Effects of Micro-Arc Oxidation of Ti6Al4V Alloy on Adhesion Property to Electroless Ni-P-ZrO2 Composite Platings and Their Wear Resistance

An electroless Ni-P-ZrO2 composite plating was prepared on the porous surface of the Ti6Al4V alloy pretreated by micro-arc oxidation (MAO) for 15, 30, 60 and 90 min, respectively. The effects of the microstructures of the MAO coatings on the adhesion properties of the electroless Ni-P-ZrO2 plating and their tribological behavior were examined by SEM/EDS, scratch and thermal shocking tests, a microhardness tester and a ball-on-disc wear testing machine. The results indicate that the adhesion property of the Ni-P-ZrO2 composite plating of the MAO coatings is distinctively improved with the increase of MAO processing time. The reason is attributed to the larger porosity and the enhanced mechanical interlocking effect. Compared with the Ti6Al4V alloy, the microhardness and the wear resistance under drying sliding condition of the Ti6Al4V alloy are greatly improved by the duplex treatments. The wear mechanism of the Ti6Al4V alloy is severe adhesion and abrasion wear, while the electroless Ni-P-ZrO2 composite plating shows microabrasion wear.