Study Of Wear Resistant Composite Phosphating And Bonded Solid Lubricant Film

Oil lubrication and grease lubrication are traditional lubrication methods,but in some special conditions like high temperature,high pressure,high speed and so on,their application are restricted.Solid lubrication was developed,which can be used in these special conditions. Graphite and MoS₂ are universal solid lubricants.Solid lubrication films can be prepared in many ways.Bonded solid lubrication film is an easy way,so it is widely used.But the adhesion of bonded solid lubrication film and basal body is weak.In order to improve the adhesion,the K₂Ti₄O₉ whisker was added to graphite-MoS₂ solid lubricant to enhance the adhesion between bonded solid lubrication film and basal body. Besides,wear resistant composite phosphating was used before bonded solid lubrication film.Wear resistant composite phosphating and K₂Ti₄O₉ whisker work together to improve the adhesion and to prolong the wearing life of the bonded solid lubrication film.Wear resistant phosphate coating can be used as a solid lubrication film.A composite phosphating solution was developed according to the mechanism of phosphating film forming.The effect of process parameters on phosphate coating were investigated including various metal ions, temperature,time,acid rate etc.Wear resistance of composite phosphate coating was investigated too.It can be found from the testing results that the best phosphating process is Zn(NO₃)₂ 20g/L,Mn(H₂PO₄)₂ 60g/L, Mn(NO₃)₂ 15 g/L,Ni(NO₃)₂ 2 g/L,Ca(NO₃)₂ 2 g/L,tartaric acid 1g/L, some addition.60-70℃,10-15 min.Composite phosphate coating is a black film with fine acicular crystal.Surface-adjust before phosphating can improve the quality of phosphate coating.Composite phosphate coating significantly decreases the friction coefficient from 0.8 to 0.3 and increases the wear resistance of materials.Adhesion between phosphate coating and basal body is about 47.47N. Graphite-MoS₂ solid lubrication coating has great capability of decompression and lubrication,but in order to be used longer under high temperature and high pressure,adhesion between solid lubrication film and basal body need to be enhanced.According to former tests,adding the asbestos fibre to solid lubrication film can prolong its life and enhance its adhesion.But the asbestosis fibre does harm to people and environment.So another suitable additive material needs to be found.The K₂Ti₄O₉ whisker is a kind of fibre which is cheap and easy to be made. According to some reports,that it was added to the polyurethane material can improve its durability and hot deformation temperature.It can be supposed that it may play the same role in the solid lubrication.So in this research the K₂Ti₄O₉ whisker is added to the solid lubrication film composed of Graphite+MoS₂.The experimental result shows that with the K₂Ti₄O₉ whisker's add,the adhesion between solid lubrication and basal body is enhanced,the coefficient of friction of solid lubrication film is decreased,and the wearing life of the solid lubrication film is prolonged. Adhesion between bonded solid lubrication film and basal body is about 5.32N.Phosphating before bonded solid lubricant has great effect.With phosphating before spraying solid lubricant,the coefficient of friction of solid lubrication film is smoother,the wearing life of solid lubrication film is longer.Because composite phosphate coating is a black film with fine acicular crystal.It can absorb solid lubricant,increase the contact area between solid lubrication film and basal body,so as to enhance the adhesion between them.The adhesion can be improved from 5.32N to 11.28N.