Design strategy of phase and microstructure of Si_(3)N_(4) ceramics with simultaneously high hardness and toughness  

作　　者：Shao-Jun TANG Wei-Ming GUO Shi-Kuan SUN Hua-Tay LIN 

机构地区：[1]School of Electromechanical Engineering,Guangdong University of Technology,Guangzhou 510006,China [2]School of Material Science and Energy Engineering,Foshan University,Foshan 528000,China

出　　处：《Journal of Advanced Ceramics》2023年第1期122-131,共10页先进陶瓷（英文）

基　　金：supported by the Shandong Provincial Key Research and Development Program (2019JZZY010330);the National Natural Science Foundation of China (52172066 and 52172064);the Key Research and Development Project of Gansu Province (21YF5WA140);the Science and Technology Program of Guangzhou (201704030095);Shi-Kuan Sun acknowledges the Guangdong Key Platform&Programs of the Education Department of Guangdong Province (2021ZDZX1003);the Opening Project of State Key Laboratory of High Performance Ceramics and Superfine Microstructure (SKL202104SIC).

摘　　要：Aiming to achieve silicon nitride( Si_(3)N_(4))ceramics with high hardness and high toughness,the relationships among phase composition,microstructure,and mechanical properties of Si_(3)N_(4) ceramics prepared by spark plasma sintering(SPS)at temperatures ranging from 1500 to 1800℃were investigated in this study.Two stages with different phase and microstructure features were observed and summarized.Theα-βphase transformation occurs first,and the development and growth of grains lag behind.During the first stage,the average grain size remains basically unchanged,and the hardness maintains at a value of~20.18±0.26 GPa,despite theβ- Si_(3)N_(4) phase fraction increases from 7.67 to 57.34 wt%.Subsequently,the equiaxed grains transform into rod-like grains with a high aspect ratio via the reprecipitation process,resulting in a significant increase in the fracture toughness from 3.36±0.62 to 7.11±0.15 MPa·m^(1/2).In the second stage of sintering process,the fraction ofβ- Si_(3)N_(4) phase increases to 100.00 wt%,and the grain growth also rapidly occurs.Thus,the fracture toughness increases slightly to 7.61±0.42 MPa·m^(1/2),but the hardness reduces to 16.80±0.20 GPa.The current results demonstrate that the phase contents ofβ- Si_(3)N_(4) and the microstructure shall be carefully tailored to achieve high-performance Si_(3)N_(4) ceramics. Si_(3)N_(4) ceramics with a finegrained bimodal microstructure,consisting of the mainα-andβ-phases,can exhibit the optimized combination of hardness and toughness.

关 键 词：silicon nitride(Si_(3)N_(4)) phase composition MICROSTRUCTURE HARDNESS TOUGHNESS 

分 类 号：TQ174.1[化学工程—陶瓷工业]