钼表面不同Al含量Mo(Si,Al)_2涂层的制备及氧化膜结构

Preparation and oxidation film structure of the Mo(Si,Al)_2 coatings containing different contents of Al on Mo

采用16Si-x Al-4NH4F-Bal.Al_2O_3(x=1,2,3,4,%,质量分数)渗剂经1200℃扩散共渗5 h在Mo表面制备了不同Al含量的Mo(Si,Al)_2涂层,分析了渗剂中Al含量对涂层组织及其氧化膜结构的影响。结果表明,不同渗剂所形成涂层均具有多层结构,涂层的外层均由Mo(Si,Al)_2相组成;渗剂Al含量为1和2%时,涂层中间层均为Mo_5(Si,Al)_3相,内层则分别为固溶有少量Al的Mo或Mo_3(Al,Si)相;渗剂Al含量为3和4%时,涂层中间层均由Mo5(Si,Al)_3和Mo_3Al_8相组成,内层则均为Mo_3(Al,Si)相。对含Al为1和4%的渗剂所制备的涂层在1250℃下氧化50 h,前者氧化膜厚度约为3μm,主要由SiO_2组成;后者氧化膜厚度约为10μm,上部由Al_2O_3和SiO_2的混合物组成,下部为Al_2O_3。

Mo（Si,Al）_2coatings with different Al content were prepared on Mo substrate surface by diffusion at 1200 ℃ for 5 h using 16 Six Al-4NH4F-Bal. Al_2O_3（x = 1,2,3,4%,mass fraction） as packs,and effects of Al content in the packs on microstructure and oxidation film structure of the coatings were studied. The results show that all the coatings have multi-layer structure,and the outer layer of the coatings is Mo（Si,Al）2phase. When the Al content is 1% and 2% in the packs,the middle layer of the coating is Mo_5（Si,Al）_3 phase,and the inner layer is a small amount of Al solid solution in Mo or Mo3（Al,Si） phase. When the Al content is 3% and 4% in the packs,the middle layer of the coatings is Mo_5（Si,Al）_3 and Mo_3Al_8 phases,and the inner layer is Mo3（Al,Si） phase. The coatings prepared in the packs containing 1% and 4% Al are oxidized at 1250 ℃ for 50 h,and a SiO_2 film with thickness of 3 μm forms on the former coating,while a 10 μm film forms on the latter coating which consists of Al_2O_3-SiO_2 in upper part and Al_2O_3 in lower part.