Effect of SiCP addition on nanoenvironmental protection composite coating of AZ91D magnesium alloy

Abstract

In order to further expand the application of magnesium alloy, and improve its corrosion resistance and wear resistance in an environmentally-friendly way, Ni-P-nano SiCP deposition coating was prepared on the surface of AZ91D magnesium alloy by direct chemical deposition without chromium and fluorine. The effects of SiCP addition on the morphology, composition, phase and properties of the deposited coating were studied by SEM, EDS, XRD, hardness tester and electrochemical workstation. The results show that with the increase of SiCP addition, the deposition amount of particles on the surface of the deposition coating first increases and then decreases, the size of cellular structure gradually decreases and then increases, and the hardness and corrosion resistance first increase and then decrease. When the addition amount of SiCP is 1.2 g/L the deposition amount of particles is the largest, the dispersion strengthening and fine grain strengthening effect are the best, and the deposition coating is both uniform and dense, with a thickness of about 36 μm, which has good bonding with the matrix; the hardness of the deposited coating is 682HV, which is significantly higher than that of the magnesium alloy matrix. The corrosion potential is -0.397 V, which is 75% higher than that of magnesium alloy matrix. The corrosion current density is 6.18×10-7 A·cm-2, which is 4 orders of magnitude lower than the matrix.

Keywords

• az91d magnesium alloy
• direct chemical deposition
• sicp addition
• environmentally friendly
• ni-p-nano sicp
• corrosion resistance