high-temperature stability at 1400 °C and 1500 °C. All three shells meet the high-temperature strength requirements for CMSX-4 single-crystal alloy casting. Interfacial reaction analysis and Gibbs free energy calculations reveal that Al2O3-forming reactions occur between the novel shells and alloy melt, accompanied by minor dissolution erosion without other chemical side reactions. This work provides a high-performance face coat material solution for investment casting of nickel-based superalloys.

Contribution to understanding the theoretical basis of master sintering curve and its numerical approaches

2025-06-22

Jishi Du , Zhao Zhang , Xianhang Zhao +5 more | Journal of the American Ceramic Society

Abstract Contributing to understanding the theoretical basis of master sintering curve (MSC) and its numerical approaches, this paper reorganizes the derivation of MSC theory and presents the numerical approaches of … Abstract Contributing to understanding the theoretical basis of master sintering curve (MSC) and its numerical approaches, this paper reorganizes the derivation of MSC theory and presents the numerical approaches of linear regression. The confidence interval of the apparent activation energy of sintering Q can be obtained by the linear regression approaches, which is useful in compariso. The densification process of a 95 wt% alumina ceramic during sintering is analyzed by different approaches. For the usual approach of MSC that assumes Q to be a constant, the value of Q calculated by the trial solution falls in the 95% and 90% confidence intervals of Q calculated by the linear regression approach. For the differentiating approach that assumes Q to be a function of density, there is little difference between these two curves calculated by the linear regression approach and the trial solution. At last, the micro‐process of densification during sintering and the applicability of MSC theory are discussed. In the final stage of sintering, the diffusivity of the enclosed gas contributes much more to Q , making Q seem larger, so the differentiating approach is more suitable for analyzing the densification process of a large density interval.

Achieving high-strength, hierarchically porous SiC ceramics with micron-scale periodic architecture via vat photopolymerization

2025-06-22

Keqiang Zhang , Zijian Zhang , Wanyu Li +3 more | Virtual and Physical Prototyping

Carbochlorination mechanism of mullite in high-alumina fly ash: density functional theory simulations

2025-06-21

Long Wang , Zimu Zhang , Zhao Xinxin +5 more | Fuel

Formation of Layered Structure in Ceramics Based on Alumina Nanopowder Under Effect of Induction Heating

2025-06-20

L.L. Sartinska | Powders

The effect of induction heating on alumina ceramics and alumina ceramic composites based on α-Al2O3 nanopowders (additives: SiC, Si3N4, SiO2, ZrO2) has been examined. Various factors such as the structure, … The effect of induction heating on alumina ceramics and alumina ceramic composites based on α-Al2O3 nanopowders (additives: SiC, Si3N4, SiO2, ZrO2) has been examined. Various factors such as the structure, grain size, distribution of elements, hardness, fracture toughness, and wear rate of hot-pressed ceramic materials were assessed. Despite achieving improved densification of alumina ceramics at a higher temperature of 1720 °C, there is a consistent trend toward a decline in hardness and fracture toughness. Heating at lower temperatures of 1300–1500 °C results in the development of a strengthened surface layer with a fine-grained structure enriched with carbon. Therefore, the wear rate behavior of such ceramics differs from the behavior of samples made at higher temperatures of 1600–1720 °C. This fact indicates the presence of a non-thermal microwave effect of induction heating. The incorporation of additives to alumina leads to the formation of novel structures with altered crack propagation patterns. The optimal ceramic composite, containing 5 wt. % SiC, displayed superior hardness and the lowest wear rate when compared to pure alumina ceramics. Across all investigated composites, a short dwell time at 1700 °C results in an enhancement of the mechanical properties.

Silicon Oxycarbide Thin Films Produced by Hydrogen-Induced CVD Process from Cyclic Dioxa-Tetrasilacyclohexane

2025-06-19

A. Walkiewicz‐Pietrzykowska , Krzysztof Jankowski , Jan Kurjata +4 more | Materials

Silicon oxycarbide coatings are the subject of research due to their exceptional optical, electronic, anti-corrosion, etc., properties, which make them attractive for a number of applications. In this article, we … Silicon oxycarbide coatings are the subject of research due to their exceptional optical, electronic, anti-corrosion, etc., properties, which make them attractive for a number of applications. In this article, we present a study on the synthesis and characterization of thin SiOC:H silicon oxycarbide films with the given composition and properties from a new organosilicon precursor octamethyl-1,4-dioxatetrasilacyclohexane (2D2) and its macromolecular equivalent-poly(oxybisdimethylsily1ene) (POBDMS). Layers from 2D2 precursor with different SiOC:H structure, from polymeric to ceramic-like, were produced in the remote microwave hydrogen plasma by CVD method (RHP-CVD) on a heated substrate in the temperature range of 30-400 °C. SiOC:H polymer layers from POEDMS were deposited from solution by spin coating and then crosslinked in RHP via the breaking of the Si-Si silyl bonds initiated by hydrogen radicals. The properties of SiOC:H layers obtained by both methods were compared. The density of the cross-linked materials was determined by the gravimetric method, elemental composition by means of XPS, chemical structure by FTIR spectroscopy, and NMR spectroscopy (13C, 29Si). Photoluminescence analyses and ellipsometric measurements were also performed. Surface morphology was characterized by AFM. Based on the obtained results, a mechanism of initiation, growth, and cross-linking of the CVD layers under the influence of hydrogen radicals was proposed.

Effect of MgO and Al2O3 precursors on 3D‐printed cordierite lattice structures by a novel emulsion‐based PDC route

2025-06-19

Valeria Diamanti , Hamada Elsayed , Tobias Fey +1 more | Journal of the American Ceramic Society

Abstract The development of advanced ceramic materials with tailored microstructures is essential for meeting the demands of many high‐performance applications. This study explores a novel polymer‐derived ceramic route for fabricating … Abstract The development of advanced ceramic materials with tailored microstructures is essential for meeting the demands of many high‐performance applications. This study explores a novel polymer‐derived ceramic route for fabricating porous cordierite lattice structures by using a silicone‐based emulsion as feedstock for direct ink writing. In this context, silicone blended with acrylates enabled the application of a hybrid technology, involving UV curing of the samples after 3D printing to stabilize shapes before high‐temperature ceramization. The ceramic product of the silicone‐based blend was engineered by emulsification of an aqueous phase, in turn suspending oxide nanoparticles and/or dissolving hydrated salts, acting as Al 2 O 3 and MgO precursors. Several combinations of Al 2 O 3 and MgO precursors were explored to highlight the versatility of the method in yielding cordierite ceramics. Finally, porous structures derived from the combination of hydrated salts were further characterized to investigate the morphology and microstructure of the produced samples, as well as the role of water in the formation of porous components.

Starch-driven fabrication of porous alumina membranes: Extrusion and consolidation casting methods

2025-06-19

Fariba Hamidivadigh , Mohsen Tohidnezhad , Hossein Sarpoolaky | Materials Chemistry and Physics

Recycling Si scrap for SiC-Y2O3-Al2O3 ceramics via a single-step process

2025-06-19

Sangha Shin , Jong-Wook Park , Min‐Soo Kim +3 more | Journal of Alloys and Compounds

Growth behavior and barrier mechanism of corrosion product layer from calcium-magnesium-aluminosilicate on Yb2Si2O7-Yb2SiO5 composite environmental barrier coatings at 1300 ℃

2025-06-18

Shuang Yu , Shuqi Wang , Yaming Wang +7 more | Corrosion Science

First-principles Study of Interstitial-Related Defects in Quartz

2025-06-18

Hiroyuki Kageshima , Toru Akiyama , Kenji Shiraishi | Journal of the Physical Society of Japan

Research on Shear Ablation and Thermal Insulation Performance of The Cf/SiBCN Polymer-Amorphous Ceramic Gradient Thermal Protection Composites

2025-06-18

Chunlei Xia , Weihua Xie , Songhe Meng +4 more | Journal of Alloys and Compounds

Interfacial Bonding Mechanism in HNBR Reinforced by In-situ Generated Organic-Inorganic Hybrid Network for Synergistic Mechanical Reinforcement

2025-06-18

Bin Zhu , Aifang Xue , Xiaokun XIAO +2 more | Polymer

Basic elements

2025-06-18

Cameron Gordon | Routledge eBooks

Fabrication and Properties of ITTO Segments for Cylindrical Targets by Pressureless Oxygen Atmosphere Sintering Method

2025-06-18

Jiwen Xu , Fangzhou Wu , Yuan Yao +3 more | Ceramics

Cylindrical targets have a high utilization rate, but are difficult to manufacture. A large hollow ITTO segment with thin walls was prepared by cold isostatic pressure and two-stage sintering. The … Cylindrical targets have a high utilization rate, but are difficult to manufacture. A large hollow ITTO segment with thin walls was prepared by cold isostatic pressure and two-stage sintering. The fabrication process yielded a segment with an outer diameter of 153 mm, an inner diameter of 135 mm, and a length of 700 mm, indicating a length to thickness ratio of up to 78. The dense and uniform green bodies ensure the achievement of high density and uniformity of the sintered body throughout its volume. The segment exhibited a high relative density of about 99.5% and a low resistivity of below 3.4 × 10−4 Ω·cm. The density and resistivity illustrate a minimal inhomogeneity along the length of the segment. The segment exhibits a cubic bixbyite phase and is characterized by densely packed fine grains with an average size of several microns. Therefore, these results establish a substantial foundation for the large-scale production of cylindrical ITTO segments.

Crystallographic and morphological characterization of high-crystalline α-alumina nanoparticles: A comprehensive X-ray diffraction and transmission electron microscopy study

2025-06-17

Raton Kumar Bishwas , Md. Ashraful Alam , Shirin Akter Jahan | Chemical Physics Letters

Development of Porous COP–Ceramic Composites for Application as Low-Relative- Permittivity, Low-Dielectric-Loss Substrates in Next-Generation Communication Systems

2025-06-17

Seisuke Ata , Takumi Ono , Yuto Kato | Research Square (Research Square)

<title>Abstract</title> The rapid advancements in communication technologies, such as the onset of 5G systems and the anticipated arrival of 6G systems, have increased the demand for materials with low relative … <title>Abstract</title> The rapid advancements in communication technologies, such as the onset of 5G systems and the anticipated arrival of 6G systems, have increased the demand for materials with low relative permittivity(<italic>e</italic>r) and dissipation factors(tanδ) to enable stable, low-power communication at higher frequencies. In this study, cycloolefin polymer (COP)-based composites comprising the fillers alumina (Al2O3) and aluminum nitride (AlN) were subjected to foaming by supercritical CO2 to introduce porosity, then evaluated as candidates for low-εr, low-tanδ substrates. Their dielectric properties were evaluated over a large frequency range of up to ~ 120 GHz using the balanced-type circular disk resonator method. Results demonstrated that porosity effectively reduced εr and tanδ without compromising the thermal properties; in particular, the COP–AlN composites exhibited εr and tanδ values below 2.0 and 1×10–3, respectively. Furthermore, the εr trends were consistent with effective medium theories, specifically the Maxwell–Garnett and Bruggeman models. Additional analyses of the thermal expansion and conductivities of the composites revealed enhanced compatibility with copper conductors, supporting the viability of these composites for next-generation communication devices.

Hot oscillatory pressing of highly transparent Y2O3 ceramics

2025-06-16

Linan An , Hongtian He , Hongyi Tian +3 more | Journal of the American Ceramic Society

Abstract In this work, the sintering behavior, microstructure, and transmittance of yttrium oxide (Y 2 O 3 ) ceramics prepared by hot pressing (HP) and hot oscillatory pressing (HOP) were … Abstract In this work, the sintering behavior, microstructure, and transmittance of yttrium oxide (Y 2 O 3 ) ceramics prepared by hot pressing (HP) and hot oscillatory pressing (HOP) were compared. The results revealed that compared to HP, HOP enhanced the sinterability of Y 2 O 3 by increasing the densification rate and final density of the material. Meanwhile, the oscillatory pressure used in HOP generated much more dislocations distributed along grain boundaries in the resultant sample compared to the constant pressure used in HP. The high dislocation density triggered recrystallization upon post‐annealing of the sample prepared by HOP, which leading to the significant reduction of residual stresses and dislocation density. As a result, the annealed HOP‐prepared sample exhibited much higher transmittance than the counterpart prepared by HP, particularly in the visible light range.

Synergistical Enhancement of the Processability, High‐Temperature Resistance, and Mechanical Properties of Silicone Resin Composite by Spherical Fillers

2025-06-16

Songyuan Tan , Ruolin Zhou , F. Xie +4 more | Polymer Composites

ABSTRACT This research explored the influence of silicone resin microspheres (SRMs) on the processing performance of silicone resin composites. In addition, the influence of hollow glass microspheres (HGMs) and precipitated … ABSTRACT This research explored the influence of silicone resin microspheres (SRMs) on the processing performance of silicone resin composites. In addition, the influence of hollow glass microspheres (HGMs) and precipitated silica on the high‐temperature resistance and mechanical properties of silicone resin composites was also studied. The results showed that SRMs expanded the processing window and enhanced processing performance of the composite. After adding SRMs, the spiral flow of the composite became more stable. The composite with 40 phr of SRMs had good fluidity between 120°C and 160°C, remaining consistent even with varied compression—molding times. The optimal SRM40‐HGM5 formulation significantly improved the lightweight, high‐temperature resistance, and mechanical properties of the silicone resin composites. Compared with SRM0, SRM40‐HGM5 exhibited reduced density by 20%, increased bending and impact strengths by 136% and 134%, respectively, and raised T 10% from 691°C to 791°C. After 100‐h thermal aging at 300°C, SRM40‐HGM5 retained as high as 87.35% of impact strength and 96.4% of bending strength. This study provides guidance for the development of high‐performance silicone resin composite materials in extreme environments.

Oxidation resistance and strength retention behavior of fibrous monolithic ZrB2-SiC ceramic

2025-06-16

Qingyun Han , Chuncheng Wei , Longfei Wang +4 more | Journal of Materials Science

Effect of K2O/Na2O addition on the microstructure and mechanical properties of CaO‐MgO‐Al2O3‐SiO2 glass ceramic

2025-06-16

Hong‐Yang Wang , Shuqiang Jiao , Guo‐Hua Zhang | International Journal of Applied Ceramic Technology

Abstract This work studied the effects of types of flux (K 2 O and Na 2 O) and sintering temperature on the microstructure and mechanical properties of augite‐based glass ceramics … Abstract This work studied the effects of types of flux (K 2 O and Na 2 O) and sintering temperature on the microstructure and mechanical properties of augite‐based glass ceramics (GCs). Fine glass powder ( D 50 = 1.07 µm) was used as the starting material for preparing the GCs. The porosity of the samples decreased by increasing the sintering temperature from 850°C to 925°C, and a further increase in the sintering temperature to 950°C caused an increase in porosity from 0.2 to 1.8 vol%. The substitution of K 2 O for Na 2 O reduced the densification degree of GC. Nevertheless, K 2 O refined the grain size of augite to 24–33 nm, which enhanced the hardness of GC. Both Na 2 O‐containing and K 2 O‐containing GC prepared at 925°C showed their highest bending strength (GC‐Na: 225 MPa, GC‐K: 215 MPa) and Vickers hardness (GC‐Na: 8.39 GPa, GC‐K: 8.41 GPa).

Development of a reaction bonding method for bonding silicon carbide using ceramic suspensions

2025-06-15

Rodrigo Orta‐Guerra , Olivia Brandt , Averyonna Kimery +3 more | International Journal of Applied Ceramic Technology

Abstract Bonding ceramic‐based components is desired to create more complex assemblies. In this work, a method for bonding sintered SiC components via reaction bonding based on SiC/carbon black (CB) ceramic … Abstract Bonding ceramic‐based components is desired to create more complex assemblies. In this work, a method for bonding sintered SiC components via reaction bonding based on SiC/carbon black (CB) ceramic suspensions was developed. Four‐point flexural testing was used to evaluate the strength of the bond. The effect of bond thickness and temperature on strength was evaluated. The SiC/CB 37 vol% suspension, with a polyethyleneimine content of 1.7 wt% and a pH between 5 and 7, displayed suitable rheology for slurry casting on SiC. At room temperature, a bond thickness of 100 ± 6 µm displayed the highest flexural strength (242 ± 35 MPa). Ten specimens with a 60 ± 4 µm bond thickness were tested at room temperature and 1200°C, with strengths of 229 ± 50 MPa and 278 ± 45 MPa measured, respectively. The presence of SiC in the bond area was verified and quantified with X‐ray diffraction, energy‐dispersive X‐ray spectroscopy, and image analysis.

Effect of Sintering Temperature on Mechanical Properties of the Mullite/ZTA Composites

2025-06-12

Mohammed Abosobh Elshaer , Ahmed A. Amer , Menna A. Saleh +3 more | Bulletin of Faculty of Science Zagazig University

Iron element behavior and microstructure evolution of mullite–corundum ceramics in high‐temperature CO atmosphere

2025-06-12

Hongxing Zhan , Hailu Wang , Yuanbing Li +3 more | Journal of the American Ceramic Society

Abstract This study focuses on the corrosion behavior of Al 2 O 3 –SiO 2 refractory materials under high‐temperature CO atmospheres in hydrogen metallurgy, systematically revealing the occurrence form of … Abstract This study focuses on the corrosion behavior of Al 2 O 3 –SiO 2 refractory materials under high‐temperature CO atmospheres in hydrogen metallurgy, systematically revealing the occurrence form of Fe element in mullite–corundum ceramics with different Fe 2 O 3 contents. By simulating hydrogen metallurgy conditions and integrating thermodynamic analysis, phase evolution, and microstructural characterization, a dual intragranular and grain boundary corrosion mechanism was identified: (1) Fe 3+ in the [Al/FeO 6 ] octahedron of the mullite crystals were reduced to Fe 2+ and leached out of the lattice, resulting in charge imbalance and lattice distortion within the structure, thus reducing the stability of the mullite crystal. (2) Migrated Fe and impurities element at grain boundaries promote glass phase precipitation, while leached Fe 2+ reduces glass viscosity by disrupting Si–O networks, forming low‐viscosity liquids that accelerate mullite dissolution. Results demonstrate a critical Fe 2 O 3 doping threshold (10 wt%), beyond which mullite undergoes reductive dissociation accompanied by hercynite and low‐melting phase formation (ferrocordierite, fayalite). Hercynite and glass phase contents exhibit near‐linear increases with Fe content. This work clarifies the valence of the Fe element and its gradient‐driven microstructural failure mechanisms under hydrogen metallurgy conditions, providing theoretical foundations for optimizing reduction‐resistant mullite‐based linings.

Response behavior and optimization strategy of UHTC–SiC dual‐layer coatings under high heat flux ablation environments

2025-06-12

Xiaoxuan Li , Songlin Chen , Chenglong Tan +3 more | Journal of the American Ceramic Society

Abstract With more stringent requirements on assessment temperatures and ablation time, traditional ultrahigh temperature ceramic (UHTC)–SiC dual‐layer coating design for C/C composites is at risk of structural failure and reduced … Abstract With more stringent requirements on assessment temperatures and ablation time, traditional ultrahigh temperature ceramic (UHTC)–SiC dual‐layer coating design for C/C composites is at risk of structural failure and reduced service reliability. Herein, as‐designed C/C composites with [HfC/ZrC/HfC]–SiC dual‐layer coatings were tested under three different ablation temperatures (2300°C, 2600°C, 2700°C). The increase in temperature resulted in a significant change in linear ablation rates, ranging from −0.17 µm/s (2300°C) to −34.15 µm/s (2700°C). Based on experiments and finite element analysis (FEA), the primary coating failure mechanism, when the ablation temperature was raised to 2700°C, was attributed to high temperature on the SiC transition layer (>2230°C), leading to rapid escape of gaseous SiO and CO from SiC active oxidation. A new, integrated design that forms a ZrC–SiC transition layer (between UHTC layer and C/C composites) demonstrated the ability to resist high heat flux oxyacetylene flame with low ablation rate (−1.70 µm/s, 90 s) and maintained sufficient interface stability at an assessment temperature of ∼2700°C. This work provides new insights and might help guide design of future antioxidation coatings and their assessment methods.

The Influence of Heat Treatment Temperature on the Oxidation Resistance of Aluminium Waste Slurry Coating

2025-06-12

Nurul Latifah , Arif Tjahjono , Eni Sugiarti +6 more | Journal of Materials Engineering and Performance