激光熔覆Y改性Mo-Si-B涂层的抗高温氧化性能研究  

High Temperature Oxidation Resistance of Y-modified Mo-Si-B Coating Prepared by Laser Cladding

作　　者：周傲寒 邵蔚 ZHOU Aohan;SHAO Wei(School of Materials Science and Engineering,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]北京工业大学材料科学与工程学院,北京100124

出　　处：《中国钨业》2024年第3期74-80,共7页China Tungsten Industry

基　　金：高能束流加工技术重点实验室稳定支持项目;北京市教委科技计划一般项目(KM202110005007);国家自然科学基金(25001014)。

摘　　要：为进一步改善涂层的显微组织,提高涂层的抗高温氧化性能,本文利用激光熔覆工艺在Nb-Si基合金表面制备含Y和含Y_(2)O_(3)的Mo-Si-B涂层,探索Y和Y_(2)O_(3)对Mo-Si-B涂层结构和抗高温氧化性能的影响。结果表明,添加Y和Y_(2)O_(3)的Mo-Si-B涂层主要由t-MoSi_(2)相、h-MoSi_(2)相、Mo5Si3相和少量MoB_(2)相组成。添加Y能促进Mo-Si-B涂层中元素的扩散,使涂层中的化学组成、组织结构分布更加均匀,MoSi_(2)相尺寸减小,共晶组织增多并且细化。而添加Y_(2)O_(3)的Mo-Si-B涂层中含有大量的Mo_(5)Si_(3)相,基体对涂层的稀释作用较大。在1250℃空气环境下氧化60 h后观察涂层的高温氧化行为,发现添加Y元素提高了Mo-Si-B涂层的高温抗氧化性能,而添加Y_(2)O_(3)后涂层的抗氧化能力显著下降。添加Y的Mo-Si-B涂层表面快速形成了连续且致密的氧化膜,这是因为Y元素的添加细化了涂层的晶粒,使保护性元素可以更快速地扩散到涂层表面,与氧发生反应形成保护性的硅硼酸盐氧化层,有效促进Mo-Si-B涂层表面氧化膜的形成,提高Mo-Si-B涂层的抗高温氧化性能;添加Y_(2)O_(3)的Mo-Si-B涂层抗氧化相为Mo_(5)Si_(3)相,Si含量降低,因此在氧化过程中生成了大量含Nb的尖晶石型氧化物,破坏硅硼玻璃相氧化膜的连续性,导致含Y_(2)O_(3)的Mo-Si-B涂层抗高温氧化性能变差。As an important ultra-high temperature structural material,Nb-Si based alloys boast advantages of high melting point,low density,and excellent high-temperature performance,making them promising candidates for aerospace sector.However,the poor high-temperature oxidation resistance significantly hinders the development of Nb-Si based alloys.Silicide coatings can effectively enhance the high-temperature oxidation resistance of Nb-Si based alloys.Y and Y_(2)O_(3)modified Mo-Si-B coatings were prepared on the surface of Nb-Si based alloys with the laser cladding technique.The Y/Y_(2)O_(3)modified Mo-Si-B coatings mainly consist of t-MoSi_(2),h-MoSi_(2),Mo_(5)Si_(3),and a small amount of MoB_(2).The addition of Y promotes the diffusion of elements within the Mo-Si-B coating,resulting in a more uniform distribution of chemical composition and microstructure,a reduction in the size of MoSi_(2)phase,and an increase in the proportion of eutectic structure.In contrast,the Y_(2)O_(3)modified Mo-Si-B coating contains a significant amount of Mo_(5)Si_(3)phase and exhibits considerable dilution effects from the substrate.After oxidation at 1250℃for 60 hours,a continuous and dense oxide layer is formed on the surface of the Mo-Si-B coating,predominantly composed of borosilicate.The addition of Y enhances the formation of oxide layer on Mo-Si-B coating surface and significantly improves its oxidation resistance at high temperatures.However,the Y_(2)O_(3)modified Mo-Si-B coating tends to generate non-protective metal oxides during the oxidation process.Compromising the continuity of borosilicate glass phase,it ultimately generate decreased high-temperature oxidation resistance for the coating containing Y_(2)O_(3).

关 键 词：激光熔覆 Nb-Si合金 Mo-Si-B涂层 Y Y_(2)O_(3) 抗高温氧化性能 

分 类 号：TG178[金属学及工艺—金属表面处理]