B_(4)C含量对(Ti_(0.25)Zr_(0.25)Hf_(0.25)Ta_(0.25))B_(2)-B_(4)C陶瓷力学性能及抗氧化性能的影响  

Effect of B_(4)C Content on Mechanical Properties and Oxidation Resistance of(Ti_(0.25)Zr_(0.25)Hf_(0.25)Ta_(0.25))B_(2)-B_(4)C Ceramics

作　　者：刘国昂 王海龙[1] 方成 黄飞龙 杨欢 LIU Guoang;WANG Hailong;FANG Cheng;HUANG Feilong;YANG Huan(School of Materials Science and Engineering,Zhengzhou University,Zhengzhou 450001,China)

机构地区：[1]郑州大学材料科学与工程学院,郑州450001

出　　处：《无机材料学报》2024年第6期697-706,共10页Journal of Inorganic Materials

基　　金：国家自然科学基金(U23A20562,52172075,52302074);河南省杰出青年基金(202300410355);河南省高校科技创新团队支持计划(23IRTSTHN001);河南省自然科学基金(232300421323);中国博士后科学基金(2021M702931)。

摘　　要：新型高熵硼化物陶瓷具有优异的高温稳定性、低热导率等优点,在高温热防护领域具有广阔的应用前景。本研究采用硼/碳热还原法结合热压烧结技术在1900℃下制备了(Ti_(0.25)Zr_(0.25)Hf_(0.25)Ta_(0.25))B_(2)-B_(4)C高熵硼化物陶瓷,并研究了B_(4)C第二相含量对其力学及抗氧化性能的影响规律。结果表明,B_(4)C均匀分布在高熵基体中,有效改善了高熵陶瓷的相对密度和力学性能。当B_(4)C体积分数为20%时,复相陶瓷的抗弯强度、断裂韧性以及维氏硬度均达到最高,分别为(570.0±27.6)MPa、(5.58±0.36)MPa·m^(1/2)和(24.6±1.1)GPa。微观结构分析表明,B_(4)C能够钉扎晶界、细化晶粒,并能够引入裂纹偏转、分支等增韧机制,最终实现复相陶瓷的强化及韧化。此外,利用静态氧化实验,揭示了B_(4)C含量对复相陶瓷800~1400℃抗氧化性能的影响。当B_(4)C体积分数不小于20%时,其氧化生成的玻璃相B_(2)O_(3)能够均匀包裹(Zr,Hf)O_(2)、TiO_(x)及Ta_(2)O_(5)等高熵基体对应的氧化物,从而在陶瓷表面形成均匀致密的氧化层,抑制氧向基体内部扩散,降低氧化层厚度并提升复相陶瓷的抗氧化性能。本工作能够为高熵硼化物陶瓷的力学及抗氧化性能研究提供实验依据和数据支撑。High-entropy boride ceramics(HEBs)consisting of four or more principle metallic elements rapidly develop in recent years due to their outstanding unique physical properties and excellent elevated temperature properties,showing extraordinary promise as potential thermal protection materials applied in extreme environments.However,on the basis of unclear role of each element on their oxidation reaction,HEBs are generally difficult to densify because of their low self-diffusion coefficients and possible sluggish diffusion effect,resulting in limited mechanical properties and low oxidation resistance.In this work,a novel type of HEBs,(Ti_(0.25)Zr_(0.25)Hf_(0.25)Ta_(0.25))B_(2)-B_(4)C composites,were prepared by boro/carbothermal reduction method combined with hot-pressing sintering at 1900℃.The effect of B_(4)C at the volume fractions ranging from 10%to 30%on the mechanical properties and oxidation resistance of the composites was systematically investigated.Microstructure analyses indicate that homogenously distributed B_(4)C can suppress grain growth of the HEBs matrix and promote toughening mechanisms such as crack deflection and crack branching,consequently resulting in strengthening and toughening composites.When the volume fraction of B_(4)C is 20%,the as-prepared composite shows a high relative density(96.1%)and good mechanical properties with Vickers hardness of(24.6±1.1)GPa,flexural strength of(570.0±27.6)MPa and fracture toughness of(5.58±0.36)MPa·m^(1/2).In addition,exploration on the oxidation resistance of(Ti_(0.25)Zr_(0.25)Hf_(0.25)Ta_(0.25))B_(2)-B_(4)C composites at temperatures ranging from 800℃to 1400℃shows that excellent oxidation resistance occurs at the chosen temperatures due to the formation of a dense and continuous oxidation scale,which acts as a barrier layer preventing oxygen inward diffusion.The main compositions of the oxide scale are TiO_(x),(Zr,Hf)O_(2)oxides and B_(2)O_(3)at 800℃,while multicomponent oxidation products of(Zr,Hf,Ta)O_(x),(Zr,Hf)O_(2)and TiTaO_(4)are formed i

关 键 词：高熵硼化物陶瓷 B_(4)C 力学性能 抗氧化性能 

分 类 号：TQ174[化学工程—陶瓷工业]