高温合金低压气相沉积渗铝工艺研究

Low-Pressure Gas Deposition Aluminizing Process for K17 Superalloy

研究了活性元素Pd对高温合金K17表面上低压气相沉积(LPGD)渗铝工艺的影响。结果表明,在合金表面预沉积Pd-20%Ni合金后,在950℃和1050℃渗铝制备铝化物涂层,与未经过电镀处理的样品相比,其渗铝速度得到了提高,形成铝化物涂层的动力学在950℃时符合抛物线规律,而在1050℃时则近似线性关系。“S”渗铝量对总渗铝量的比例不容忽视,在950℃时为33%左右,和渗铝工艺有关,与样品预处理状态无关,提高渗铝温度,“S”渗铝比例提高。Pd元素加快了元素的扩散速度,促进了涂层的生长。

The low-pressure gas deposition aluminizing process for K17 superalloy was investigated. It was found that the introduction of an electroplated Pd-20%(mass fraction)Ni alloy coating on the superalloy surface contributed to speed its aluminizing rate as compared with the one without the electroplated coating. In terms of the kinetics for the aluminide coating to form, a parabolic relation was observed at 950 ℃, while a nearly linear relation was observed at 1 050 ℃. Moreover, it could be imperative to notice the “S” aluminizing content in proportion to the total aluminizing content. Namely, the proportion of “S” aluminizing content increased with increasing aluminizing temperature and was only related to the aluminizing process but independent on the pre-treatment state of the sample. In addition, Pd in the electroplated layer helped to enhance the diffusion of Al and hence speed the growth rate of the aluminide coating.