Study on fretting wear behavior of laser treated coatings by X-ray imaging

Abstract

The probability of encountering fretting in machines and engineering structures is extremely high, and it is well known that aluminum alloys have poor fretting wear resistance. In this investigation, effect of laser surface alloying of Ni, Cr on the fretting resistance of 6061 aluminum alloys under unlubricated conditions was studied. The fretting wear performance of the laser treated alloys was characterized by evaluating the wear volume loss, the coefficient of friction and fretting mechanisms. It was found that the fretting wear resistance of 6061 aluminum alloy was improved by a factor of 3 after laser alloying while the coefficient of friction was decreased. In situ observation of fretting wear was performed by means of X-ray imaging (real time radiography) in this investigation. The obtained X-ray images and SEM post-observation of the fretting scar indicated that the fretting wear process of laser treated specimens was a combination of adhesive, abrasive, oxidation and delamination wear. The mechanisms during the running-in period are adhesive and abrasive wear. During prolonged running, delamination and oxidation were the main wear mechanisms for both laser treated and untreated specimen.