Study of the Effect of Nitrogen on Corrosion, Wear resistance and Adhesion Properties of DLC Films Deposited on AISI 321H

Abstract

The deposition of DLC films on 321H stainless steel aims at attributing properties such as high wear resistance and low friction coefficient to the substrate material. Nitrogen added to DLC can improve the film adhesion to metal substrates, but the investigation of its effect on corrosion resistance, an important property for stainless steels, is lacking. The DLC film was deposited by plasma-enhanced chemical vapor deposition (PECVD) using a pulsed-DC power supply with a gas mixture of Ar and CH₄, and to the DLC(N) film deposition was used CH₄ and N₂ varying the percentage of nitrogen from 10 to 50% in the treatment. DLC films improved both the wear and corrosion resistance of 321H stainless steel. The results show that the 10, 20 and 30% of N₂ supply during the deposition increased the adhesion of the film on the substrate, enhancing the wear resistance of the treated material. The addition of 40 and 50% of N₂ during the deposition, however, impaired the corrosion resistance compared with the substrate. An improvement of adhesion, wear and corrosion resistance were observed for 30% N₂ condition. Thus, the incorporation of suitable concentration of nitrogen modifies the features of the DLC film, obtaining a good combination of high wear resistance and corrosion protection due to a combination of structure, high thickness, and high adhesion of the film to 321H stainless steel.

Keywords:
micro-abrasive wear; DLC; corrosion potential; nitrogen