摘要
航空发动机涡轮叶片在使用时需加以涂层防护,以提高基体合金的抗高温氧化性能。本研究采用料浆渗铝的制备工艺,以CaCl_(2)作为活化剂,在NiCrW基高温合金表面制备Al-Si涂层。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)及能谱仪(EDS)对涂层试样的表面和截面进行分析。结果表明,聚乙烯醇水溶液可作为料浆法制备渗铝/铝硅涂层的有效黏结剂;高温扩散的温度和时间显著影响渗铝涂层的厚度。渗剂成分为5%Si+30%Al(质量分数),制备得到的共渗涂层由外而内依次为富Al层、NiAl层和含Si过渡层三部分,涂层致密无明显缺陷,厚度约为57μm。10%Si+25%Al、15%Si+20%Al与20%Si+15%Al共渗涂层由外而内分为富Al层、富Ni层和含Si过渡层三层。Si元素主要以含Si的沉积相形式存在于含Si过渡层中,少量沉积于外层。而Si的少量添加能明显影响Al、Ni元素的扩散过程,从而减小涂层厚度,并由单一NiAl相向富Al、富Ni的镍铝相转变。
Aero-engine turbine blades should be coated for protection to improve the high temperature oxidation resistance of the alloy substrate.In this study,an Al-Si coating was prepared on the surface of NiCrW-based superalloy with CaCl2 as the activator by slurry method.X-ray diffractometer(XRD),scanning electron microscope(SEM)and energy spectrometer(EDS)were used to analyze the surface and cross-section of the coating.The results show that the aqueous solution of polyvinyl alcohol can be used as an effective binder for preparing aluminized/aluminized-silicon coatings by slurry method,and the temperature and the heating time of high-temperature diffusion significantly affect the thickness of the aluminized coating.When the composition of binder is 5%Si+30%Al(mass fraction),the coating is composed of aluminum-rich layer,NiAl layer and silicon-containing transition layer from the outside to the inside.The NiAl coating is dense and has no obvious defects,and the thickness is about 57μm.While the compositions of binder are 10%Si+25%Al,15%Si+20%Al and 20%Si+15%Al,the coatings are divided into three layers:Aluminum-rich layer,nickel-rich layer and silicon-containing transition layer from the outside to the inside.Silicon is mainly exist in the silicon-containing transition layer in the form of silicon-containing deposition phases,and a small amount of silicon is deposited on the outer layer.The addition of a small amount of Si can significantly affect the diffusion process of aluminum and nickel elements,and reduce the thickness of the coating,and transform the phase of the coating from a single NiAl phase to an aluminum-rich phase,nickel-rich phase.
作者
高杉
邹俭鹏
GAO Shan;ZOU Jianpeng(State Key Laboratory of Powder Metallurgy,Central South University,Changsha 410083,China)
出处
《粉末冶金材料科学与工程》
EI
2021年第2期155-165,共11页
Materials Science and Engineering of Powder Metallurgy
基金
湖南省自然科学基金资助项目(2018JJ2524)。
关键词
镍基高温合金
料浆法
渗铝涂层
铝硅共渗
微观结构
nickel-based superalloy
slurry method
aluminized coating
aluminum-silicon co-permeation
microstructure
