The Study Of BN-SiC Amorphous Ceramic Powder Preparation

BN-SiC is a material that has many good characteristics, such as: thermostability;corrosion resisting; high heat conduction; high insulating property, and it is lighter thanSiC in the same size. So BN-SiC composite ceramic (BN is the matrix, nanometer SiCis the enhance phase) has a broad application prospects in the aerospace materials.Under the traditional sintering process, since BN and SiC are both the covalent bondceramics, if we use directly BN and SiC as the raw materials, the sinteringtemperature is high, and it is difficult to sintered density. So, the main purpose of thisessay is to prepare the Amorphous BN-SiC composite ceramic powers which has highersintering activity to reduce the sintering temperature. This essay use two kinds ofmethods (mechanical blending and polymer network) to prepare amorphous BN-SiCcomposite ceramic powers. The main content of this essay is:Based on the BN-SiC(Amorphous composite ceramic powers) that synthesis under1400-1500℃through mechanical blending, the best temperature is1450℃. Based onthe BN-SiC (Amorphous composite ceramic powers) that synthesis under1350-1450℃through polymer network, the influence of aging time, the yield of water, monomer andsynthesis temperature; and the synthesis mechanism of BN-SiC(Amorphous compositeceramic powers) was researched. The colloid of precursor and powder of the BN-SiCwere characterized by XRD, SEM,TEM, and HRTEM.The result shows that: compared with mechanical blending can not obtain theBN-SiC(Amorphous composite ceramic powers), the polymer network can get it, thisalso is the new innovation point in this research. Under this experimental condition, inorder to ensure the mixing each element in the material, we found that: the best againgtime is48h, the best water yiled is120ml, the best scope of monomer content is14.1wt.%-19.3wt.%, the best temperature is1400℃(heating for3h). The proportion ofboron and boric acid is1:2, the high quality BN-SiC amorphous powder will be got.And the shape of the powder is ball, it will help to educe the sintering temperature, topromote the popularization and application of BN-SiC composite ceramic.