Dual Ion Beam Sputtering for Chromium Nitride as an Alternative to Electroplated Hexavalent Chromium

Abstract

The hexavalent chromium used in chromium plating is so toxic that it is very hazardous to human body and even carcinogenic. Therefore, it is indispensable to develop an alternative deposition technique. To explore the feasibility of sputtering as an alternative technique for chromium plating, we investigated the dependences of the deposition rate, the phases, the hardness, the surface roughness and the corrosion-resistance of CrNx deposited on the high speed steel substrate by using a dual ion beam sputtering system on the rf-powers. The deposition rate of CrNx depends more strongly upon the rf-power for argon ion beam than that of the nitrogen ion beam. The hardness of the CrNx film can be maximized by optimizing the rf-power, so that the volume percent of the Cr2N phase in the film is highest. Amorphous films are obtained when the rf-power for nitrogen ion beam is much higher than that for argon ion beam. The CrNx film deposited by using the sputtering technique under the optimal condition provides corrosion-resistance comparable to that of the electroplated chromium.