Development of diamond-like carbon (DLC) coating compatible surface by Fine Particle Bombardment (FPB)

To improve adhesion of DLC coatings, Fine Particle Bombardment (FPB) treatment using Cr based shot particles was performed. After the FPB treatment, DLC coating process was generated on the Chromium-molybdenum steel. The FPB treatment distributes diffused Cr elements onto the treated surface, creating a Cr-rich layer. The FPB treatment increases the surface hardness and roughness which also affect the adhesion of DLC coatings. Wear test was conducted to compare the tribological properties of the DLC coated FPB treated steels and that of the DLC coated non FPB treated ones. The DLC coated surface, after FPB treatment, kept low friction coefficient, while the DLC coated non FPB treated ones showed a sudden increase due to the delamination of DLC layer. These results imply that delamination of the DLC coating was suppressed by the Cr-rich surface layer created by the previous FPB treatment. Consequently, the applied method was effective to improve the adhesion of DLC coatings.