通过对助烧机理的研究发现：AlN原料中并不存在氧化铝相，CaF2和YF

The study on the mechanism of sintering aids found that there is no alumina phase in AlN raw materials, and CaF2 and YF3 do not react with AlN. It generates liquid phase at high temperature to promote the densification of complex ceramics and the growth of AlN and h-BN grains. . <br>Compared with CaF2 as a sintering aid, YF3 as a sintering aid for the preparation of h-BN/AlN composite ceramics has better performance. <br>This is because YF3 is a fluoride with a lower melting point than CaF2, and as a sintering aid, it is easier to promote ceramic densification. <br>In addition, under the same sintering conditions, the weight loss rate of YF3 is higher than that of CaF2, which makes the content of grain boundary phase inside the multiphase ceramics further reduce, thereby improving the thermal conductivity and dielectric properties of the multiphase ceramics.

Through the study of the mechanism of heating, it is found that there is no alumina phase in AlN raw material, CaF2 and YF3 do not react with AlN, it promotes the complex ceramic density and the growth of AlN, h-BN grains by producing liquid phases at high temperatures.<br>Compared with CaF2 as a sintering additive, YF3 prepares h-BN/AlN polyphase ceramics for sintering additives with better performance.<br>This is due to the fact that YF3 is a fluoride with a lower melting point than CaF2, which is more likely to promote ceramic density as an sintering additive.<br>In addition, under the same sintering conditions, the weightlessness rate of YF3 is higher than CaF2, which further reduces the crystal boundary phase content inside the complex ceramic, thus improving the thermal and dielectric properties of the complex ceramic.

It is found that there is no alumina phase in AlN, CaF2 and yf3 do not react with AlN. It can promote the densification of composite ceramics and the growth of AlN and h-BN grains by forming liquid phase at high temperature.<br>Compared with CaF2, yf3 has better properties in preparing h-BN / AlN composite ceramics.<br>This is due to the fact that yf3 is a fluoride with lower melting point compared with CaF2, and it is easier to promote densification of ceramics with yf3 as sintering aid.<br>In addition, the weight loss rate of yf3 is higher than that of CaF2 under the same sintering conditions, which further reduces the content of grain boundary phase in the composite ceramics, thus improving the thermal and dielectric properties of the composite ceramics.<br>