The Tribology Of Plasma Sprayed Sulphide With Added Nano-SiC Composite Coatings

On the basis of tribology principle, the key point in designing self-lubricating and anti-wear composite coating is the choice of basis lubricants and wearable elements in reason. So, sulphide (FeS,WS₂,MoS₂) with excellent self-lubricating capability is selected as soft basis; nano-SiC ceramic is chosen as the hard basis for its eximious wear resistance property.Plasma spray is determined to prepare the sulphide composite coatings by doped nano-SiC ceramic. By using SEM,metallographic microscope, the microstructure morphology is investigated and analyzed. The tribological performances of sulphide/SiC composite coatings is carried out on pin-disk testing apparatus and sphere-disk testing apparatus.The experimental results show that various nano-SiC composition influence the structure of the sulphide composite coatings.Compared with pure FeS coating, the mirco-structure, the combinative intensity and surface roughness of FeS/SiC composite coatings become bad,and the porosity percentage rises. The mirco-structure and surface roughness of WS₂/SiC composite coating becomes better, and the porosity percentage declines, compared with pure FeS coating. The MoS₂/SiC composite coatings have many sphere particles, and its surface is rougher than FeS/SiC and WS₂/SiC composite coatings. In the three kinds of sulphide composite coatings, when nano-SiC is doped to above 20%, it can find that nano-SiC particles is distributing uniformly around the sulphide phase.The tribological experimental results show that: (1)FeS/SiC composite coatings possess better wear-resistance and lower friction coefficient than that of the steel substrate,especially 70%FeS+30%SiC composite coating. Porosity is able to store lubricating oil for the coatings, so it might be of value for the wear and friction of coatings. (2) WS₂/SiC composite coatings have better tribolgical capability than the steel substrate,especially in the rage of 30% of SiC additions.Under the oil lubricating condition, because of doped nano-SiC, composite coatings have lower wear.Analyzed wore surface morphology of the coatings,the coating produced abrasive wear. Under the high temperature(100℃and 200℃) dry condition, the composite coatings possess lower friction coefficient, mainly produced adherence wear. (3)MoS₂/SiC composite coatings declined the friction coefficient under the dry condition, and produced the adherence wear and abrasive wear. Using oil lubricant,the friction coefficient of composite coatings is stabile. Wore surface morphology produces abrasive wear.