Study On P-MoS2/C Composite Solid Lubricating Coating

In this study,zinc phosphating is first applied to the surface of steel specimens,and the phosphating sample was soaked in solution containing MoS₂ particles,the MoS₂particles are embedded in the phosphating film by making use of the porosity and adsorption characteristics of the phosphating film,finally,after sealing and post-processing,a composite solid lubricating coating containing MoS₂ particles is formed on the surface of the steel?P-MoS₂ composite coating for short?.The preparation of P-MoS₂ composite coating is to first deposit a layer of phosphating film which is firmly combined with steel and thick and porous on the surface of steel.Taking the combination strength as the criterion,the formulation and phosphating process of the ideal zinc phosphating solution were obtained by orthogonal test.The optimized formula of zinc system phosphating solution is:Zinc Oxide?ZnO?20g/L,phosphoric acid?H₃PO₄?30ml/L,nitric acid?HNO₃?20ml/L,citric acid?C₆H₈O₇?1g/L,sodium nitrite?NaNO₂?0.4g/L,the temperature of the phosphating solution is 75 degrees centigrade,phosphating time is 15min,all indicators of phosphating film meet the requirements of national standard GB/T 6807-2001.The phosphated samples were soaked in deionized water,glycerol and anhydrous alcohol solution containing MoS₂ particles,respectively.It is found that the MoS₂particles can not be evenly mixed because the surface tension of the deionized water is too large,only the MoS₂ and anhydrous ethanol can be embedded in the phosphating coating.By comparing the friction and wear tests,it is found that the use of anhydrous ethanol is more suitable as the solvent of P-MoS₂ composite coating than the glycerol,and when the mass fraction of MoS₂ particles in the leaching solution reaches 20%,the P-MoS₂ composite coating has the lowest friction coefficient and wears loss.On the basis of P-MoS₂ composite coating,P-MoS₂/C composite coating withgraphite particles was further studied.It is found that when the P-MoS₂ composite coating is prepared,the addition of graphite particles in the solvent will further reduce the friction coefficient of the composite coating and improve the wear resistance of the coating.The test results show that when the ratio of MoS₂ to graphite in dip coating is 1:1,the friction coefficient of P-MoS₂/C composite coating is the lowest and the wear loss is the smallest.