| Magnesium alloy is widely used in automotive, aerospace, 3C products, military and other fields with its’ advantages.These years, people have used to prepare functional coating on the surface of magnesium alloy, in order to extend the service life and improve the comprehensive performance of the parts.However,With the more serious environmental conditions, considering the defects of corrosion of magnesium alloy.Traditional single functional coating and single surface modification technology can not adapt to the harsh conditions and the engineering application of complex physical environment.In this paper, we propose a method of preparing functionally gradient coating by using composite processing technology.The gradient coating which is made by optimizing the combination of surface modification technology can meet the needs of new engineering applications.By using the composite processing technology which is consisted of PIIID and Mechanical spraying in this project, Functional gradient coating of phenolic resin with different system of AlN/CrAlN/ MoS2 have been successfully made on the surface of the magnesium alloy. With the help of some advanced methods of testing,the study of the microstructure, mechanical properties, friction and corrosion propertie of different system of AlN/CrAlN/ MoS2 have found that: in the aspect of microstructure, the coating of AlN has(002) preferred orientation growth.the suface of CrAlN coating which is composed of Cr-Al-N solid solution is smooth and compact.The surface and the interior of the MoS2- phenolic resin coating have a large number of micro holes These growth defects are mainly the diffusion channels which are caused by gas diffusion in the process of coating curing.In mechanical properties,The interfacial bonding strength between the AlN layer and the substrate was significantly better than that of the AlN/CrAlN layer.furthermore,the coating which is made by ion implantation between substrate and the MoS2- phenolic resin coating can significantly improve the bearing capacity of the substrate surface.Increasing the resistance of the wearing of MoS2- phenolic resin coating.Under corrosive environment,The physical and chemical properties of intermediate transition layer have an important influence on the corrosion protection effect on the functionally gradient coating.the closer electrochemical properties to the magnesium alloy, the better corrosion resistance the functionally gradient coating showed. Research shows: AlN/MoS2- phenolic resin coating has better protective effect than AlN/CrAlN/MoS2- phenolic resin coating. In addition, paper also show that there is strong effect of coupling damage during the strong friction- corrosion abrasion coating process.that wil increase the speed of damage process. An ion implantation /AlN transition layer which is between magnesium alloy and the top MoS2- phenol resin coating can effectively inhibit or delay the occurrence of galvanic corrosion, and selection and design of transition layer should be based on the electrochemical performance of the principle.This paper summarizes the coating microstructure formation mechanism and characteristics of the functionally gradient coatings with the different system AlN/CrAlN/ MoS2- phenolic resin. Given a reasonable explanation and a theoretical basis of coatings under the wear and corrosion environment, through the establishment of the intrinsic constitutive relation of microstructure, mechanical property, mechanical property and corrosion behavior of the coating.The mechanism of the wear and corrosion resistance of coating and the mechanism of wear failure were described in this paper. |
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