Influence of Pt particles on the porosity of Al2O3 coating prepared by cathode plasma electrolytic deposition

Porous Al2O3 and Al2O3-Pt coatings were successfully prepared on the Ni-based alloy by cathode plasma electrolytic deposition. It is found that the porosity of coatings can be reduced obviously by Pt particles co-deposited with Al2O3. This phenomenon can be attributed to that the mechanism of plasma discharge is changed in such CPED. As the Pt particles are dispersed in the Al2O3 coating, the electron avalanche is difficult to occur. So, the breakdown takes place in the Al2O3-Pt coating difficultly, the destructive effect of the breakdown will therefore be decreased, and the porosity of Al2O3 coating can be reduced which has been verified by the results of surface morphologies of the coatings.