STUDY ON FRETTING WEAR BEHAVIOR OF LASER TREATED COATINGS BY X-RAY-IMAGING

The probability of encountering fretting in machines and engineering s tructures 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 al uminum alloys under unlubricated conditions was studied. The fretting wear performance of the laser treated alloys was characterized by eval uating the wear volume loss, the coefficient of friction and fretting mechanisms. It was found that the fretting wear resistance of 6061 alu minum alloy was improved by a factor of 3 after laser alloying while t he coefficient of friction was decreased. In situ observation of frett ing wear was performed by means of X-ray imaging (real time radiograph y) in this investigation. The obtained X-ray images and SEM post-obser vation of the fretting scar indicated that the fretting wear process o f laser treated specimens was a combination of adhesive, abrasive, oxi dation and delamination wear. The mechanisms during the running-in per iod are adhesive and abrasive wear. During prolonged running, delamina tion and oxidation were the main wear mechanisms for both laser treate d and untreated specimen. (C) 1998 Elsevier Science S.A. All rights re served.