The Research On Wear-corrosion Mechanisms Of Electrodeposition And Laser-Electrodeposition Ni-Based Alloy And Composite Coatings

Electrodeposition is an important approach to enhance wear and corrosion resistance of parts of machines.Ni-based alloy and composite coatings which have both good wear resistance and fine corrosion resistance can be used as a solution to the erosion problem in chemical industry,petroleum ,electric power ets departments. Composite coatings is a key aspect during the development of electrodepostion .but in general,the adding of second hard phase led to a decrease uniformity of structure .as a result, the corrosion resistance of composite coatings decreased as a cost of increase of wear resistance, which limit composite coatings'application extension.To develop electrodeposition technology , in this paper , the electrodeposition technology and laser techonlogy are combined , a new method of electrodeopsition of metal and alloys simultaneously with laser irradiation is applied to obtain composite coatings which is called laser-electrodeposition. Laser has high energy, the deposition rate increased signifiantly by laser irradiation results from the increase of temperature on the metal/solution boundary surface., at the same time , stronger interfacial bonding ,higher hardness and better corrosion resistance can be obtained in Ni-W-Co/SiCp composite coatings .The weightless in an hour of coatings are basis to assess the wear-corrosion resitance under different load in mediums of 5%H2SO4 solution and 5%H2SC>4 +3.5%NaCl solution. The result showed that: laser-electrodepostion Ni-W-Co/SiCp composite coatings exhibited best wear-corrosion resistance in both mediums, in 5%H2SO4 solution , Ni-W-Co/SiCp composite coatings had better wear-corrosion resistance than Ni-W-Co alloy coatings, but in 5%H2SO4 +3.5%NaCl solution, with the increase of abrasion loads, the wear-corrosion resistance of Ni-W-Co/SiCp composite coatings decreased quickly,when the load was more than SON, Ni-W-Co alloy coatings wear-corrosion resistance were better.Wear and corrosion involve mechanical and electrochemical mechanisms, and the combined action of these mechanisms often result in significant mutual reinforcement. To measure the effect on wear-corrosion resistance of the chemical and abrasion wear separately at the same time, wear-corrosion synergism rate is selected to indicate the nature and degree of the chemical and abrasion wear. From many tests and analyses,conclusions are made as followted :when thecorrosion medium is 5%H2SO4 solution, mechanical property is a main factors which affect the wear-corrosion resistance ,with the increase of corrosion ablitily of medium, electrochemical property begins to play more and more imporant roles.