锆英砂包埋石墨法制备ZrC-SiC复合涂层

Preparation of ZrC-SiC Multi-coating on Graphite with ZrSiO_4 Powder via Pack Cementation

采用锆英砂包埋法,在石墨表面制备了ZrC-SiC复合涂层,利用X射线衍射仪、扫描电镜及能谱等分析手段,研究了涂层的形貌和结构,并通过热力学计算分析了复合涂层的形成过程.结果表明:复合涂层主要由ZrC和SiC相组成,局部存在SiC晶粒.由内向外,复合涂层形成了明显的双层结构,且主要由SiC富集内层和ZrC外层组成,热力学计算结果表明,包埋过程中各还原产物生成温度段的不同是复合涂层形成双层结构的主要原因,由于包埋过程中形成的中间相液Zr能流动封填涂层中存在的裂纹孔洞等缺陷,故反应后能制得致密的ZrC-SiC复合涂层.

To improve the oxidation resistance of graphite at high temperature,a dense ZrC-SiC multi-coating was prepared on graphite with ZrSiO_4 powder by pack cementation.The structure and morphology of the multi-coating were characterized by XRD,SEM and EDS analysis,and the formation of the coating was discussed with thermodynamics calculation.The results show that the coating has a double-layer structure,which consists of SiC-rich inner layer and ZrC out layer.Besides ZrC and SiC phases,SiC crystals are also formed in the coating.The formation of the double-layer structure is primarily attributed to the different generation temperatures of the reductive products in the system,and the dense structure of the multi-coating can be obtained due to the excellent flowing and filling ability of the liquid Zr formed in the preparation process.