Research On Tribological Properties Of Oxide Coating In Marine Environment

With the rapid development of human society,the abundant material resources in the ocean have attracted widespread attention.High-reliability marine engineering equipment is the basis for human exploration of the ocean.However,the strong corrosiveness of the marine environment exacerbates the wear of metal mechanical parts.This greatly shortens the lifespan of various mechanical components in the marine environment,and severely restricts the exploration and development of marine resources by mankind.Therefore,the development of anti-wear coatings suitable for different mechanical components in the marine environment can provide technical support for the life extension and reliability improvement of engineering equipment in the marine environment.The oxide coating has good corrosion resistance and abrasion resistance.This paper mainly uses three technologies anodization,micro-arc oxidation and plasma spraying to prepare different kinds of oxide coatings on the surface of titanium alloy and stainless steel,and study the microstructure,phase composition,hardness and friction and wear properties of different oxide coatings.Meanwhile,the tribological mechanism of two oxide coatings,micro-arc oxidation and plasma spraying in seawater environment is discussed.The main conclusions are as follows:1.Prepare TiO₂ oxide film layer by anodic oxidation technology.The results show that the voltage parameters have no effect on the microstructure and phase composition of the oxide film,but have a certain effect on the hardness,friction coefficient and wear rate of the oxide film.Compared with dry friction,all oxide film layers exhibit lower friction coefficient and wear rate in seawater,indicating that seawater has good lubricating properties and protects the film layer to a certain extent.In addition,the oxide film layer in dry friction is mainly adhesive wear,fatigue wear and abrasive wear.The main wear mechanism in seawater environment is slight abrasive wear.2.Micro-arc oxidation technology is used to prepare micro-arc oxidation ceramic coatings in four different electrolyte solutions of mixed acid,phosphate,phosphate-aluminate and phosphate-silicate.The results show that different electrolyte solutions have a certain effect on the microstructure,phase composition,hardness,friction coefficient and wear rate of the micro-arc oxidation ceramic coating.The four ceramic coatings all show a smooth friction curve and a low degree of wear in the seawater environment,which is mainly due to the discontinuous water film formed by the seawater on the coating surface has good lubricating properties.The different components in the seawater also have a certain impact on the friction and wear properties of the coating.Ca²⁺and Mg²⁺elements form Mg(OH)₂ and Ca CO₃ deposits on the coating surface to play a boundary lubrication effect;Na⁺and K⁺elements can make SiO₂ glue particles accelerate to condense into a silica gel film that adheres to the surface of the coating;active elements such as S and Cl react with Fe in the dual ball to form Fe₂S₃ and FeCl₃ shear films.These series of reactions have played a different degree of anti-wear effect on the coating.The main wear mechanisms of ceramic coatings in dry friction are adhesive wear and abrasive wear,while the wear mechanisms in seawater are abrasive wear and slight scratching.In addition,the wear resistance of the phosphate-aluminate ceramic coating is the most excellent.3.The Al₂O₃ spray coating is prepared by two technical methods:Atmospheric Plasma Spraying(APS)and Suspension Plasma Spraying(SPS).The results show that different technical methods have different effects on the microscopic morphology,phase composition and hardness of the coating.The APS coating presents a typical layered superimposed structure of splash flakes,with poor coating density,high porosity and large pore size;SPS coating presents a typical superposed structure of columnar particles,with dense coating structure and low porosity.During the friction experiment,the mutual cutting action between the coating and the grinding ball formed a dense friction film between the two contact surfaces.This makes the two coatings exhibit a stable friction state and high wear resistance in dry friction and seawater environments.The wear mechanism of the two coatings in dry sliding friction is mainly abrasive wear,fatigue wear and adhesive wear.The wear mechanism in the seawater environment is mainly slight abrasive wear.