Structural characterization and investigation of hardness and adhesion of fine grained stainless steel coatings produced by physical vapor deposition methods on carbon steel substrate

The purpose of this research is investigation of two fine grained stainless steel coatings produced by two physical vapor deposition methods, i.e. magnetron sputtering and cathodic arc evaporation, on a carbon steel substrate. The coatings were compared according to their structure, hardness and adhesion. In order to evaporate the target atoms, high power (3300 w) was applied on the cathode surface in cathodic arc evaporation method and argon pressure (105 Pa) was used in magnetron sputtering method. For comparison of these coatings, the same substrate temperature (300 ± 50 oC) and bias voltage (250± 50 V) and also similar deposition time (50 min) were used. XRD, EDS, SEM and FE-SEM methods were used for characterization of the coatings. Nano-indention and Vickers indenter tests were also carried out for evolving the hardness and adhesion of the coatings. The EDS analysis results showed that the magnetron sputtered coating had a composition similar to the target material, whereas the cathodic arc evaporation coating had a different composition. Also, the nano-indention test showed that the magnetron sputtered coating hardness increased up to about 890 Vickers, which is much higher than that of the cathodic arc coating (about 260 Vickers) and bulk 304 stainless steel (220 Vickers), due to its nano-crystalline structure. However, the sputtered coating adhesion was evaluated weaker than that of the cathodic arc coating, because of the existence of more cracks at the edges and also local spalling of the coating.