Preparation Process Of MoS₂/TiO₂ Micro-arc Oxide Film Grown On The Surface Of TC4 Titanium Alloy

Titanium alloys with high specific strength,corrosion resistance,heat resistance and other good comprehensive properties and high structural benefits,widely used in aviation,aerospace,shipping,biomedicine and other fields.However,the surface hardness of titanium alloys is low and wear resistance is poor,especially when titanium alloys contact with other metals,adhesion wear and fretting wear are easy to occur,which leads to contact corrosion,which seriously restricts the further application of titanium alloys.A high hardness oxide ceramic film can be formed on the surface of titanium alloy by micro-arc oxidation,which greatly improves the tribological properties of titanium alloy.However,the friction coefficient of the film is too high and the loss is serious.In this paper,TC4 composite film was prepared on the surface of titanium alloy by micro-arc oxidation technique,and MoS₂/TiO₂ composite film was prepared on the surface of titanium alloy by micro-arc oxidation.The effects of electrolyte additives on morphology,film structure and wear properties of MoS₂ in situ synthesis were studied.A single optimization method is used to optimize the electrical parameters.The parameters are as follows:forward voltage280V-320V,negative voltage 120V-140V,duty cycle 15%.The power supply frequency is500 Hz.Using the optimized electric parameters and electrolyte formula,MoS₂ was synthesized from the solution in the process of micro-arc oxidation and the ceramic layer containing MoS₂ was prepared.The hardness,composition,phase composition and surface morphology of the film were investigated.The surface roughness and friction and wear properties were analyzed to evaluate the performance of ceramic coating.The results show that:The existence of MoS₂ was detected on the surface of the composite ceramic coating,which proved that the self-lubricating particle MoS₂ was successfully formed and introduced into the ceramic coating.The results showed that when the content of Na₂S was 20 g/L and Na₂MoO₄ was about 3.5 g/L,the pore size of the surface of the composite film was small and the distribution was uniform,and the content of MoS₂ in the film increased with the increase of Na₂S content.However,the content of Na₂MoO₄ had little effect on the content of MoS₂ in the film.Compared with the ordinary micro-arc oxidation coating,the ceramic layer prepared by adding MoS₂ particles directly to the electrolyte,the ceramic layer prepared by introducing MoS₂ into the electrolyte by this method of chemical synthesis has a smoother surface and a smaller roughness,and the surface of the ceramic layer is more smooth and the roughness of the ceramic layer is smaller.The friction coefficient is also smaller and less fluctuating.At high temperature,the ceramic layer prepared by introducing MoS₂ into the electrolyte by the method of chemical synthesis is better than the ordinary micro-arc oxidation layer,and the ceramic layer prepared by adding MoS₂ particles directly to the electrolyte has better friction properties.