SiC陶瓷表面Mo-Ni-Si金属化及其与Ag的润湿性研究

采用真空熔烧工艺在SiC陶瓷表面制备了三种化学成分的Mo-Ni-Si金属化涂层,研究涂层的相组成和涂层/SiC陶瓷界面的微结构。通过座滴法实验考察纯Ag在SiC陶瓷涂层上的润湿与铺展特性,分析和讨论了Ag/金属化SiC陶瓷体系的界面行为。实验结果表明,该金属化涂层主要由Mo₅Si₃, MoSi₂, Ni₂Si, NiSi₂ 和MoNiSi组成,同时随着涂层中Mo的摩尔比由20%增加至40%,位于涂层表面的具有四方结构的MoSi₂晶粒逐渐消失。Ag对Mo20-Ni32-Si48、Mo30-Ni28-Si42、Mo40-Ni24-Si36金属化SiC陶瓷在1000 oC保温30分钟后对应的最终接触角分别为45o, 79o 和 85o,该结果与Ag滴和三种Mo-Ni-Si涂层之间的相互作用密切相关。同时在润湿试验前后,在Mo-Ni-Si涂层/SiC衬底界面没有发现明显的反应层。

Surface Metallization of SiC Ceramic by Mo-Ni-Si Coatings for improving its wettability by molten Ag

Three Mo-Ni-Si metallizing coatings with various chemical compositions were deposited on SiC ceramic substrates by vacuum fusion sintering process, and the phase compositions of the coatings and their interface microstructure were analyzed. The wetting and spreading of molten Ag on the coated SiC ceramic substrates were investigated by the sessile drop technique, and the interfacial behavior of the Ag/coated SiC systems was analyzed and discussed. The experimental results showed that the coatings were mainly composed of Mo₅Si₃, MoSi₂, Ni₂Si, NiSi₂ and MoNiSi. The tetragonal MoSi₂ grains located on the coating surface disappeared with the concentration of Mo increasing from 20 at.% to 40 at.%. The final contact angles of Ag/coated SiC systems at 1000 oC for holding 30 min were 45o, 79o and 85o for Mo20-Ni32-Si48, Mo30-Ni28-Si42 and Mo40-Ni24-Si36, respectively. This result can be closely related to the interactions between the Ag drop and the microstructure of the three Mo-Ni-Si coatings. No visible reaction layers were observed at all the coating/substrate interfaces before and after the wetting tests.