Modification of CrN Film by Mo Element Doping

CrMoN coatings with different Mo contents were deposited on 4Crl3 stainless steel by multi-arc ion plating (MAIP). The binding force, hardness and corrosion resistance properties of CrMoN coatings were investigated by adhesion scratch tester; hardness instrument, and electrochemical measuring instrument, respectively. The electrochemical corrosion property was studied in 3.5% NaCl solution, 1 mol.L-1 NaOH solution and 1 mol.L-1 H2SO4 solution. The results indicate that NaCl-type fcc-phased (Cr, Mo)N is observed in the CrMoN composite coatings; when the Mo content is 31.08%, diffraction peaks of Mo2N are observed in the direction of (311) and (111), with the coexisting of CrN, (Cr,Mo)N and Mo2N. When the Mo content is 7.09%, the largest binding force 57 N and micro-hardness (HV) 29623 MPa are obtained; when the Mo content reaches to 14.26%, the corrosion resistance of CrMoN coating is the optimum in 1 mol.L-1 NaOH solution; when the Mo content is 5.15%, the corrosion resistance of CrMoN coatings is the best in 3.5% NaCl solution. Corrosion mechanism of the coatings is mainly pitting corrosion with crevice corrosion and galvanic corrosion.