Investigation of Nano Composite Coating on Aluminum Alloys Treated by Plasma Transferred Arc

Abstract

Using a combination of high speed jet electrodeposition and plasma transferred arc (PTA) quenching, a nano-TiN/Ni composite coating on 7005 aluminium alloy can be produced. The microstructure, microhardness, friction coefficient and corrosion potential Ecorr of PTA treated specimens were investigated. The results showed that a rapidly solidified microstructure consisting of the uniformly distributed TiN phase and fine Al3Ni2 intermetallic phase was in PTA treated specimens. The results also showed that the composite coating PTA treated has an average microhardness of approximately 800 HV. The friction coefficient of PTA treated specimens (oscillated around 0.25) is considerably lower than that of TiN/Ni composite coating (oscillated around 0.35). The PTA treated specimen had the lowest corrosion current density Icorr as well as the highest corrosion potential Ecorr and showed an improved corrosion resistance compared to 7005 aluminium alloy as well as TiN/Ni composite coating.