In order to obtain a dense thin coating film and improve corrosion resistance of coating steel, CrN thin film deposited on 0.37wtpercentC steel with multi-stage PVD method was studied. From an anodic polarization test in aerated 2percent H_2SO_4 solution, the steel coated with the multi-stage method showed better corrosion resistance than the speicmen coated with a common method. This is due to the decrease of small defects in the coating film by means of multi-stage deposition. Evaluation of corrosion fatigue strength on the multi-stage coating steel was performed under cantilever-type roating bending fatigue test in 3percent NaCl solution. From the experimental results, corrosion fatigue strength improved with the multi-stage coating as compared with those without coating. But an effort to improve corrosion fatigue strength was less in the multi-stage deposition than the common one, by contraries to the expectatin of corrosion resistance obtained from the anodic polarization test.
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