Study On Technology And Performances Of Ultrasonic-Electrodeposited Ni-TiN Composite Coatings

The synthesis of the composite layer is the process that one or several kinds of insoluble solid particles are adding into the electrolyte to be co-deposited with metal ions. The research of the composite layer has a history of twenty years, and remarkable effects have been achieved in the aspects of strengthening the surface of materials. However, the solid particles used are most in micron scale, and the performance of composite layers contained them cannot match the requirement of the rapid developments of science and technology. Nano-composite layers are the composite layers obtained by adding solid nano-particles into the electrolyte and making them co-deposit with metal ions. Great progress has been made in the application of nano-particles in electroplating, chemical plating and brush plating in order to obtain composite layers with better performance, such as hardness, wear resistance, etc., than normal composite layers. However, the research and application of nano-composite layers are limited by the development of composite layer itself and current limit knowledge of nano materials. Now the performance of composite layers that have been developed are far less satisfying for the rapid development of the industry, so it is necessary for us to do extra work on how to farther improve the performance of composite layers. In this paper, Ni-TiN nano-composite layer was obtained by ultrasonic-electrodeposition method. The mechanism of the compound effects of ultrasonic-electrodeposition was discussed, and several factors that have effected on the formation of the composite layer were concluded. Optimized technical parameters, including the contents of the nano-particles, the current density, the composition of the electrolyte, the type of the agents and the power of ultrasonic waves, were confirmed by orthogonal experimental analysis. We observed the surface morphology and metallurgical structure of composite coatings with SEM and HREM. The micro-rigidity, adhesion, wear resistance, corrosion resistance of the surface of the composite layers are compared and analyzed as well as the thickness of the layers. It was shown by the results of the research work that, a composite layer contained nano-sized Ni grains and TiN nano-particles can be obtained by the ultrasonic-electrodeposition method, which not only has a fine and even surface but also shows excellent performances, such as micro-rigidity, wear resistance and corrosion resistance, and a similar adhesion with normal composite layers.