摘要
解决难熔高熵合金在高温下的抗氧化问题是其应用于工程的前提,在难熔金属表面制备抗氧化涂层是提高其抗氧化性能的有效途径。采用料浆熔烧法在MoNbTaTiW难熔高熵合金表面制备复杂硅化物抗氧化涂层(Si-20Cr-20Fe),利用扫描电镜(SEM)、能谱仪(EDS)和X射线衍射(XRD)等研究原始硅化物涂层及其在1300℃氧化后的显微结构、物相和成分,探讨Si,Fe,Cr在涂层中的扩散规律和涂层的抗氧化机理。结果显示:熔烧后的原始硅化物涂层由金属与硅反应生成的二硅化物、5/3硅化物和三元硅化物Cr_(4)Nb_(2)Si_(5)组成,硅化物涂层与基体之间形成了良好的扩散反应界面。1300℃氧化后,Si,Fe,Cr 3种元素向基体扩散,扩散反应界面向基体方向移动,涂层厚度增加,扩散反应界面的结构与成分与原始复杂硅化物涂层的无显著差别。氧化后涂层表面形成了由CrNbO_(4),SiO_(2),WO_(3)和Fe_(2)SiO_(4)组成的无裂纹致密氧化物层,阻止了氧向基体内的进一步扩散。Si,Fe,Cr在MoNbTaTiW难熔高熵合金中具有不同扩散速度,Si的扩散速度最快,Fe次之,Cr最慢。Fe和Cr在低硅含量的扩散层和硅化层中出现富集现象。料浆熔烧法制备的复杂硅化物涂层在高温下为MoNbTaTiW难熔高熵合金提供了抗氧化防护。
Solving the oxidation resistance problem of refractory high-entropy alloy at high temperature is the premise of application in engineering.The preparation of anti-oxidation coating on the surface of refractory metal is an effective way to improve its oxidation resistance.A complex silicide anti-oxidation coating(Si-20 Cr-20 Fe)was prepared on the surface of MoNbTaTiW refractory high-entropy alloy by slurry fusion sintering method.The microstructure,phase and composition of the initial silicide coating and the coating after oxidation at 1300℃were studied by SEM,EDS and XRD.The diffusion law of Si,Fe and Cr in the coating and the anti-oxidant mechanism of the coating were explored.Results showed that the initial silicide coating after melting was composed of disilicide,5/3 silicide and ternary silicide Cr_(4)Nb_(2)Si_(5) formed by the reaction between metal and silicon.A good diffusion reaction interface was formed between the silicide coating and the substrate.After oxidation at 1300℃,Si,Fe and Cr diffused to the substrate,and the diffusion reaction interface layer moved to the substrate,consequently the coating thickness was increased.The microstructure and composition of the diffusion reaction interface layer were almost the same as the diffusion layer of the complex initial silicide coating.After oxidation,a crack-free,dense oxide layer was formed on the surface ofthe coating.The layer was composed of CrNbO_(4),SiO_(2),WO_(3) and Fe_(2)SiO_(4),and it could prevent the further diffusion of oxygen to the inside ofsubstrate.Si,Fe and Cr had different diffusion rates in MoNbTaTiW refractory high-entropy alloy.The diffusion rate of Si was the fastest,Fewas the second,and Cr was the slowest.Therefore,Fe and Cr were enriched in the low silicon content diffusion layer and silicide layer.Thecomplex silicide coating prepared by slurry fusion sintering could provide good anti-oxidation protection for MoNbTaTiW refractory high-entropyalloy at high temperatures.
作者
韩杰胜
苏博
张爱军
孟军虎
吴有智
HAN Jie-sheng;SU Bo;ZHANG Ai-jun;MENG Jun-hu;WU You-zhi(School of Materials Science and Engineering,Lanzhou University of Technology,Lanzhou 730050,China;State Key Laboratory of Solid Lubrication,Lanzhou Institute of Chemical Physics,Chinese Academy of Sciences,Lanzhou 730000,China)
出处
《材料保护》
CAS
CSCD
2022年第2期1-8,59,共9页
Materials Protection
基金
甘肃省自然科学基金项目(20JR5RA560)资助。
关键词
硅化物涂层
难熔高熵合金
料浆熔烧
抗氧化涂层
silicide coating
refractory high-entropy alloy
slurry fusion sintering
anti-oxidation coating
