Effects of CeO2 Addition on Microstructure and High Temperature Oxidation Resistance of Ti-Al Coating

Using slurry pack cementation mixture with TiO2 as titanizing source, pure Al powder as reducer, NH4Cl as activator, Al2O3 as inert additive and albumen (egg white) as cohesive agent, electroplated specimens with a layer of electroplating nickel originally deposited on copper were titanized to prepare Ti-Al coating. The effect of CeO2 oxides on the microstructures and high temperature oxidation resistance of Ti-Al coating were studied. The results show that the phases of the coating are transformed from Ni-Ti to Ni-Al intermetallics, and the process of slurry pack cementation are also changed from the titanizing-base dual process to the aluminizing process after adding CeO2 oxides. The oxidation mass gain of Ti-Al coating is decreased from 1/10 of that of pure copper to 1/28. The oxide is primarily composed of TiO2, Al2O3 and a small amount of NiO. The oxide layer is dense without cracks and pores, which improves the high temperature oxidation resistance.