Pub Date : 2024-11-15DOI: 10.1016/j.jeurceramsoc.2024.117078
Yan Zhang , Bo-Yu Ni , Yan-Fu Chai , Wei-Ming Guo , Tian-Qi Zhang , Wei-Feng Yao , Hua-Tay Lin
The oxidation behavior of (Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2 and (Hf0.2Zr0.2Ta0.2Cr0.2Ti0.2)B2 high entropy boride ceramics at 1200 °C was investigated to provide insights into their microstructural evolution and oxidation mechanism. The results showed that the oxide layer thickness of (Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2 was about 112 μm, much thicker than the counterpart of (Hf0.2Zr0.2Ta0.2Cr0.2Ti0.2)B2 (∼62 μm). The differences in oxidation response and oxidation resistance between these two material systems were mainly pertained to the generation of different structures of oxide layer. For the (Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2 sample, the oxide layer was composed of four-layer structure (porous-dense-porous-dense). In contrast, the oxide layers of (Hf0.2Zr0.2Ta0.2Cr0.2Ti0.2)B2 sample exhibited a distinctly laminated structure.
{"title":"Oxidation behavior of (Hf0.2Zr0.2Ta0.2Ti0.2Me0.2)B2 (Me=Nb,Cr) high-entropy ceramics at 1200 °C in air","authors":"Yan Zhang , Bo-Yu Ni , Yan-Fu Chai , Wei-Ming Guo , Tian-Qi Zhang , Wei-Feng Yao , Hua-Tay Lin","doi":"10.1016/j.jeurceramsoc.2024.117078","DOIUrl":"10.1016/j.jeurceramsoc.2024.117078","url":null,"abstract":"<div><div>The oxidation behavior of (Hf<sub>0.2</sub>Zr<sub>0.2</sub>Ta<sub>0.2</sub>Nb<sub>0.2</sub>Ti<sub>0.2</sub>)B<sub>2</sub> and (Hf<sub>0.2</sub>Zr<sub>0.2</sub>Ta<sub>0.2</sub>Cr<sub>0.2</sub>Ti<sub>0.2</sub>)B<sub>2</sub> high entropy boride ceramics at 1200 °C was investigated to provide insights into their microstructural evolution and oxidation mechanism. The results showed that the oxide layer thickness of (Hf<sub>0.2</sub>Zr<sub>0.2</sub>Ta<sub>0.2</sub>Nb<sub>0.2</sub>Ti<sub>0.2</sub>)B<sub>2</sub> was about 112 μm, much thicker than the counterpart of (Hf<sub>0.2</sub>Zr<sub>0.2</sub>Ta<sub>0.2</sub>Cr<sub>0.2</sub>Ti<sub>0.2</sub>)B<sub>2</sub> (∼62 μm). The differences in oxidation response and oxidation resistance between these two material systems were mainly pertained to the generation of different structures of oxide layer. For the (Hf<sub>0.2</sub>Zr<sub>0.2</sub>Ta<sub>0.2</sub>Nb<sub>0.2</sub>Ti<sub>0.2</sub>)B<sub>2</sub> sample, the oxide layer was composed of four-layer structure (porous-dense-porous-dense). In contrast, the oxide layers of (Hf<sub>0.2</sub>Zr<sub>0.2</sub>Ta<sub>0.2</sub>Cr<sub>0.2</sub>Ti<sub>0.2</sub>)B<sub>2</sub> sample exhibited a distinctly laminated structure.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"45 4","pages":"Article 117078"},"PeriodicalIF":5.8,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.jeurceramsoc.2024.117076
Bettina Osswald, Frank Kern
TZP starting powders containing 0.6 mol% each of yttria, dysprosia, gadolinia, samaria and neodymia stabilizer were fabricated by a wet chemical route by coating monoclinic zirconia with rare earth nitrates and subsequent calcination. The powders were consolidated by hot pressing in the temperature range between 1250 °C–1500 °C for 1 h at 60 MPa pressure. The materials were characterized with respect to microstructure, phase composition and mechanical properties. The materials combine high fracture toughness over the whole sintering temperature range with moderate hardness and attractive strength. XRD showed that a redistribution of stabilizers takes place during sintering, an initial highly tetragonal phase containing little or no stabilizer is successively eliminated and a stabilizer saturated tetragonal phase is progressively formed. The volume fraction of cubic increases with sintering temperature as the stabilizer content increases. Above 1500 °C, a plate-shaped aluminate phase is formed from the alumina sintering aid and rare earth oxide.
{"title":"Properties of multiple rare earth oxides co-stabilized YDyGdSmNd-TZP ceramics","authors":"Bettina Osswald, Frank Kern","doi":"10.1016/j.jeurceramsoc.2024.117076","DOIUrl":"10.1016/j.jeurceramsoc.2024.117076","url":null,"abstract":"<div><div>TZP starting powders containing 0.6 mol% each of yttria, dysprosia, gadolinia, samaria and neodymia stabilizer were fabricated by a wet chemical route by coating monoclinic zirconia with rare earth nitrates and subsequent calcination. The powders were consolidated by hot pressing in the temperature range between 1250 °C–1500 °C for 1 h at 60 MPa pressure. The materials were characterized with respect to microstructure, phase composition and mechanical properties. The materials combine high fracture toughness over the whole sintering temperature range with moderate hardness and attractive strength. XRD showed that a redistribution of stabilizers takes place during sintering, an initial highly tetragonal phase containing little or no stabilizer is successively eliminated and a stabilizer saturated tetragonal phase is progressively formed. The volume fraction of cubic increases with sintering temperature as the stabilizer content increases. Above 1500 °C, a plate-shaped aluminate phase is formed from the alumina sintering aid and rare earth oxide.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"45 4","pages":"Article 117076"},"PeriodicalIF":5.8,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.jeurceramsoc.2024.117079
Qi You , Zhongyang Wu , Yongjun Li , Ya Zhong , Sisi Shang , Man Yuan , Yichen Ou , Huanhuan Xu , Sheng Cui
Mullite aerogel is considered a promising candidate for thermal protection. However, structural collapse and poor temperature resistance limit its application at high temperature. Herein, amorphous SiOC-coated mullite aerogels (MAs) were prepared by high-temperature calcination, using Al2O3 nanorods and SiO2 particles as precursor units. The one-dimensional submicron skeleton prevents weak pearl chain connections and high surface energy, while the nanoscale amorphous SiOC layer protects the encapsulated mullite skeleton, ensuring a strong skeleton and pores at high temperatures. MAs exhibit a low thermal conductivity of 0.0375 W/(m·K) at room temperature, a robust compressive strength of 0.369 MPa, and good thermal stability: after 30 min of annealing at 1500 ℃, the minimal linear shrinkage of MAs was 0.72 %. Interestingly, the amorphous SiOC layer grew into nanowires under a butane flame, which reconstructed the network and impeded the heat flow. Thus, the novel MAs exhibit considerable thermal insulation advantages in harsh environments.
{"title":"Amorphous SiOC-coated submicron mullite aerogels with excellent thermal and structural stability up to 1500 ℃","authors":"Qi You , Zhongyang Wu , Yongjun Li , Ya Zhong , Sisi Shang , Man Yuan , Yichen Ou , Huanhuan Xu , Sheng Cui","doi":"10.1016/j.jeurceramsoc.2024.117079","DOIUrl":"10.1016/j.jeurceramsoc.2024.117079","url":null,"abstract":"<div><div>Mullite aerogel is considered a promising candidate for thermal protection. However, structural collapse and poor temperature resistance limit its application at high temperature. Herein, amorphous SiOC-coated mullite aerogels (MAs) were prepared by high-temperature calcination, using Al<sub>2</sub>O<sub>3</sub> nanorods and SiO<sub>2</sub> particles as precursor units. The one-dimensional submicron skeleton prevents weak pearl chain connections and high surface energy, while the nanoscale amorphous SiOC layer protects the encapsulated mullite skeleton, ensuring a strong skeleton and pores at high temperatures. MAs exhibit a low thermal conductivity of 0.0375 W/(m·K) at room temperature, a robust compressive strength of 0.369 MPa, and good thermal stability: after 30 min of annealing at 1500 ℃, the minimal linear shrinkage of MAs was 0.72 %. Interestingly, the amorphous SiOC layer grew into nanowires under a butane flame, which reconstructed the network and impeded the heat flow. Thus, the novel MAs exhibit considerable thermal insulation advantages in harsh environments.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"45 4","pages":"Article 117079"},"PeriodicalIF":5.8,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-14DOI: 10.1016/j.jeurceramsoc.2024.117074
Yunlei Lv , Yongsheng Liu , Binghui Zhang , Xiaokun Sun , Yejie Cao , Yaming Wu
High-density HfB2-SiC ceramics were prepared by reactive melt infiltration (RMI) at a relatively low temperature (1500°C). The ceramics had the open porosity of 0.5 % and the uniform distribution of constituent phases. The long-term oxidation behavior of HfB2-SiC ceramics in air was investigated at 1650°C. After oxidation for 100 h, the weight gain rates of ceramics varied within the range of 1.30–2.26 %. The oxidation products included SiO2, HfO2, and HfSiO4 phases, among which the HfSiO4 compound possessed the higher stability resulting from the reaction between the HfO2 and SiO2 phases. The samples all exhibited the typical feature of layered scale structure after HfB2-SiC oxidation, which was composed of the outermost SiO2 glass layer with the uneven thickness, followed by a relatively porous oxide layer containing white HfO2 and slight HfSiO4, below it was the unoxidized HfB2-SiC. The presence of this multiphase glass layer endowed the samples with excellent oxidation resistance.
{"title":"HfB2-SiC ceramics fabricated by reactive melt infiltration and its long-term oxidation behavior at 1650°C","authors":"Yunlei Lv , Yongsheng Liu , Binghui Zhang , Xiaokun Sun , Yejie Cao , Yaming Wu","doi":"10.1016/j.jeurceramsoc.2024.117074","DOIUrl":"10.1016/j.jeurceramsoc.2024.117074","url":null,"abstract":"<div><div>High-density HfB<sub>2</sub>-SiC ceramics were prepared by reactive melt infiltration (RMI) at a relatively low temperature (1500°C). The ceramics had the open porosity of 0.5 % and the uniform distribution of constituent phases. The long-term oxidation behavior of HfB<sub>2</sub>-SiC ceramics in air was investigated at 1650°C. After oxidation for 100 h, the weight gain rates of ceramics varied within the range of 1.30–2.26 %. The oxidation products included SiO<sub>2</sub>, HfO<sub>2</sub>, and HfSiO<sub>4</sub> phases, among which the HfSiO<sub>4</sub> compound possessed the higher stability resulting from the reaction between the HfO<sub>2</sub> and SiO<sub>2</sub> phases. The samples all exhibited the typical feature of layered scale structure after HfB<sub>2</sub>-SiC oxidation, which was composed of the outermost SiO<sub>2</sub> glass layer with the uneven thickness, followed by a relatively porous oxide layer containing white HfO<sub>2</sub> and slight HfSiO<sub>4</sub>, below it was the unoxidized HfB<sub>2</sub>-SiC. The presence of this multiphase glass layer endowed the samples with excellent oxidation resistance.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"45 4","pages":"Article 117074"},"PeriodicalIF":5.8,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-13DOI: 10.1016/j.jeurceramsoc.2024.117073
Xinru Nie , Ruiyi Jing , Yule Yang , Yangxi Yan , Vladimir Laletin , Vladimir Shur , Guan Wang , Li Jin
Lead-free (Bi0.5Na0.5)TiO3 (BNT)-based ceramics play a vital role in transducers and sensors, owing to their pronounced electrostrain response under applied electric fields. This work presents a notable electrostrain response of 0.54 % with minimal electrostrain hysteresis (11 %) in the x = 0.30 composition near the morphotropic phase boundary (MPB) within (1–x)BNT-x(Ba0.15Sr0.55Ca0.3)TiO3 (x = 0.2–0.4, BNT-xBSCT) ceramics. By exploiting the variation in tolerance factor through titanate doping and localized disorder from A-site multiple ion substitution, we achieved enhanced electrostrain response via the evolution of nonergodic relaxor (NR) and ergodic relaxor (ER) phase boundaries. Notably, the x = 0.30 composition exhibits ultrahigh electrostrain (>0.5 %) with remarkable thermal stability above 70 °C. This stability arises from the combined effects of domain flipping in ER/NR mixed phases and reversible electric field-induced relaxor-to-ferroelectric phase transitions. These results hold significant potential for advancing electrostrain performance and thermal stability in lead-free BNT-based ceramics.
无铅（Bi0.5Na0.5）TiO3（BNT）基陶瓷由于在外加电场作用下具有明显的电应变响应，因此在传感器和感应器中发挥着重要作用。这项研究在 (1-x)BNT-x(Ba0.15Sr0.55Ca0.3)TiO3 (x = 0.2-0.4, BNT-xBSCT)陶瓷的形态相边界 (MPB) 附近的 x = 0.30 成分中，发现了 0.54 % 的显著电应变响应和最小的电应变滞后 (11%)。通过利用钛酸盐掺杂带来的容限因子变化和 A 位多离子置换带来的局部无序，我们通过非极性弛豫体（NR）和极性弛豫体（ER）相界的演化增强了电应变响应。值得注意的是，x = 0.30 成分表现出超高的电应变（0.5%），在 70 °C 以上具有显著的热稳定性。这种稳定性源于 ER/NR 混合相中的畴翻转和可逆电场诱导的弛豫相到铁电相转变的共同作用。这些结果为提高无铅 BNT 基陶瓷的电应变性能和热稳定性提供了巨大的潜力。
{"title":"Optimized electrostrain with minimal hysteresis at the MPB in BNT-based ceramics","authors":"Xinru Nie , Ruiyi Jing , Yule Yang , Yangxi Yan , Vladimir Laletin , Vladimir Shur , Guan Wang , Li Jin","doi":"10.1016/j.jeurceramsoc.2024.117073","DOIUrl":"10.1016/j.jeurceramsoc.2024.117073","url":null,"abstract":"<div><div>Lead-free (Bi<sub>0.5</sub>Na<sub>0.5</sub>)TiO<sub>3</sub> (BNT)-based ceramics play a vital role in transducers and sensors, owing to their pronounced electrostrain response under applied electric fields. This work presents a notable electrostrain response of 0.54 % with minimal electrostrain hysteresis (11 %) in the <em>x</em> = 0.30 composition near the morphotropic phase boundary (MPB) within (1–<em>x</em>)BNT-<em>x</em>(Ba<sub>0.15</sub>Sr<sub>0.55</sub>Ca<sub>0.3</sub>)TiO<sub>3</sub> (<em>x</em> = 0.2–0.4, BNT-<em>x</em>BSCT) ceramics. By exploiting the variation in tolerance factor through titanate doping and localized disorder from A-site multiple ion substitution, we achieved enhanced electrostrain response via the evolution of nonergodic relaxor (NR) and ergodic relaxor (ER) phase boundaries. Notably, the <em>x</em> = 0.30 composition exhibits ultrahigh electrostrain (>0.5 %) with remarkable thermal stability above 70 °C. This stability arises from the combined effects of domain flipping in ER/NR mixed phases and reversible electric field-induced relaxor-to-ferroelectric phase transitions. These results hold significant potential for advancing electrostrain performance and thermal stability in lead-free BNT-based ceramics.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"45 4","pages":"Article 117073"},"PeriodicalIF":5.8,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-12DOI: 10.1016/j.jeurceramsoc.2024.117052
Aurélien Doitrand , Ronan Henry , Sylvain Meille
Sapphire fracture is studied by means of four-point bending tests on mirror-polished millimetric specimens having their crystallographic -axis oriented along the specimen length. The scattering of bending strengths between 500 MPa and 750 MPa is mainly due to edge defects of some tens of microns resulting from the specimen cutting process. Crack initiation occurs from an edge defect along a a-plane, perpendicular to the direction of maximum tensile stress, and further deviates along weaker m-planes. Numerical simulations of edge defect-induced crack initiation based on the coupled criterion reveal that the material sensitivity to edge defect-induced crack initiation mainly depends on Irwin’s length. For Irwin’s lengths larger than twice the defect depth, the bending strength is the same as the one obtained without defect. By retrieving the bending strength variation as a function of the defect depth measured experimentally, the proposed approach enables the identification of sapphire a-plane tensile strength for a critical energy release rate.
通过对镜面抛光毫米级试样进行四点弯曲试验，研究了蓝宝石的断裂情况，试样的晶体学 a→ 轴沿试样长度方向。弯曲强度在 500 兆帕和 750 兆帕之间的分散主要是由于试样切割过程中产生的数十微米的边缘缺陷造成的。裂纹从垂直于最大拉伸应力方向的 a 平面的边缘缺陷开始，并进一步偏离较弱的 m 平面。基于耦合准则的边缘缺陷诱发裂纹起始数值模拟显示，材料对边缘缺陷诱发裂纹起始的敏感性主要取决于 Irwin 长度。当 Irwin 长度大于缺陷深度的两倍时，弯曲强度与无缺陷时相同。通过检索作为实验测量的缺陷深度函数的弯曲强度变化，所提出的方法能够确定 Gc=15Jm-2 临界能量释放率下蓝宝石 a 平面 850±90MPa 的抗拉强度。
{"title":"Explanation of edge defect influence on sapphire bending strength scatter using the coupled criterion","authors":"Aurélien Doitrand , Ronan Henry , Sylvain Meille","doi":"10.1016/j.jeurceramsoc.2024.117052","DOIUrl":"10.1016/j.jeurceramsoc.2024.117052","url":null,"abstract":"<div><div>Sapphire fracture is studied by means of four-point bending tests on mirror-polished millimetric specimens having their crystallographic <span><math><mover><mrow><mi>a</mi></mrow><mo>→</mo></mover></math></span>-axis oriented along the specimen length. The scattering of bending strengths between 500<!--> <!-->MPa and 750<!--> <!-->MPa is mainly due to edge defects of some tens of microns resulting from the specimen cutting process. Crack initiation occurs from an edge defect along a a-plane, perpendicular to the direction of maximum tensile stress, and further deviates along weaker m-planes. Numerical simulations of edge defect-induced crack initiation based on the coupled criterion reveal that the material sensitivity to edge defect-induced crack initiation mainly depends on Irwin’s length. For Irwin’s lengths larger than twice the defect depth, the bending strength is the same as the one obtained without defect. By retrieving the bending strength variation as a function of the defect depth measured experimentally, the proposed approach enables the identification of sapphire a-plane <span><math><mrow><mn>850</mn><mo>±</mo><mn>90</mn><mspace></mspace><mstyle><mi>M</mi><mi>P</mi><mi>a</mi></mstyle></mrow></math></span> tensile strength for a <span><math><mrow><msub><mrow><mi>G</mi></mrow><mrow><mi>c</mi></mrow></msub><mo>=</mo><mn>15</mn><mspace></mspace><mstyle><mi>J</mi></mstyle><mspace></mspace><msup><mrow><mstyle><mi>m</mi></mstyle></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></mrow></math></span> critical energy release rate.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"45 4","pages":"Article 117052"},"PeriodicalIF":5.8,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-09DOI: 10.1016/j.jeurceramsoc.2024.117068
Liuchao Zhang , Fa Luo , Yingying Zhou , Yaru Cao , Qian Zhang , Chunhai Wang , Yuqin Li , Yuchang Qing
The thermal radiation properties of plasma spraying thermal barrier coatings (TBCs), primarily governed by splat thickness distribution and pore structure, significantly affect its thermal insulation performance. To enhance thermal radiation blocking while preserving mechanical strength, TBCs featuring a bimodal splat thickness distribution were designed and prepared. This structure was achieved by incorporating the innovatively prepared ultra-thin hollow YSZ powders, coated with carbon film, during plasma spraying. The inclusion of thinner splats effectively enhances the scattered electromagnetic filed, increasing the average scattering coefficients from 30475 to 41225 m−1 compared to conventional TBCs. Consequently, modeling shows the substrate temperature during service decreased by up to 57.2 K, markedly improving thermal insulation of TBCs. Importantly, mechanical properties, including Young’s modulus and microhardness, experienced only minor reductions due to the structural support provided by thicker splats. These results underscore the potential of bimodal splat thickness distribution structure in advancing the performance of TBCs.
{"title":"Enhanced thermal radiation blocking of plasma spraying thermal barrier coatings with a bimodal splat thickness distribution","authors":"Liuchao Zhang , Fa Luo , Yingying Zhou , Yaru Cao , Qian Zhang , Chunhai Wang , Yuqin Li , Yuchang Qing","doi":"10.1016/j.jeurceramsoc.2024.117068","DOIUrl":"10.1016/j.jeurceramsoc.2024.117068","url":null,"abstract":"<div><div>The thermal radiation properties of plasma spraying thermal barrier coatings (TBCs), primarily governed by splat thickness distribution and pore structure, significantly affect its thermal insulation performance. To enhance thermal radiation blocking while preserving mechanical strength, TBCs featuring a bimodal splat thickness distribution were designed and prepared. This structure was achieved by incorporating the innovatively prepared ultra-thin hollow YSZ powders, coated with carbon film, during plasma spraying. The inclusion of thinner splats effectively enhances the scattered electromagnetic filed, increasing the average scattering coefficients from 30475 to 41225 m<sup>−1</sup> compared to conventional TBCs. Consequently, modeling shows the substrate temperature during service decreased by up to 57.2 K, markedly improving thermal insulation of TBCs. Importantly, mechanical properties, including Young’s modulus and microhardness, experienced only minor reductions due to the structural support provided by thicker splats. These results underscore the potential of bimodal splat thickness distribution structure in advancing the performance of TBCs.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"45 3","pages":"Article 117068"},"PeriodicalIF":5.8,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-09DOI: 10.1016/j.jeurceramsoc.2024.117065
Juan-Nan Chen , Xuan-Zhe Pei , Qian Wang , Xian Zhao , Ze-Yan Wang , Chun-Ming Wang
Calcium bismuth niobate (CaBi2Nb2O9) is a promising ceramic material for high-temperature piezoelectric applications due to its high Curie temperature (TC) of 940 °C. However, its practical use is limited by poor piezoelectric performance and low direct-current (DC) electrical resistivity at elevated temperatures. In this study, we introduced pseudo-tetragonal distortion into CaBi2Nb2O9 by substituting rare-earth thulium ions, which reduced domain wall energy, facilitated domain switching, and decreased the presence of oxygen vacancies. These enhancements significantly improved both the piezoelectric performance and DC electrical resistivity of the material. To further enhance piezoelectric performance, we prepared textured thulium-substituted CaBi2Nb2O9 ceramics with a Lotgering factor (f) of up to 77.4 % using a two-step spark plasma sintering method. The resulting textured CaBi2Nb2O9 ceramics exhibited superior piezoelectric performance, with a piezoelectric constant d33 of 25.2 pC/N, four times higher than that of non-textured CaBi2Nb2O9. Importantly, these textured ceramics maintained excellent electrical properties at elevated temperatures, suggesting their suitability for high-temperature piezoelectric device applications.
{"title":"Spark plasma sintering of high-TC calcium bismuth niobate (CaBi2Nb2O9) with superior piezoelectric performance","authors":"Juan-Nan Chen , Xuan-Zhe Pei , Qian Wang , Xian Zhao , Ze-Yan Wang , Chun-Ming Wang","doi":"10.1016/j.jeurceramsoc.2024.117065","DOIUrl":"10.1016/j.jeurceramsoc.2024.117065","url":null,"abstract":"<div><div>Calcium bismuth niobate (CaBi<sub>2</sub>Nb<sub>2</sub>O<sub>9</sub>) is a promising ceramic material for high-temperature piezoelectric applications due to its high Curie temperature (<em>T</em><sub>C</sub>) of 940 °C. However, its practical use is limited by poor piezoelectric performance and low direct-current (DC) electrical resistivity at elevated temperatures. In this study, we introduced pseudo-tetragonal distortion into CaBi<sub>2</sub>Nb<sub>2</sub>O<sub>9</sub> by substituting rare-earth thulium ions, which reduced domain wall energy, facilitated domain switching, and decreased the presence of oxygen vacancies. These enhancements significantly improved both the piezoelectric performance and DC electrical resistivity of the material. To further enhance piezoelectric performance, we prepared textured thulium-substituted CaBi<sub>2</sub>Nb<sub>2</sub>O<sub>9</sub> ceramics with a Lotgering factor (<em>f</em>) of up to 77.4 % using a two-step spark plasma sintering method. The resulting textured CaBi<sub>2</sub>Nb<sub>2</sub>O<sub>9</sub> ceramics exhibited superior piezoelectric performance, with a piezoelectric constant <em>d</em><sub>33</sub> of 25.2 pC/N, four times higher than that of non-textured CaBi<sub>2</sub>Nb<sub>2</sub>O<sub>9</sub>. Importantly, these textured ceramics maintained excellent electrical properties at elevated temperatures, suggesting their suitability for high-temperature piezoelectric device applications.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"45 4","pages":"Article 117065"},"PeriodicalIF":5.8,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-09DOI: 10.1016/j.jeurceramsoc.2024.117066
Shuo Song, Rong Ma, Tongyao Pang, Min Xi, Dongmei Wang, Weiwei Zhao, Weixing Zhao, Zhuonan Huang, Dengwei Hu
A novel core-shell structured Ba0.99Bi0.01TiO3@xMnO (BBT@MnO) (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 mol%) relaxation ferroelectric ceramics were prepared by co-precipitation method. The structures, insulating, dielectric, and energy storage properties of the BBT@MnO ceramics were systematically investigated. According to TEM, the particles had a diameter of about 430 nm, high uniformity, and high dispersity. They were fabricated using a coating technique to simultaneously improve both the dielectric breakdown strength (BDS) and densification of the ceramics. The thickness of the MnO layers in the BBT@MnO particles averaged about 19 nm. Complex impedance testing of BBT@MnO ceramics revealed that only a one-grain boundary response existed for all ceramics, with the best insulating properties at x = 0.4 mol%. Furthermore, MnO coating increased lattice distortion and polarization intensity, altering the crystal structure and microstructure morphology while increasing energy storage density. The ceramics with 0.4 mol% MnO coating showed thin P-E hysteresis loops, with an optimal dielectric constant of 3610, a dielectric loss of 0.01, and the discharged energy density (Jd) of 0.26 J/cm3 and efficiency (η) of 76.5 %. The results showed that MnO coating is beneficial for reducing dielectric loss and improving insulation performance. This study provided valuable insights for the research of lead-free dielectric ceramic capacitors, and the BBT@MnO ceramics present good development prospects in high-power pulse energy storage systems.
{"title":"High energy storage capacity and relaxation ferroelectric characteristics of fine-grained Ba0.99Bi0.01TiO3@MnO core-shell nanoceramics","authors":"Shuo Song, Rong Ma, Tongyao Pang, Min Xi, Dongmei Wang, Weiwei Zhao, Weixing Zhao, Zhuonan Huang, Dengwei Hu","doi":"10.1016/j.jeurceramsoc.2024.117066","DOIUrl":"10.1016/j.jeurceramsoc.2024.117066","url":null,"abstract":"<div><div>A novel core-shell structured Ba<sub>0.99</sub>Bi<sub>0.01</sub>TiO<sub>3</sub>@xMnO (BBT@MnO) (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 mol%) relaxation ferroelectric ceramics were prepared by co-precipitation method. The structures, insulating, dielectric, and energy storage properties of the BBT@MnO ceramics were systematically investigated. According to TEM, the particles had a diameter of about 430 nm, high uniformity, and high dispersity. They were fabricated using a coating technique to simultaneously improve both the dielectric breakdown strength (<em>BDS</em>) and densification of the ceramics. The thickness of the MnO layers in the BBT@MnO particles averaged about 19 nm. Complex impedance testing of BBT@MnO ceramics revealed that only a one-grain boundary response existed for all ceramics, with the best insulating properties at x = 0.4 mol%. Furthermore, MnO coating increased lattice distortion and polarization intensity, altering the crystal structure and microstructure morphology while increasing energy storage density. The ceramics with 0.4 mol% MnO coating showed thin <em>P-E</em> hysteresis loops, with an optimal dielectric constant of 3610, a dielectric loss of 0.01, and the discharged energy density (<em>J</em><sub><em>d</em></sub>) of 0.26 J/cm<sup>3</sup> and efficiency (<em>η</em>) of 76.5 %. The results showed that MnO coating is beneficial for reducing dielectric loss and improving insulation performance. This study provided valuable insights for the research of lead-free dielectric ceramic capacitors, and the BBT@MnO ceramics present good development prospects in high-power pulse energy storage systems.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"45 3","pages":"Article 117066"},"PeriodicalIF":5.8,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An innovative nuclear fuel doped with a redox buffer is being developed to control the partial oxygen pressure (pO2) within the reactor and thereby limit stress corrosion cracking of the cladding. The selected redox buffer couple is Nb2O5/NbO2. The doping of the fuel affects its densification and final properties. Therefore, a study is being conducted on the densification behavior of this type of fuel and the influence of dopant concentration. The dopant was mixed with UO2, and the powder was then pressed into pellets, sintered under a reducing atmosphere. The linear shrinkage and oxygen release from the pellet were monitored during sintering. This method highlighted the reduction of niobium oxides during sintering, which causes oxygen release, influencing the densification behavior and microstructure of the doped fuel.
{"title":"Sintering behaviour of buffered UO2 fuel doped with niobium oxides","authors":"Shalane Gobert , Fabienne Audubert , Jean-Marc Heintz","doi":"10.1016/j.jeurceramsoc.2024.117049","DOIUrl":"10.1016/j.jeurceramsoc.2024.117049","url":null,"abstract":"<div><div>An innovative nuclear fuel doped with a redox buffer is being developed to control the partial oxygen pressure (pO<sub>2</sub>) within the reactor and thereby limit stress corrosion cracking of the cladding. The selected redox buffer couple is Nb<sub>2</sub>O<sub>5</sub>/NbO<sub>2</sub>. The doping of the fuel affects its densification and final properties. Therefore, a study is being conducted on the densification behavior of this type of fuel and the influence of dopant concentration. The dopant was mixed with UO<sub>2</sub>, and the powder was then pressed into pellets, sintered under a reducing atmosphere. The linear shrinkage and oxygen release from the pellet were monitored during sintering. This method highlighted the reduction of niobium oxides during sintering, which causes oxygen release, influencing the densification behavior and microstructure of the doped fuel.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"45 4","pages":"Article 117049"},"PeriodicalIF":5.8,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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