铜基体上渗铝层的高温抗氧化性能和组织变化

摘要

以铜为基体，采用电镀镍和浆料包渗铝法，在800°C渗铝12 h制备出组织为Ni2Al3的单相渗层。采用SEM、XRD和光学显微镜，研究在1000°C下空气中氧化25~250 h，Ni2Al3渗层的高温抗氧化性能与组织转变行为。结果表明：Ni2Al3渗层在1000°C氧化250 h后，氧化增重分别为纯铜和镍镀层的1/15和1/2。氧化时间在25 h内时，渗层表面仍有Ni2Al3相；氧化50 h后，出现NiAl相；当氧化时间增加到100 h时，Ni2Al3相完全转变为NiAl相。当氧化到250 h时，渗层仍具有良好的抗高温氧化性能。%The outermost coating with single phase Ni2Al3 was obtained on copper surface by electrodepositing nickel followed by slurry pack aluminizing at 800 °C for 12 h. The oxidation resistance and microstructure of the coating oxidized in ambient air at 1000 °C for 25−250 h were investigated using SEM, X-ray diffraction and optical microscope methods. The results show that the copper with single phase Ni2Al3 coating possesses the best high temperature oxidation resistance, and the mass gain of the coating is 1/15 that of pure copper and 1/2 that of nickel coating, respectively. The specimen surface after being oxidized for 25 h still comprises Ni2Al3 phase. However, when the time of oxidizing treatment increases to 50 h, the NiAl phase is formed. It is also found that the Ni2Al3 phase completely turns into NiAl phase after oxidizing treatment for 100 h and above. The NiAl coating shows excellent high temperature oxidation resistance when oxidation time is 250 h.