Study on the preparation technology and high temperature oxidation characteristics of SiB₄ powders

Abstract

High purity SiB4 powder is the key raw materials for high temperature resistant coating of rigid ceramic insulating tile, which plays the role of forming a dense coating and self-healing in the coating. Therefore, to obtain SiB4 powders with high performance and high purity at the same time can solve the problem of raw materials for high temperature resistant coating in China. However, the preparation process of SiB4 powder is complex, and no domestic manufacturer can produce it, which greatly limits the development of related industries in China. The relationship between SiB4 phase purity and boron-silicon ratio of raw materials, particle size and sintering process parameters in the synthesis of high-purity SiB4 powders was explored. The experimental results show that the yield of SiB4 can be significantly improved and the decomposition of SiB4 can be inhibited by adjusting the crystallinity of boron powder, particle size of raw material, sintering process parameters and the ratio of boron to silicon. When 1μm boron powder and 1μm silicon powder are used, the ratio of boron to silicon is 3.5:1, and the sintering process is 1320 °C - 2h, the high purity sib4 powder with only SiB4 phase detected by XRD phase analysis can be prepared after acid washing. On this basis, the high temperature oxidation characteristics of the prepared SiB4 powder were studied. The experimental results show that SiB4 powder can be oxidized at 1100 °C to form B2O3-SiO2 glass phase, which proves that it has better high temperature oxidation performance. In conclusion, it was proved that the prepared SiB4 powder had high purity and excellent high temperature resistance, which could be used for further production research.