Thermodynamics aided design of hBN-capsulated diboride powders from novel nitrate precursors for high entropy ceramics  

作　　者：Hailing Yang Ji Zou Zhimin Xiong Jingjing Liu Weimin Wang Zhengyi Fu 

机构地区：[1]State Key Laboratory of Advanced Technology for Materials Synthesis and Processing,Wuhan University of Technology,Wuhan 430070,China [2]School of Materials Science and Engineering,Wuhan University of Technology,Wuhan 430070,China [3]Hubei Longzhong Laboratory,Xiangyang 441000,China

出　　处：《Journal of Materials Science & Technology》2024年第11期133-142,共10页材料科学技术（英文版）

基　　金：National Natural Science Foundation of China(Nos.52022072,52332003,51972243,52293373 and 92060202);National Key R&D Programmer(No.2021YFB3701400);Hubei Provincial Natural Science Foundation of China(Distinguished Young Scholars 2022CFA042);Independent Innovation Projects of the Hubei Longzhong Laboratory(No.2022ZZ-10).

摘　　要：Hexagonal BN-coated powders have been widely used in various engineering sectors,however,their pro-ductions are restricted by the complexity of gas-solid reactions.In this study,guided by thermodynamics,a novel approach to synthesize Layer-structured hexagonal BN(hBN)-coated high entropy diboride pow-ders in vacuum was developed,using metal salt Zr(NO_(3))4·5H_(2)O,HfCl_(4),NbC_(15),TaC_(15),C_(16)H_(36)O_(4)Ti,boric acid,and sucrose as raw materials.By adjusting the ratio of carbon to metal source(C/M),powders only consisting of two boride solid solutions and hBN were finally obtained,under an optimal process-ing condition of C/M=5.5 and synthesis temperature of 1400 ℃.Parts of hBN were found to coat on high-entropy metal diborides ceramic(HEB)particles,corresponding formation mechanism for core-shell structured powders was investigated,together with the liquid precursor assisted boro/carbothermal re-duction process.Starting from as-synthesized core-shell powders,(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))B2-11 vol%hBN ceramics were densified at 1900 ℃ under 50 MPa without holding,with a high relative density of 97.3%.

关 键 词：High entropy boride Boro/carbothermal reduction Sol-gel Core-shell powders DENSIFICATION 

分 类 号：TQ174.1[化学工程—陶瓷工业]