摘要
分别用金属镍“扩散渗铝＋离子注Ｙ”与“Ｎｉ－Ｌａ２Ｏ３共沉积＋扩散渗铝”方法制备了Ｙ和Ｌａ２Ｏ３改性的β－ＮｉＡｌ涂层，与单纯的金属镍上的渗铝涂层相比，两种掺有稀土（ＲＥ）的β－ＮｉＡｌ涂层的氧化速率降低．ＳＥＭ的观察显示，１０００℃恒温氧化２４ｈ后，不含ＲＥ的涂层表面氧化膜已局部剥落，而含ＲＥ的涂层表面氧化膜不发生剥落，３种涂层的氧化层表面皆出现“晶须”或“刀片”状的氧化物．对含Ｙ涂层在氧化初期的不同阶段的表面进行ＳＥＭ观测，发现其上生长的氧化产物的形貌有明显的规律性变化．ＨＲＥＭ的结果显示，含Ｌａ２Ｏ３的涂层的α－Ａｌ２Ｏ３氧化物的部分小角晶界存在刃型位错的排列．对β－ＮｉＡｌ涂层的氧化物的生长机制及ＲＥ对其的影响作了详细探讨．
Y and La 2O 3 modified β NiAl coatings, developed respectively by aluminizing on nickel followed by yttrium implantation and electrodeposition of Ni La 2O 3 composite on nickel followed by aluminizing, displayed slower scaling rates after oxidation at 1273K for 24 h in comparision with that of β NiAl coating prepared by aluminizing on nickel. SEM observation revealed that whisker or blade like crystal oxides were grown on the scale surface of the three specimens, and that the spallation of scales occurred for RE free β NiAl coating, but not for Y or La 2O 3 containing β NiAl coating. SEM investigation also indicated that the oxide surface morphology of Y containing β NiAl coating varied regularly with time in the initial oxidation stage. HREM result showed that an array of edge dislocations was located along the low angle grain boundary of α Al 2O 3 oxide on La 2O 3 containing β NiAl coating. Accoding to the experimental results, the growth mechanism of scale on β NiAl coating as well as the effect of RE on the scale growth are discussed in detail.
出处
《腐蚀科学与防护技术》
CAS
CSCD
1997年第2期87-94,共8页
Corrosion Science and Protection Technology
基金
国家自然科学基金
国家高技术新材料领域专家委员会资助
