The Study Of BN-SiC Composite Ceramic Material By Hot-Pressing Sintering Based On Sol-Gel Method

In this paper,We made two Two kinds of BN-SiC composite powders by the sol gel method and mechanical mixture.The BN as substrate,the mass fraction is less than50% SiC as the second phase and toughening phase mass distribute into the BN substrate.Then these composite powders were used for the preparation of BN-SiC composite ceramic by hot-pressing sintering method.During the material sintering performance and mechanical performance exploration,we used some equipments like CMT-100 type electronic universal testing machine,5 type hv/HVS vickers hardness tester,S4800 scanning electron microscope(SEM)etc.We explore the sintering temperature,holding time,the second phase content and the original powder properties of composite material by composite material density,vickers hardness,bending strength and microstructure analysis and research.For BN-SiC duplex ceramic material foundation for practical application.Purpose is for BN-SiC duplex ceramic material foundation for practical application.The experimental results show that BN-SiC composite powder by Sol gel method has high activation performance and lower sintering temperature.In the actual process of hot pressing sintering,we selected several temperature point(1700? ? 1750? ?1800?),we found that 1750 ? is the best sintering temperature of the material.At this time,the ceramic material absolute density and relative density were 1.69 g/cm3and68.79%.Material corresponding vickers hardness and bending strength were 16.24 MPa and 61.00 MPa.We also found that this series of BN-SiC duplex ceramic material the best second phase mass fraction of 20% wt.%,the best heat preservation time of 90 min.At this point,the BN-20% wt.% of composite ceramic materials absolute density and relative density of 2.13 g/cm3 and 86.84%.Material corresponding vickers hardness and bending strength were 47.68 MPa and 124.63 MPa.This paper also to the original powder preparation methods of BN-SiC duplex ceramics sintering performance impact was studied.In the sintering process is consistent(the best sintering conditions of 1750 ? x 1750 min,30 MPa),composite ceramic bySol gel method material grain size is small,low porosity,high degree of density.Mechanical mixing method,by contrast,composite ceramic materials occurring within the serious phenomenon of reunion.Therefore,by hot pressing and sintering of powders were prepared by sol gel after preparation of the composite ceramic material properties are better than mechanical mixing method.Compared with the mechanical mixing method,sol gel method is more suitable for as sintering high-performance BN-SiC composite ceramic material of the original powder preparation method.