Preparation And Characterization Of SiB₄ And RCG Powders For High Temperature Thermal-protective Coating

High purity SiB4 powder and RCG glass powder are the key raw materials for high temperature resistant coating of rigid ceramic insulating tile.In the existing coating powder,the preparation process of SiB4 powder and RCG glass powder is complex,and no domestic manufacturer can produce them,which greatly limits the development of related industries in China.At the same time,because the two kinds of powders exist as an organic whole in the process of coating preparation and use,they play the role of forming a dense coating and self-healing in the coating.Therefore,to obtain two kinds of 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.In this paper,based on the previous work of the research group,the process control of the preparation of SiB4 powder and RCG powder was studied,and the physical properties and properties of the prepared powder were characterized.It was proved that the prepared SiB4 and RCG powder had high purity and excellent high temperature resistance,which could be used for further production research.The main research work of this paper is as follows(1)The preparation parameters and properties of SiB4 powder were studied.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 1 ?m boron powder and 1 ?m silicon powder are used,the ratio of boron to silicon is 3.5:1,and the sintering process is 1320?-2 h,the SiB4 powder with purity greater than 98%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? to form B2O3-SiO2 glass phase,which proves that it has better high temperature oxidation performance.(2)The process control of RCG powder preparation was studied.The experimental results show that there is a linear relationship between the content of boron oxide in RCG powder and the addition amount,and the content of boron oxide in RCG powder increases slightly with the increase of sintering temperature.The core-shell structure RCG powders with core boron oxide content of 3.8-4.5%and shell boron oxide content of 9.4-11.2%were prepared and characterized by WDS and chemical methods.The results show that the three kinds of boron oxide content RCG powders can form dense coating after holding at 1300?,and the samples with higher content of boron oxide need lower temperature to form dense coating.