纯钼表面包埋Si-B共渗涂层的显微组织及低温氧化行为

Microstructure and low temperature oxidation of pack Si-B co-deposition coating on pure Mo

在纯钼表面进行包埋Si-B共渗,研究B改性MoSi2涂层的结构及其在600℃下的氧化行为。利用XRD,EDS,WDS分析涂层的相组成和结构,并结合热力学计算分析涂层的组织形成。结果表明:采用16Si-4B-4NaF-76Al2O3渗剂在1100~1400℃下可制备Si-B共渗涂层,涂层由外向内可分为五层:最外层MoSi2,次外层MoSi2+MoB,第三层Mo5Si3,第四层MoB和最内层Mo2B;涂层主体为MoSi2,渗入的B在与基体反应形成Mo-B化合物层的同时,还在MoSi2中形成MoB相;涂层的生长以Si,B原子向内扩散为主;在600℃氧化时涂层中的B向表面扩散并氧化生成B2O3。

B-modified MoSi2 coatings on pure Mo surface were prepared by pack Si-B co-deposition process.The phase structure and composition of the coatings were studied by means of XRD,EDS and WDS techniques.Coating formation mechanism was investigated based on thermodynamics calculation.The results show that the Si-B co-deposition coatings prepared at 1100 ~ 1400 ℃ in the pack 16Si-4B-4NaF-76Al2O3 have a 5-layer structure.From surface to substrate,the coating can be divided into the MoSi2 out layer,the MoSi2+MoB second layer,the Mo5Si3 third layer,the MoB fourth layer and the Mo2 B inner layer.The growth of the coating is dominated by the inward diffusion of Si and B.The deposition of Si mainly forms MoSi2 phase,and the inward diffusing B either diffuses into the substrate to form Mo-B composite layers or develops MoB dispersions in MoSi2.Oxidation behavior of the Si-B co-deposition coating at 600 ℃reveals that B atoms can diffuse outward to the coating surface and oxidize to B2O3.