Carbon nitride deposition onto steel substrates by radio frequency plasma assisted pulsed laser deposition with substrate heating

Carbon nitride (CNx) films are promising candidates for tribological application due to its low friction coefficient. However, the adhesion strength of the film on steel substrate was poor at elevated temperature during deposition. In this study, CNx film was fabricated on bearing steel (SUJ2) and austenitic stainless steel (AISI304) substrates with radio frequency (RF) plasma assisted pulsed laser deposition in nitrogen gas atmosphere. Adhesion strength of the film on the steel substrates was improved by blasting or polishing of the substrate surface before deposition. Thick CNx film was deposited on the steel substrates by substrate heating and substrate pretreatment. The atomic composition ratio of N/C and the bonding ratio of sp3 / (sp2 + sp3) increased with substrate temperature. Maximum atomic composition ratio of N/C was 0.155 on SUJ2 substrate and 0.171 on AISI304 substrate at 40 W of RF power and 673 K of substrate temperature. The maximum adhesion strength of 14.8 MPa was obtained at blasted SUJ2 substrate. The maximum knoop hardness of 8.94 GPa and the lowest friction coefficient of 0.072 were obtained on SUJ2 substrate with polished #150 at 40 W of RF power and 673 K of substrate temperature.