Abstract: To develop self-toughened SiC-B₄C-ZrB₂ multiphase ceramics with superior mechanical properties,specimens were fabricated via pressureless solid-state sintering at 2 200 ℃ for 2 h using SiC,B₄C,ZrO₂,and graphite micropowder as raw materials.The effects of ZrO₂ additions (0,5.60%,10.90%,15.93%,20.69%,and 25.25%,by mass) on the microstructure and mechanical properties of the ceramics were investigated.Key findings include:(1)the addition of ZrO₂ is conducive to sintering densification and the anisotropic growth of SiC grains,forming a unique multimodal grain interlocking microstructure,which significantly improves the damage tolerance of the material;(2)with the increase of ZrO₂ addition,the relative density,flexural strength and hardness of the samples show a trend of first increasing and then decreasing;when the ZrO₂ addition is 10.90%,the relative density is the highest,up to 98.23%,and the Vickers hardness and flexural strength reach the peaks,29.7 GPa and 443 MPa,respectively;in addition,when the ZrO₂ addition is 15.93%,the sample shows the highest fracture toughness of 6.43 MPa·m^1/2.

Key words: pressureless sintering, multiphase ceramics, microstructure, mechanical properties

摘要： 为了制备具有优异力学性能的自增韧SiC-B₄C-ZrB₂复相陶瓷,以SiC、B₄C、ZrO₂和石墨碳微粉为原料,通过无压固相烧结经2 200 ℃保温2 h制备SiC-B₄C-ZrB₂复相陶瓷,研究了不同ZrO₂加入量(加入质量分数分别为0、5.60%、10.90%、15.93%、20.69%和25.25%)对复相陶瓷显微结构和力学性能的影响。结果表明:1)ZrO₂的添加有助于烧结致密化,并促进SiC晶粒异向生长,形成了独特的多模态晶粒互锁显微结构,显著提升材料的损伤容限。2)随着ZrO₂加入量的增加,试样相对密度、弯曲强度和硬度呈现先增加后减小的趋势,当ZrO₂加入量为10.90%(w)时,相对密度最高,可达98.23%,维氏硬度和弯曲强度达到峰值,分别为29.7 GPa和443 MPa。此外,ZrO₂加入量为15.93%(w)时,试样展现出最高的断裂韧性,可达6.43 MPa·m^1/2。

关键词: 无压烧结, 复相陶瓷, 显微结构, 力学性能