复杂型腔空心叶片气相渗铝工程化应用研究

Research on Engineering Application for Vapor Aluminizing Process of Hollow Blade

对航空发动机复杂型腔空心叶片气相渗铝工艺、组织结构进行了研究,探讨了气相渗铝工艺的原理和机制。结果表明,采用含Al 30%（质量百分比）的渗铝剂可实现空心叶片表面和内腔的同时渗铝,渗层深度可控、均匀性好,随渗铝保温时间的延长而递增,叶片表面渗铝层深度为20~60μm,内腔为5~20μm,渗铝层组织主要分为两个特征区,厚度比约为1：1。外层铝为32%~36%（质量百分比）左右,内层铝约为11%~17%（质量百分比）;外层主要由β-Ni Al相,内层可能由β相,或β＋γ＇相,或γ＇相组成。叶片经980℃、4h气相渗铝后,组织良好、性能优良,通过了航空发动机1000h持久试车考核,工程化应用前景广阔。

Vapor aluminizing process and microstructure of hollow blade in aero-engine has been researched. The mechanism of the coating has been analyzed. The results show that the depth of the surface coating is 20~60ktm, by 30% Al aluminizing powder. And the internal coating of turbine blade is 5-20μm. The depth increases with the extension of the alu- minized time. The coating mainly comprises two layers with the same depth. The surface layer is 32%-36% Al, with β-NiAl phase, And the inner layer is 11%~17% Al, with β-NiAl phase, or β＋γ′ phase, or γ′ phase. There are needles which are ar- ranged disorderly and a small amount of foreign substance in the inner layer. The main reason of high-Al in the coating is the rust of crucible. The crucible has been forced aluminized with high temperature and long time. The blade coating has good microstructure and mechanical properties after been vapor aluminized at 980 ℃ for 4h, through the assessment of the aero-engine 1000h lasting. The prospect of engineering application for vapor aluminizing process of hollow blade is very good.