Hydrothermal Synthesis And Tribological Properties Of MoS₂ Films On Titanium With Modified Surfaces

Molybdenum disulfide（MoS₂）films have excellent self-lubricating properties,and they can be applied on the titanium surface to improve the tribological properties of titanium.However,the surface characteristics of titanium significantly affect the growth and performance of hydrothermal synthesis of MoS₂films,and the research in this field is not enough.In this study,the laser texture,high temperature oxidation and micro-arc oxidation of titanium metal were performed to prepare the matrix surface with different characteristics.Then,the effects of modified surface characteristics and the concentration of sodium molybdate（Na₂MoO₄）on the synthesis and tribological properties of MoS₂ films were studied.Firstly,the hydrothermal synthesis and tribological properties of MoS₂ film on laser textured titanium surface were studied.The results show that the laser textured surface of titanium with MoS₂ film has a certain anti-friction and wear-resisting effect.The tribological properties of MoS₂ film synthesized on the mesh-like texture surface are better than those of fine grain texture and round pore texture.When the mesh side length is 0.4mm,the tribological performance of MoS₂ film synthesized on this surface is the best.However,it should be pointed out that the wear resistance of the MoS₂film on laser textured titanium surface is poor because it does not have contain wear-resisting phase.Secondly,the hydrothermal synthesis and tribological properties of MoS₂ film on oxidized titanium surface were studied.It was found that titanium dioxide（TiO₂）wear-resistant layer was formed on the surface of titanium after high temperature oxidation.Compared with 400℃and 800℃,TiO₂ produced by high temperature oxidation at 600℃for 3h is denser.The resulting TiO₂/MoS₂ film maintains a low friction coefficient within the friction distance of 150m.In order to further improve the wear resistance of the composite film,the TiO₂-LST/MoS₂ composite film was obtained by hydrothermal synthesis of MoS₂on the laser textured TiO₂ surface.Results show that the bonding and wear resistance of the composite film was improved.Finally,the hydrothermal synthesis and tribological properties of MoS₂ films on micro-arc oxidized titanium surface were studied.It is found that the micro-arc oxide film on titanium（Ti-MAO）has porous microstructure.In the hydrothermal process,MoS₂ grows along in the micropores and plays the role of sealing the pores.The comparative study found that when the micro-arc oxidation time was 20min,the friction coefficient of the Ti-MAO/MoS₂ film obtained after hydrothermal treatment was the lowest.By comparing the tribological properties of the films on different titanium surfaces,it is found that the friction distance of the Ti-MAO/MoS₂ film with low friction coefficient is the largest,and the anti-friction effect and wear resistance are the best.The effects of the concentration of sodium molybdate on the sealing effect and tribological properties of MoS₂ films were investigated.The results show that when the concentration of Na₂MoO₄ is 0.1mol/L,the sealing effect and tribological properties of MoS₂ film is the best.