Microstructural evolution and mechanical properties of h-BN composite ceramics with Y2O3–AlN addition by liquid-phase sintering

• Published in: Rare metals 2020-05, Vol.39 (5), p.555-561
• Main Authors: Qiu, Bao-Fu, Duan, Xiao-Ming, Zhang, Zhuo, Liao, Xing-Qi, Yang, Zhi-Hua, Cai, De-Long, Jia, De-Chang, Zhou, Yu
• Format: Article
• Language: English
• Subjects: Biomaterials; Boron nitride; Ceramics; Chemistry and Materials Science; Energy; Evolution; Grains; Hot pressing; Inflection points; Liquid phase sintering; Liquid phases; Materials Engineering; Materials Science; Mechanical properties; Metallic Materials; Microstructure; Nanoscale Science and Technology; Physical Chemistry; Porosity; Solid phases; Thermal diffusion; Wettability; Yttrium oxide
• ISSN: 1001-0521; 1867-7185
• DOI: 10.1007/s12598-019-01338-8

Hexagonal boron nitride (h-BN) composite ceramics were prepared by hot pressing with the addition of Y 2 O 3 and AlN. The effects of different Y 2 O 3 –AlN contents on microstructural evolution, mechanical properties and thermal diffusion coefficients of h-BN composite ceramics were investigated. The results indicate that Y 2 O 3 –AlN forms a liquid phase during the sintering process, achieving a good wettability with h-BN grains. In pure h-BN ceramic and h-BN composite ceramic with 40 wt% Y 2 O 3 –AlN, the h-BN grains grow well when controlled through solid-phase and liquid-phase diffusion, respectively. With the increase in Y 2 O 3 –AlN content, mechanical properties and thermal diffusion coefficients of h-BN composite ceramics first decrease and then increase, and the properties of h-BN composite ceramic with 10 wt% Y 2 O 3 –AlN are the inflection points. Such properties are highly related to the phase compositions, porosity and microstructure. Graphic abstract