Preparation And Measuring Of Au/nano-SiC Composite Coating

To improve the hardness and wear resistance of the gold coating, but not to decrease the corrosion resistance and electrical contact properties, Au/nano-SiC composite coatings were prepared in this paper by adding the nano-SiC particles into the gold coating with the methods of electrodeposition. The effects of the nano-SiC concentration in electrolyte, cathode current density, stirring rate, temperature of the electrolyte and pH of the electrolyte on the properties of composite electrodeposition were studied. The morphologies, micro-hardness, wear resistance, bond strength and electrical performance were measured and analyzed using SEM, EDS, XRD, XPS, TEM, EDX etc. The composite electrodeposition mechanics of Au and nano-SiC particles was simply discussed at last.A quantitative of nano-SiC particles were detected in the composite coatings and they were very uniform and almost did not agglomerated. Setting the content of nano-SiC particles in the coating as target, the optimum process parameters were determined which were the nano-SiC concentration in electrolyte 7.0g/L, cathode current density 1.5A/dm2, stirring rate 100rpm, temperature of the electrolyte 40℃and pH of the electrolyte 4.3.There was a great improvement in the micro-hardness and wear resistance of Au/nano-SiC composite coating than pure gold coating. The content of nano-SiC particles in the composite coating was the main factor influencing the micro-hardness and wear resistance of the composite coating. The more the content of nano-SiC in the composite coating was; the higher the micro-hardness was and the better the wear resistance was. Considering the wearing behaviors, the pure gold coating exhibited abrasive wear but the composite coating mainly presented fatigue wear.The bond strength of composite coating was bigger than that of pure gold coating. The result of tensile testing indicated the bond strength of composite coating is more than 60.02MPa. The difference in contact resistance of composite coating and pure gold coating was not obvious, which showed that the nano-SiC added in the coating has a little effect on the electrical properties of it.The composite electrodeposition mechanics of Au and nano-SiC fitted to the Guglielmi two steps adsorption model. The process of composite electrodeposition could be divided three steps and finally the composite coating with uniform nano-SiC formed.