期刊
INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY
卷 -, 期 -, 页码 -出版社
WILEY
DOI: 10.1111/ijac.14586
关键词
microstructure and mechanical properties; phase composition; Si nitridation and hot-pressing; Si3N4; ZrB2
The addition of ZrB2 in Si3N4 ceramics enhanced the transformation of alpha-Si3N4 into beta-Si3N4 phase and increased fracture toughness but decreased Vickers hardness. However, excessive ZrB2 content resulted in the formation of equiaxed coarse beta-Si3N4 grains and a significant decrease in Vickers hardness and fracture toughness.
This work investigated the effect of ZrB2 content on phase composition, relative density, microstructure, and mechanical performance of Si3N4 ceramics prepared by Si nitridation and hot-pressing method. Si3N4 ceramics were fabricated using Si powder by nitridation and hot-pressing process. Results showed that the addition of ZrB2 enhanced the transformation of alpha-Si3N4 into beta-Si3N4 phase during nitridation, resulting in a greater fraction of beta-Si3N4 (above 90 wt.%) phase in Si3N4 ceramics with ZrB2 after hot-pressing. In contrast, ceramics without ZrB2 had a lower ratio of beta-Si3N4 (40.4 wt.%). The use of 2.5 vol.% ZrB2 yielded a significant bimodal microstructure and increased fracture toughness to 5.0 +/- 0.2 MPam(1/2), but decreased Vickers hardness to 16.4 +/- 0.5 GPa. However, increasing the ZrB2 content to 5 vol.% and 10 vol.% led to a massive formation of equiaxed coarse beta-Si3N4 grains and a significant decrease in Vickers hardness and fracture toughness.
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