Research On Microstructure And Tribological Behavior Of Ni-based Composite Coatings Prepared By Plasma Spraying

Plasma spraying technology is an important surface modification technology of thermal spray, which has a wide application in automotive, aviation, aerospace and other fields. In addition, Metal Matrix Composite Coatings are widely used in various industrial fields owing to the high toughness and excellent properties of plastic combing with high hardness of other materials, so Metal Matrix Composite Coatings prepared by plasma spraying technique show the excellent mechanical and mechanical properties than a single material, which meets with the needs of the development material.Ni-based composite coatings prepared by plasma spraying, Meanwhile Ni-based alloy(Ni60AA powder) as the matrix phase with the adding tungsten carbide powder (WC-12% Co powder) as reinforcement to improve the low hardness and abrasion problems comparing with other materials. The results show that the phase composition of sprayed Ni-based composite coatings are not change significantly compared with the original powder, It can be seen that the as-sprayed coating is composed of nickel solid solution phase and reinforcing phase consisting of WC. SEM shows that the Ni-based coating exhibits the typical lamellar structure and low porosity. The zonal distribution of the additive enhanced nucleation of WC has showed that the agglomeration of the WC particles are easily deformable, indicating easily deformed WC particles are beneficial to improve the performance of Ni-based alloy coatings.Ni-based composite coating has been successfully prepared and the effects of the enhanced WC on the mechanical performance of Ni-based composite coating has been studied, the results showed that WC reinforced phase significantly improves the hardness of Ni-based composite coating, but the Young’s modulus of Ni-based coating decreases and H/E increases with the increasing of WC contents.The mechanism of tribological behavior of Nickel-based composite coatings were studied in imitation of engine operating conditions (lubrication, poor lubrication, dry friction).The results show sprayed Ni-based composite coatings significantly improves wear resistance property of aluminum alloy materials, especially the friction properties under boundary lubrication and dry friction condition, which can greatly improve the operational life of the engine block. In addition the porosity can temporarily store the particles as well as the function of the reservoir in the process of friction and wear, which has played a crucial role in improving the friction properties of the coating. The wear rate descend with WC particle increasing, the wear resistance property of aluminum alloy material, which expected to replace the cast iron cylinder liners.The results show that the Ni-based composite coatings and stainless steel substrates under artificial sea water condition show that the Ni-based composite coatings exhibit excellent wear corrosion resistance comparing with stainless steel, which can be used for the surface protection of stainless steel and provide an alternate method for surface protection of stainless steel.The corrosion and wear behavior mechanisms of Ni-based composite coating is studied in marine conditions (seawater lubricated, water lubrication, dry friction).The results showed that Ni-based composite coating improves the corrosion and wear properties of 316L stainless steel. The corrosion and wear analysis of experiments of Ni-based composite coatings and stainless steel substrates results under artificial sea water, indicating that Ni-based composite coatings exhibit excellent wear and corrosion resistance comparing to stainless steel. So Ni-based composite coatings can be used to strengthen the surface of stainless steel materials and to improve the performance of the moving parts which worked under marine conditions.