Characterization Of Zro2 Zrn Pvd Coated Az91d Magnesium Alloy

Abstract

ABSTRACT newlineThis study is an attempt made to explore the possibility of increasing the surface properties of the AZ91D magnesium alloy by applying a ZrO2/ZrN coating using PVD-RF sputtering process. For coating ZrO2, the PVD process parameter with multiple performance characteristics is optimized by using the Taguchi grey approach. L18 orthogonal array is selected for conducting the experiments on PVD coating. The validation experiment confirms that the proposed Taguchi grey method finds out optimal process parameter with multiple performance characteristics. The result shows an improvement in the micro hardness and surface roughness. Further, the performance characterizations such as SEM, EDAX, XRD, coating thickness, surface roughness, micro hardness and tensile strength were measured at optimal process parameter. newlineFor coating ZrN, optimization of the PVD process parameters is done by Taguchi-GA (Genetic Algorithm) method. L18 orthogonal array was used for conducting the experiments. The parameters such as type of gas, chamber pressure and power input of the PVD process can be optimized to get higher micro hardness and lower wear rate. Also, the type of wear was observed using SEM (Scanning Electron Microscope) microstructures. The multi objectives GA approach shows better optimal combination for attaining higher coating performances. The optimal combination has attained at parameter level G2CP1PI2 and validation test was conducted. newlineThe corrosion behaviour of heat treated AZ91D Mg alloy and ZrO2/ZrN coated AZ91D Mg alloy was investigated by potentio dynamic polarization test. The corrosion properties were studied by immersing the samples in NaCl solution for 6hrs, 24hrs and 48 hrs. . The surface morphology of the samples before and after corrosion was analysed. The results showed an increase in the pitting corrosion with increase in immersion hrs. newlineAlso the heat treated AZ91D Mg alloy and ZrO2/ZrN coated AZ91D Mg alloy were subjected to mechanical tests such as micro-hardness, tensile test and newlineii newlinewear study. The res