K4104镍基高温合金Al-Si涂层高温氧化过程中的元素扩散分析

采用无机盐料浆法在K4104镍基高温合金表面制备Al-Si涂层。依据GB/T13303-91《钢的抗氧化性能测定方法》标准,采用静态增重法对有涂层试样和无涂层试样进行了1000℃×200h抗高温氧化性能试验,并绘制了氧化动力学曲线。用带能谱扫描电镜对氧化膜的表面形貌和截面组织进行分析,研究有无涂层试样在高温氧化过程中的元素扩散。结果表明:Al-Si涂层和基体合金之间在高温氧化过程中的互扩散形成了厚度为120~140um的渗层。随着氧化时间的延长,外层铝含量逐渐降低,但仍能保持稳定的β-NiAl相。Si在扩散作用下形成内高外低的分布形式,形成的Cr3Si和富Si的M6C相有利于阻止涂层和基体元素之间的互扩散,降低化合物层的形成速度,体现了Al-Si涂层良好的抗高温氧化能力。

Elements Diffusion of Al-Si Coating on Nickel-Base Superalloy K4104 in High Temperature Oxidation Process

Al-Si binary diffused coatings were prepared on nickel-base superalloy K4104 by the slurry process.According to GB/T13303-91,the high temperature oxidation experiment at 1000℃ of specimens with coating and without coating was carried out with static mass gain method.Surface and section morphology and content of the oxide layer were studied by means of SEM/EDX,and the elements diffusion for the samples in the high temperature oxidation was analyzed.The results indicated that diffusion between Al-Si coatings and the superalloy substrate caused a 120~140μm thick coating structure.In the processing of oxidation,the content of Al in the surface layer decreased,but steady β-NiAl phase in this layer could be kept.As the diffusion continued,there was more Si in the outer and inner layer,the Cr3Si and M6C which contain rich Si were helpful for preventing the diffusion between the coating and the substrate,and reducing the rate of compound formation.It indicates that Al-Si coating had active effect on high temperature oxidation resistance.