Weiping Gong, Duoduo Zhang, Lang Xiao, Jiahui Zhao, Ting Wang, Kai Li, Zhentin Zhao, Manuel Scharrer, Alexandra Navrotsky
The Aurivillius compounds in the Bi2O3–Fe2O3–TiO2 system, combining ferroelectric, semiconducting, and ferromagnetic properties, have attracted particular interest. Formation kinetics and thermodynamic stability are the fundamental knowledge needed for modeling and predicting the temporal microstructure and property evolution during materials processing but have not yet been addressed by quantitative experimental measurement. This article focuses on the Bin+1Fen–3Ti3O3n+3 Aurivillius compounds on the Bi4Ti3O12–BiFeO3 tie‐line to elucidate the mechanisms and thermodynamic controls responsible for phase formation of compounds with various perovskite‐like layers. Five high‐purity Aurivillius compounds Bi4Ti3O12, Bi5FeTi3O15, Bi6Fe2Ti3O18, Bi7Fe3Ti3O21, and Bi8Fe4Ti3O24 with integer n = 3–7 values were synthesized and their phase transformation properties and enthalpies of formation were studied by X‐ray diffraction in situ, high temperature differential scanning calorimetry, and high temperature oxide melt solution calorimetry. Thermodynamic stability of the compounds decreases with increasing n, and formation kinetics gradually slow down, demonstrating the inherent difficulty to synthesize pure Aurivillius compounds with n larger than 8. This difficulty was confirmed by an impurity phase coexisting with Bi9Fe5Ti3O27.
Bi2O3-Fe2O3-TiO2 系统中的 Aurivillius 化合物集铁电、半导体和铁磁特性于一身，引起了人们的特别关注。形成动力学和热力学稳定性是建模和预测材料加工过程中微观结构和性能演变的基本知识，但尚未通过定量实验测量来解决这一问题。本文以 Bi4Ti3O12-BiFeO3 连接线上的 Bin+1Fen-3Ti3O3n+3 Aurivillius 化合物为研究对象，阐明了具有各种类包晶层的化合物相形成的机理和热力学控制。合成了五种高纯度奥里维利乌斯化合物 Bi4Ti3O12、Bi5FeTi3O15、Bi6Fe2Ti3O18、Bi7Fe3Ti3O21 和 Bi8Fe4Ti3O24（n=3-7），并通过 X 射线原位衍射、高温差示扫描量热法和高温氧化物熔解量热法研究了它们的相变性质和形成焓。这些化合物的热力学稳定性随着 n 的增大而降低，形成动力学也逐渐减慢，这表明很难合成出 n 大于 8 的纯 Aurivillius 化合物。
{"title":"Formation kinetics and thermodynamic stability of the Aurivillius compounds in Bi4Ti3O12–BiFeO3 system","authors":"Weiping Gong, Duoduo Zhang, Lang Xiao, Jiahui Zhao, Ting Wang, Kai Li, Zhentin Zhao, Manuel Scharrer, Alexandra Navrotsky","doi":"10.1111/jace.19970","DOIUrl":"https://doi.org/10.1111/jace.19970","url":null,"abstract":"The Aurivillius compounds in the Bi<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>–Fe<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>–TiO<jats:sub>2</jats:sub> system, combining ferroelectric, semiconducting, and ferromagnetic properties, have attracted particular interest. Formation kinetics and thermodynamic stability are the fundamental knowledge needed for modeling and predicting the temporal microstructure and property evolution during materials processing but have not yet been addressed by quantitative experimental measurement. This article focuses on the Bi<jats:italic><jats:sub>n</jats:sub></jats:italic><jats:sub>+1</jats:sub>Fe<jats:italic><jats:sub>n</jats:sub></jats:italic><jats:sub>–3</jats:sub>Ti<jats:sub>3</jats:sub>O<jats:sub>3</jats:sub><jats:italic><jats:sub>n</jats:sub></jats:italic><jats:sub>+3</jats:sub> Aurivillius compounds on the Bi<jats:sub>4</jats:sub>Ti<jats:sub>3</jats:sub>O<jats:sub>12</jats:sub>–BiFeO<jats:sub>3</jats:sub> tie‐line to elucidate the mechanisms and thermodynamic controls responsible for phase formation of compounds with various perovskite‐like layers. Five high‐purity Aurivillius compounds Bi<jats:sub>4</jats:sub>Ti<jats:sub>3</jats:sub>O<jats:sub>12</jats:sub>, Bi<jats:sub>5</jats:sub>FeTi<jats:sub>3</jats:sub>O<jats:sub>15</jats:sub>, Bi<jats:sub>6</jats:sub>Fe<jats:sub>2</jats:sub>Ti<jats:sub>3</jats:sub>O<jats:sub>18</jats:sub>, Bi<jats:sub>7</jats:sub>Fe<jats:sub>3</jats:sub>Ti<jats:sub>3</jats:sub>O<jats:sub>21</jats:sub>, and Bi<jats:sub>8</jats:sub>Fe<jats:sub>4</jats:sub>Ti<jats:sub>3</jats:sub>O<jats:sub>24</jats:sub> with integer <jats:italic>n </jats:italic>= 3–7 values were synthesized and their phase transformation properties and enthalpies of formation were studied by X‐ray diffraction in situ, high temperature differential scanning calorimetry, and high temperature oxide melt solution calorimetry. Thermodynamic stability of the compounds decreases with increasing <jats:italic>n</jats:italic>, and formation kinetics gradually slow down, demonstrating the inherent difficulty to synthesize pure Aurivillius compounds with <jats:italic>n</jats:italic> larger than 8. This difficulty was confirmed by an impurity phase coexisting with Bi<jats:sub>9</jats:sub>Fe<jats:sub>5</jats:sub>Ti<jats:sub>3</jats:sub>O<jats:sub>27</jats:sub>.","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141517722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ZrN–SiO2 core–shell particles were prepared, where the ZrN core nanoparticles and SiO2 shell were designed to exhibit localized surface plasmon resonances (LSPRs) and structural coloring. The heating of ZrO2 nanoparticles with Mg3N2 under a nitrogen gas flow produced ZrN nanoparticles with a diameter in the range of 10–20 nm. The dispersion of ZrN nanoparticles in water exhibited an absorption maximum at approximately 700 nm owing to LSPRs. An SiO2 shell was formed on the ZrN nanoparticles using a sol–gel process. Scanning transmission electron microscopy confirmed the formation of ZrN–SiO2 core–shell particles containing ZrN particles with a diameter of approximately 10 nm. The SiO2 shell thickness was controlled by varying the reaction time to form SiO2. The use of particles as a structural component of a structural color material owing to the high uniformity of the size of obtained core–shell particles was investigated. The obtained ZrN–SiO2 core–shell particles were arrayed on a glass substrate using a layer‐by‐layer method. The particle‐stacked film of the ZrN–SiO2 core–shell particles exhibited the maximum reflection depending on the particle size of the SiO2 shell.
{"title":"Synthesis of ZrN–SiO2 core–shell particles by a sol–gel process and use as particle‐based structured coloring material","authors":"Shinji Noguchi, Akira Miura, Kiyoharu Tadanaga","doi":"10.1111/jace.19981","DOIUrl":"https://doi.org/10.1111/jace.19981","url":null,"abstract":"ZrN–SiO<jats:sub>2</jats:sub> core–shell particles were prepared, where the ZrN core nanoparticles and SiO<jats:sub>2</jats:sub> shell were designed to exhibit localized surface plasmon resonances (LSPRs) and structural coloring. The heating of ZrO<jats:sub>2</jats:sub> nanoparticles with Mg<jats:sub>3</jats:sub>N<jats:sub>2</jats:sub> under a nitrogen gas flow produced ZrN nanoparticles with a diameter in the range of 10–20 nm. The dispersion of ZrN nanoparticles in water exhibited an absorption maximum at approximately 700 nm owing to LSPRs. An SiO<jats:sub>2</jats:sub> shell was formed on the ZrN nanoparticles using a sol–gel process. Scanning transmission electron microscopy confirmed the formation of ZrN–SiO<jats:sub>2</jats:sub> core–shell particles containing ZrN particles with a diameter of approximately 10 nm. The SiO<jats:sub>2</jats:sub> shell thickness was controlled by varying the reaction time to form SiO<jats:sub>2</jats:sub>. The use of particles as a structural component of a structural color material owing to the high uniformity of the size of obtained core–shell particles was investigated. The obtained ZrN–SiO<jats:sub>2</jats:sub> core–shell particles were arrayed on a glass substrate using a layer‐by‐layer method. The particle‐stacked film of the ZrN–SiO<jats:sub>2</jats:sub> core–shell particles exhibited the maximum reflection depending on the particle size of the SiO<jats:sub>2</jats:sub> shell.","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141531182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kyeonggon Choi, Seung‐Wook Kim, Jae‐Hyoung Lee, Baojin Chu, Dae‐Yong Jeong
Glass is one of the most essential materials in various industrial fields. A representative application is as interposers in the semiconductor and display industries and microfluidic devices in the bio‐industry. Due to technological advancements, electric devices and various products are becoming lighter and smaller. Consequently, precision processing of the substrate is becoming increasingly important. One significant leading technology among these is through glass via (TGV) technology, which is attracting attention as a future alternative to through silicon via. In particular, TGV should be capable of microfabrication with a large aspect ratio and a consistent small hole size. TGV is typically fabricated using a wet etching process, so wet etching technology is a prominent focus in microfabrication. However, glass has isotropic properties, making achieving a high aspect ratio difficult. Traditionally, research on the wet etching method using hydrofluoric acid (HF) has been conducted. Nevertheless, HF etching has several disadvantages, including air pollution and human harm. Additional studies have been performed to address these issues. This review paper will cover the conventional HF‐based wet etching method and alternative HF etching processes (eco‐friendly materials). This technology would significantly help overcome the traditional problems associated with HF etching and fabricating precision‐processed glass in the semiconductor, display, and bio‐device industries.
{"title":"Eco‐friendly glass wet etching for MEMS application: A review","authors":"Kyeonggon Choi, Seung‐Wook Kim, Jae‐Hyoung Lee, Baojin Chu, Dae‐Yong Jeong","doi":"10.1111/jace.19961","DOIUrl":"https://doi.org/10.1111/jace.19961","url":null,"abstract":"Glass is one of the most essential materials in various industrial fields. A representative application is as interposers in the semiconductor and display industries and microfluidic devices in the bio‐industry. Due to technological advancements, electric devices and various products are becoming lighter and smaller. Consequently, precision processing of the substrate is becoming increasingly important. One significant leading technology among these is through glass via (TGV) technology, which is attracting attention as a future alternative to through silicon via. In particular, TGV should be capable of microfabrication with a large aspect ratio and a consistent small hole size. TGV is typically fabricated using a wet etching process, so wet etching technology is a prominent focus in microfabrication. However, glass has isotropic properties, making achieving a high aspect ratio difficult. Traditionally, research on the wet etching method using hydrofluoric acid (HF) has been conducted. Nevertheless, HF etching has several disadvantages, including air pollution and human harm. Additional studies have been performed to address these issues. This review paper will cover the conventional HF‐based wet etching method and alternative HF etching processes (eco‐friendly materials). This technology would significantly help overcome the traditional problems associated with HF etching and fabricating precision‐processed glass in the semiconductor, display, and bio‐device industries.","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141517720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The oxidation resistance of yttria‐stabilized zirconia (YSZ) thermal barrier coatings and conductivity of YSZ solid oxide fuel cells are closely related to the diffusion of oxygen ions () in YSZ, but the diffusion behavior in small‐sized YSZ samples under non‐isothermal condition where the temperature gradient () could be significant remaining elusive. Herein, we disclose the previously unrevealed effect of extreme on the self‐diffusion behavior of in both pristine and strained YSZ. It is found that the self‐diffusion coefficient () experiences a nearly one‐fold increase under an extreme around 60 K/Å. The diffusion direction tends to be toward regions of high temperature. Uniaxial stress is revealed to reduce due to the increased activation energy of ions, whereas promotes the self‐diffusion in the stressed system. These results underscore the role of in influencing the self‐diffusion behavior of YSZ, providing a theoretical guideline for examining ceramics serving in extreme environments.
{"title":"Extreme temperature gradient promoting oxygen diffusion in yttria‐stabilized zirconia: A molecular dynamics study","authors":"Jian Guo, Yan Yin, Min Yi","doi":"10.1111/jace.19996","DOIUrl":"https://doi.org/10.1111/jace.19996","url":null,"abstract":"The oxidation resistance of yttria‐stabilized zirconia (YSZ) thermal barrier coatings and conductivity of YSZ solid oxide fuel cells are closely related to the diffusion of oxygen ions () in YSZ, but the diffusion behavior in small‐sized YSZ samples under non‐isothermal condition where the temperature gradient () could be significant remaining elusive. Herein, we disclose the previously unrevealed effect of extreme on the self‐diffusion behavior of in both pristine and strained YSZ. It is found that the self‐diffusion coefficient () experiences a nearly one‐fold increase under an extreme around 60 K/Å. The diffusion direction tends to be toward regions of high temperature. Uniaxial stress is revealed to reduce due to the increased activation energy of ions, whereas promotes the self‐diffusion in the stressed system. These results underscore the role of in influencing the self‐diffusion behavior of YSZ, providing a theoretical guideline for examining ceramics serving in extreme environments.","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141506241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We report novel oxide glasses that are compatible with ultra-high Young's modulus (∼150 GPa) and a small coefficient of thermal expansion (∼5.0 ppm/K). These glasses were prepared using a conventional melt-quenching technique. The viscosity–temperature relation provides the reshaping temperature for the stiff and less dilated oxide glasses. The origin of the ultra-high Young's modulus is the inclusion of Y2O3 as well as five- and six-coordinated alumina oxide and Ta2O5, which has a large ionic packing ratio due to higher oxygen coordination numbers. On the other hand, the small thermal expansion coefficient originates from including Ta2O5 and SiO2 with large dissociation energy due to strong bonds.
{"title":"Yttria substitution effect of tantalate aluminosilicate glasses with ultra-high Young's modulus","authors":"Katsuki Hayashi, Hikaru Nishizaki, Kazuki Mitsui, Grégory Tricot, Akira Saitoh","doi":"10.1111/jace.19995","DOIUrl":"https://doi.org/10.1111/jace.19995","url":null,"abstract":"We report novel oxide glasses that are compatible with ultra-high Young's modulus (∼150 GPa) and a small coefficient of thermal expansion (∼5.0 ppm/K). These glasses were prepared using a conventional melt-quenching technique. The viscosity–temperature relation provides the reshaping temperature for the stiff and less dilated oxide glasses. The origin of the ultra-high Young's modulus is the inclusion of Y<sub>2</sub>O<sub>3</sub> as well as five- and six-coordinated alumina oxide and Ta<sub>2</sub>O<sub>5</sub>, which has a large ionic packing ratio due to higher oxygen coordination numbers. On the other hand, the small thermal expansion coefficient originates from including Ta<sub>2</sub>O<sub>5</sub> and SiO<sub>2</sub> with large dissociation energy due to strong bonds.","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141517721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Huihui Yan, Kun Wang, Liping Zhao, Peng Zhang, Han Chen, Jing Liu, Lian Gao
A new type of Ni/Al2O3 self‐supporting catalysts, with high specific surface area, was fabricated by blow‐spinning technology. These Ni/Al2O3 self‐supporting catalysts are hollow flexible fibers and were utilized for the dry reforming of methane. The Ni/Al2O3 catalysts exhibited exceptional catalytic performance, maintaining their activity for over 150‐h at a high temperature of 800°C. The Ni nanoparticles disputed on the hollow fibers demonstrated remarkable resistance to sintering and coking during high‐temperature catalysis. This was a noteworthy feature, as sintering and coking are common challenges faced by catalysts during high‐temperature reactions. Furthermore, the catalysts retained its activity even after a rigorous 150‐h test at 800°C, indicating its durability and stability. Importantly, the Ni/Al2O3 self‐supporting could be successfully reactivated after the test, further highlighting its reusable nature. This study offers promising new avenues for the development of high‐temperature, self‐supporting, and reactivatable catalysts.
{"title":"Flexible hollow Ni/Al2O3 fibers: A sustainable and reusable catalyst for efficient dry reforming of methane","authors":"Huihui Yan, Kun Wang, Liping Zhao, Peng Zhang, Han Chen, Jing Liu, Lian Gao","doi":"10.1111/jace.19990","DOIUrl":"https://doi.org/10.1111/jace.19990","url":null,"abstract":"A new type of Ni/Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> self‐supporting catalysts, with high specific surface area, was fabricated by blow‐spinning technology. These Ni/Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> self‐supporting catalysts are hollow flexible fibers and were utilized for the dry reforming of methane. The Ni/Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> catalysts exhibited exceptional catalytic performance, maintaining their activity for over 150‐h at a high temperature of 800°C. The Ni nanoparticles disputed on the hollow fibers demonstrated remarkable resistance to sintering and coking during high‐temperature catalysis. This was a noteworthy feature, as sintering and coking are common challenges faced by catalysts during high‐temperature reactions. Furthermore, the catalysts retained its activity even after a rigorous 150‐h test at 800°C, indicating its durability and stability. Importantly, the Ni/Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> self‐supporting could be successfully reactivated after the test, further highlighting its reusable nature. This study offers promising new avenues for the development of high‐temperature, self‐supporting, and reactivatable catalysts.","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141517723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Functionally multilayered environmental barrier coatings (EBCs) with the desired layer sequence of Yb2O3/Yb2SiO5/Yb2Si2O7/SiO2/Si were obtained using an unconventional yet simple technique of reactive sintering. Yb2O3 slurry was sprayed on polycrystalline silicon (used as a bond coat for SiCf/SiC composites) and reactive sintered to generate graded layers that provide a combination of mitigated thermal expansion mismatch as well as silica activity. The Yb2O3‐terpineol slurry produced a uniform deposit of the Yb2O3 topcoat. Reactive sintering of exploratory coatings (t ∼ 10–20 µm) was carried out in air by varying the temperature (1100–1400°C) and time (2–24 h). X‐ray diffraction and scanning electron microscopy‐energy‐dispersive spectroscopy technique confirmed the in situ formation of X2‐Yb2SiO5 and β‐Yb2Si2O7. Rietveld refinement was performed to know the volume fractions of the respective phases. The set of process parameters identified from the preliminary work was employed to fabricate EBCs with thickness ∼ 250 µm. The X2‐Yb2SiO5 and β‐Yb2Si2O7 phases formed next to the Si/SiO2 interface as two separate layers. Post‐sintering heat treatments in air at 1300, 1350, and 1400°C for 3–50 h elucidated the growth characteristics of the oxide layers to be a function of both temperature and time. The theoretical considerations of diffusional reactive phase formation of the EBC multilayer growth rates are discussed.
{"title":"Functionally multilayered Yb‐silicate EBCs fabricated using slurry spraying‐reactive sintering technique","authors":"Gauri Waghmare, Vikram Hastak, Ashutosh S. Gandhi","doi":"10.1111/jace.19983","DOIUrl":"https://doi.org/10.1111/jace.19983","url":null,"abstract":"Functionally multilayered environmental barrier coatings (EBCs) with the desired layer sequence of Yb<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>/Yb<jats:sub>2</jats:sub>SiO<jats:sub>5</jats:sub>/Yb<jats:sub>2</jats:sub>Si<jats:sub>2</jats:sub>O<jats:sub>7</jats:sub>/SiO<jats:sub>2</jats:sub>/Si were obtained using an unconventional yet simple technique of reactive sintering. Yb<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> slurry was sprayed on polycrystalline silicon (used as a bond coat for SiC<jats:sub>f</jats:sub>/SiC composites) and reactive sintered to generate graded layers that provide a combination of mitigated thermal expansion mismatch as well as silica activity. The Yb<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>‐terpineol slurry produced a uniform deposit of the Yb<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> topcoat. Reactive sintering of exploratory coatings (<jats:italic>t </jats:italic>∼ 10–20 µm) was carried out in air by varying the temperature (1100–1400°C) and time (2–24 h). X‐ray diffraction and scanning electron microscopy‐energy‐dispersive spectroscopy technique confirmed the in situ formation of X<jats:sub>2</jats:sub>‐Yb<jats:sub>2</jats:sub>SiO<jats:sub>5</jats:sub> and β‐Yb<jats:sub>2</jats:sub>Si<jats:sub>2</jats:sub>O<jats:sub>7</jats:sub>. Rietveld refinement was performed to know the volume fractions of the respective phases. The set of process parameters identified from the preliminary work was employed to fabricate EBCs with thickness ∼ 250 µm. The X<jats:sub>2</jats:sub>‐Yb<jats:sub>2</jats:sub>SiO<jats:sub>5</jats:sub> and β‐Yb<jats:sub>2</jats:sub>Si<jats:sub>2</jats:sub>O<jats:sub>7</jats:sub> phases formed next to the Si/SiO<jats:sub>2</jats:sub> interface as two separate layers. Post‐sintering heat treatments in air at 1300, 1350, and 1400°C for 3–50 h elucidated the growth characteristics of the oxide layers to be a function of both temperature and time. The theoretical considerations of diffusional reactive phase formation of the EBC multilayer growth rates are discussed.","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141517724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
If the temperature and environment effects on the oxidation of SiC fibers have been extensively documented, the impact of external stresses (stress‐oxidation coupling effect) remains questioned. Therefore, interrupted static fatigue tests were conducted on filaments. Surviving specimens (>60%) were subsequently tensile tested and fracture surfaces recovered for analysis. The external stress was found to have no impact on the oxidation regime (linear or parabolic) nor on its rate, which is comparable to literature data. As long as the slow crack growth (SCG) incubates (negligible growth rate), the oxidation was shown to govern the embrittlement. Fracture surface analysis revealed tensile residual stresses, attributed to a wedge effect when specimens were unloaded. Rare tests (<2%) were interrupted while the crack had significantly grown highlighting the successive crack fronts. Sources of residual stresses and differences between fiber types (flaw position inducing a bias on lifetime prediction) are discussed. In these circumstances, a coupling effect between the oxidation embrittlement and the SCG could be assumed for moderate stress levels, which is pertinent for most of ceramic matrix composite applications.
{"title":"Oxidation under stress of SiC‐based fibers at intermediate temperature and ambient air","authors":"S. Mazerat, J. El‐Morsli, R. Sarrazin, R. Pailler","doi":"10.1111/jace.19979","DOIUrl":"https://doi.org/10.1111/jace.19979","url":null,"abstract":"If the temperature and environment effects on the oxidation of SiC fibers have been extensively documented, the impact of external stresses (stress‐oxidation coupling effect) remains questioned. Therefore, interrupted static fatigue tests were conducted on filaments. Surviving specimens (>60%) were subsequently tensile tested and fracture surfaces recovered for analysis. The external stress was found to have no impact on the oxidation regime (linear or parabolic) nor on its rate, which is comparable to literature data. As long as the slow crack growth (SCG) incubates (negligible growth rate), the oxidation was shown to govern the embrittlement. Fracture surface analysis revealed tensile residual stresses, attributed to a wedge effect when specimens were unloaded. Rare tests (<2%) were interrupted while the crack had significantly grown highlighting the successive crack fronts. Sources of residual stresses and differences between fiber types (flaw position inducing a bias on lifetime prediction) are discussed. In these circumstances, a coupling effect between the oxidation embrittlement and the SCG could be assumed for moderate stress levels, which is pertinent for most of ceramic matrix composite applications.","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141506243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Johanna C. Sänger, Birte Riechers, Brian R. Pauw, Robert Maaß, Jens Günster
Two‐photon polymerization (2PP) additive manufacturing (AM) utilizes feedstocks of ceramic nanoparticles of a few nanometers in diameter, enabling the fabrication of highly accurate technical ceramic design with structural details as small as 500 nm. The performance of these materials is expected to differ from conventional AM ceramics, as nanoparticles and three‐dimensional printing at high resolution introduce new microstructural aspects. This study applies 2PP‐AM of yttria‐stabilized zirconia to investigate the mechanical response behavior under compressive load, probing the influence of smallest structural units induced by the line packing during the printing process, design of sintered microblocks, and sintering temperature and thereby microstructure. We find a dissipative mechanical response enhanced by sintering at lower temperatures than conventional. The pursued 2PP‐AM approach yields a microstructured material with an increased number of grain boundaries that proposedly play a major role in facilitating energy dissipation within the here printed ceramic material. This microplastic response is further triggered by the filigree structures induced by hollow line packing at the order of the critical defect size of ceramics. Together, these unique aspects made accessible by the 2PP‐AM approach contribute to a heterogeneous nano‐ and microstructure, and hint toward opportunities for tailoring the mechanical response in future ceramic applications.
双光子聚合（2PP）增材制造（AM）利用直径仅为几纳米的陶瓷纳米颗粒作为原料，能够制造出结构细节小至 500 纳米的高精度技术陶瓷设计。由于纳米颗粒和高分辨率三维打印带来了新的微观结构，这些材料的性能预计将有别于传统的 AM 陶瓷。本研究应用钇稳定氧化锆的 2PP-AM 技术研究了压缩载荷下的机械响应行为，探究了打印过程中线包装引起的最小结构单元的影响、烧结微块的设计、烧结温度以及由此产生的微观结构。我们发现，在比传统温度更低的温度下烧结可增强耗散机械响应。所采用的 2PP-AM 方法产生的微结构材料具有更多的晶界，这些晶界在促进印刷陶瓷材料的能量耗散方面发挥了重要作用。在陶瓷临界缺陷尺寸的数量级上，空心线填料诱发的丝状结构进一步触发了这种微塑性反应。总之，2PP-AM 方法的这些独特之处有助于形成异质纳米和微观结构，并为在未来的陶瓷应用中定制机械响应提供了机会。
{"title":"Microplastic response of 2PP‐printed ceramics","authors":"Johanna C. Sänger, Birte Riechers, Brian R. Pauw, Robert Maaß, Jens Günster","doi":"10.1111/jace.19849","DOIUrl":"https://doi.org/10.1111/jace.19849","url":null,"abstract":"Two‐photon polymerization (2PP) additive manufacturing (AM) utilizes feedstocks of ceramic nanoparticles of a few nanometers in diameter, enabling the fabrication of highly accurate technical ceramic design with structural details as small as 500 nm. The performance of these materials is expected to differ from conventional AM ceramics, as nanoparticles and three‐dimensional printing at high resolution introduce new microstructural aspects. This study applies 2PP‐AM of yttria‐stabilized zirconia to investigate the mechanical response behavior under compressive load, probing the influence of smallest structural units induced by the line packing during the printing process, design of sintered microblocks, and sintering temperature and thereby microstructure. We find a dissipative mechanical response enhanced by sintering at lower temperatures than conventional. The pursued 2PP‐AM approach yields a microstructured material with an increased number of grain boundaries that proposedly play a major role in facilitating energy dissipation within the here printed ceramic material. This microplastic response is further triggered by the filigree structures induced by hollow line packing at the order of the critical defect size of ceramics. Together, these unique aspects made accessible by the 2PP‐AM approach contribute to a heterogeneous nano‐ and microstructure, and hint toward opportunities for tailoring the mechanical response in future ceramic applications.","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141517725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A novel Cu35Ni35Cr10Fe10Sn10 high‐entropy alloy (HEA) filler with a relatively low melting point (935°C) was designed for brazing diamonds, and its technical advantages over conventional NiCr‐based fillers, that is, favorable wettability, high bonding strength, low thermal damage, and high mechanical performance, were convincingly demonstrated. The newly developed HEA filler had a contact angle of only 11° on the graphite (energetically close to diamond) surface and it could braze diamonds at 1000°C, much lower than the brazing temperature of conventional NiCr‐based fillers. Consequently, the brazed diamond exhibited greatly decreased surface thermal damage, higher fracture strength, and better wear performance. The solidified microstructure of the HEA filler contained three solid solution phases, that is, FeCrNi‐rich, CuNi‐rich, and CuSnNi‐rich phases that were formed through the liquid phase separation process, plus a minor phase of nanosized FeCr‐rich precipitates. The reaction products at the HEA filler/diamond interface were simply an inner Cr3C2 layer and an outer Cr7C3 layer, without other complex brittle compounds that are commonly seen in NiCr‐based fillers after diamond brazing. Apparently, the HEA filler reacted more sufficiently with diamonds, which contributed to improve the bonding strength and wear resistance of the brazed diamond. This work provided a new application scenario for HEAs as promising filler materials for brazing diamonds.
{"title":"Diamonds brazing with a novel Cu35Ni35Cr10Fe10Sn10 high‐entropy alloy filler","authors":"Haifeng Wei, Hui Zhang, Dong Xu, Weihuo Li, Qiang Hu, Sheng Guo","doi":"10.1111/jace.19984","DOIUrl":"https://doi.org/10.1111/jace.19984","url":null,"abstract":"A novel Cu<jats:sub>35</jats:sub>Ni<jats:sub>35</jats:sub>Cr<jats:sub>10</jats:sub>Fe<jats:sub>10</jats:sub>Sn<jats:sub>10</jats:sub> high‐entropy alloy (HEA) filler with a relatively low melting point (935°C) was designed for brazing diamonds, and its technical advantages over conventional NiCr‐based fillers, that is, favorable wettability, high bonding strength, low thermal damage, and high mechanical performance, were convincingly demonstrated. The newly developed HEA filler had a contact angle of only 11° on the graphite (energetically close to diamond) surface and it could braze diamonds at 1000°C, much lower than the brazing temperature of conventional NiCr‐based fillers. Consequently, the brazed diamond exhibited greatly decreased surface thermal damage, higher fracture strength, and better wear performance. The solidified microstructure of the HEA filler contained three solid solution phases, that is, FeCrNi‐rich, CuNi‐rich, and CuSnNi‐rich phases that were formed through the liquid phase separation process, plus a minor phase of nanosized FeCr‐rich precipitates. The reaction products at the HEA filler/diamond interface were simply an inner Cr<jats:sub>3</jats:sub>C<jats:sub>2</jats:sub> layer and an outer Cr<jats:sub>7</jats:sub>C<jats:sub>3</jats:sub> layer, without other complex brittle compounds that are commonly seen in NiCr‐based fillers after diamond brazing. Apparently, the HEA filler reacted more sufficiently with diamonds, which contributed to improve the bonding strength and wear resistance of the brazed diamond. This work provided a new application scenario for HEAs as promising filler materials for brazing diamonds.","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141517726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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