钼基体表面硅化物涂层的包埋渗法制备工艺和机理研究  

Research on Process and Mechanism of Silicide Coating on Molybdenum Substrate by Pack Cementation

作　　者：何浩然 刘奇 薄新维 王小宇 王焱辉 姚志远 韩校宇 刘成超 HE Hao-ran;LIU Qi;BO Xin-wei;WANG Xiao-yu;WANG Yan-hui;YAO Zhi-yuan;HAN Xiao-yu;LIU Cheng-chao(Chongqing Materials Research Institute,Chongqing 400707,China;National Function Materials Research Institute,Chongqing 400707,China;School of Chemistry and Chemical Engineering,Chongqing University of Technology,Chongqing 400054,China)

机构地区：[1]重庆材料研究院有限公司,重庆400707 [2]国家仪表功能材料工程技术研究中心,重庆400707 [3]重庆理工大学化学化工学院,重庆400054

出　　处：《材料保护》2020年第2期99-104,共6页Materials Protection

基　　金：重庆市基础研究与前沿探索面上项目(cstc2019jcyj-msxm2574)资助。

摘　　要：目前,国内以NH4F为活化剂对钼基合金包埋渗硅,研究渗料组分对涂层沉积效率及作用机理的报道不多。为此,以NH4F为活化剂,研究并对比了不同活化剂含量下涂层的沉积效率,并通过热力学和动力学计算,分析了涂层沉积过程中活化剂的作用机理。结果表明:埋渗料配比按Si∶NH4F∶Al2O3=40∶10∶50于1000℃下埋渗5 h,涂层厚度可达53μm,高于相同工艺下,以NH4Cl、NaF为活化剂的涂层沉积厚度。当埋渗硅含量充足时,包埋渗硅涂层具有2层结构,外层为MoSi2相,扩散层为Mo5Si3相。通过热力学分析知Mo5Si3较Mo3Si更为稳定,贫硅过渡区更易生成Mo5Si3相。包埋渗硅涂层的沉积受反应扩散过程控制。相同工艺条件下拟合的速率方程中,NH4F为活化剂所得速率常数值最大为18.5。该活化剂下埋渗的涂层,SiF2的平衡分压对涂层生长的气相扩散过程起控制作用,且SiF2的平衡分压均高于以NH4Cl、NaF为活化剂下SiX2(X=Cl,F)的平衡分压。Using NH4F as activator,the deposition efficiency of silicide coating on different activator content was researched and compared,and the mechanism of activator during deposition by thermodynamic and kinetic calculations was analyzed.Results showed that the coating thickness could reach 53μm at 1000℃for 5 h in the proportion of Si∶NH4F:Al2O3=40∶10∶50,which was higher than the coating deposition thickness with NH4Cl and Na F as activators under the same process.When the content of packing silicon was sufficient,the packing silicide coating contained two layers:the outer layer was MoSi2 phase,and the inner layer was Mo5Si3 phase.Thermodynamic analysis showed that Mo5Si3 was more stable than Mo3Si,and it was easier to generate Mo5Si3 phase in the poor silicon transition region.Furthermore,the deposition of packing silicide coating was controlled by reaction-diffusion process.In the rate equation fitted under the same process condition,the rate constant using NH4F as activator was 18.5,which was higher than those using other two activator(Na F,NH4Cl).When NH4F was used as activator,the equilibrium partial pressure of SiF2 controlled the gas phase diffusion process during coating growth.Meanwhile,the equilibrium partial pressure of SiF2 was higher than that of SiX2(X=F,Cl)with Na F or NH4Cl as activator.

关 键 词：钼基合金 硅化物涂层 包埋渗法 渗料配比 机理研究 

分 类 号：TG146.4[一般工业技术—材料科学与工程]