Study On The Properties Of The Ni-Mo And Cr-Mo Coatings Prepared By Laser Cladding

The physical performance and corrosion resistance of the Cr-Mo and Ni-Mo alloy is excellent. The microstructure, hardness and corrosion resistance of the Cr-Mo coating with different amount of Mo in Cr matrix and Ni-Mo coating is studied in this paper. The best coating is found finally by comparing of these two kinds of coating. It can play a very important role in oil and ocean exploitation areas, having a very bright future as well.Cr、Cr-Mo and Ni+40%Mo coating are prepared on the substrate of Q235steel with the Nd:YAG laser. The well bonded and condensed coatings are obtained by choosing the appropriate laser cladding parameters., The phase of the Cr coating is mainly Cr, the phase of Cr-Mo coatings except Cr+15%Mo are chromium base solid solution, the phase of Cr+15%Mo coating is Cr3Mo, the phase of Ni-Mo coating is nickel base solid solution.Micro-hardness and corrosion resistance testing show that the hardness of Cr and Cr-Mo coating increases with the increment of the Mo content. The hardness of the coating with20wt%Mo reaches621.28HV0.2, which is more than3.5times of the matrix. And the hardness of the Ni-Mo coating reaches637.075HV0.2.Cr+15%Mo coating has the best corrosion resistance in Cr and Cr-Mo coatings, its corrosion current density is7.320×10-6A/cm2. However, the corrosion current density of Ni-Mo coating is4.295×10-8A/cm2. So the Ni-Mo coating has the best corrosion resistance. The corrosion product of Ni-Mo coating is MoO2, MoO2can promptly generate a very dense passivation membrane equiaxed in shape on the surface of the Ni-Mo coating which prevent coating surface from corroding.