Effect of Cr diffused layer formed by AIH-FPP on adhesion strength of DLC films

In this study, in order to improve the adhesion strength of diamond-like carbon (DLC) films, medium carbon steel specimens were treated by using an atmospheric-controlled induction heating fine particle peening(AIH-FPP) with Cr particles that have high affinity for DLC films. The AIH-FPP treated specimens were characterized using optical microscope, scanning electron microscope and energy dispersive X-ray spectrometer. It was found that a diffused layer of Cr was formed on the specimen surface that was treated with AIH-FPP. The modified layer was then coated with DLC films, and in order to investigate the adhesion strength of DLC films on the surface modified substrates, reciprocating wear and indentation tests were performed. It was revealed that a Cr diffused layer formed by AIH-FPP treatment improved the adhesion strength of DLC films against sliding loads and large plastic deformations. In addition, the adhesion strength of DLC films was improved by increasing the thickness of a Cr diffused layer and superior friction characteristics were maintained for a long time. These results suggest that a Cr diffused layer induced by AIH-FPP treatment is an effective method for improving the adhesion strength of DLC films.