Study On The Preparation And Corrosion Resistance Of Micro-arc Oxidation Coatings Of Zr702Alloy

Zr702alloy are always attractive materials for different structural applications in nuclearindustry and chemical industry. However, the extensive applications of Zr702alloy arelimited by their poor corrosion resistance in special service environment. Thus, in this paper,the ceramic layer on the surface of Zr702alloy was performed by micro-arc oxidationtechnology, the corrosion resistant and microstructure of the ceramic layer with differentprocessing parameters such as electrolyte and electrical parameters were investigated, and thegrowth mechanism and corrosion resistance characteristic were also discussed. The resultsshow that the ceramic layers were constructed in all electrolytes in the experiment. The Zr702alloy after micro-arc oxidation in phosphate electrolyte exhibited excellent corrosionresistance, and this considered to be associated with the microstructure of the layer. It is foundthat the layer after micro-arc oxidation in phosphate electrolyte is consisted of smooth andcompact m-ZrO₂and t-ZrO₂, which has less corrosion channels and more t-ZrO₂comparedwith another layer treatment in silicate and zircon salt electrolyte, this is the main reason forthe improving corrosion resistance. Moreover, electricity parameter optimization results showthat ceramic layer has good corrosion resistance after formed by voltage of460V in silicateelectrolyte,440V in zircon salt electrolyte and480V in phosphate electrolyte, respectively.The Zr702alloy after micro-arc oxidation under voltage of480V in phosphate electrolyteexhibited best corrosion resistance in all samples.