Study On Preparation And Performance Of Cu/Cu-MoS₂ And Cu/Cu-BN Self- Lubricating Composite Coating By ESD

The Cu/Cu-BN and Cu/Cu-MoS2 coating were prepared by the electric spark deposition process on the surface of high speed steel (W18Cr4V) and carbide (YG8,YW1) respectively. The influence of preparation parameters on coatings thickness, surface roughness, microstructure, friction and wear properties were studied. The chemical composition and corrosion resistance of coatings were analyzed.Cu/Cu-MoS2 coatings were prepared on the surface of high speed steel (W18Cr4V). Coatings were tested by X-ray diffraction (XRD). The results showed that there are only MoS2 and Cu in the self-lubricating coatings. The coatings thickness was measured by the overlay gauge. The results showed that coating thickness is firstly increased and then decreased with the increase in capacitance, deposition time and volume ratio of MoS2 and Cu. When the diameter of copper tube is 2.2mm, capacitance is second grade, the deposition time of Cu-MoS2 is 7 minutes, the coatings thickness are the best. The microstructure of the coatings was analyzed by using SEM photos of coating. It is found that coating surface is uneven and shows typical characteristics of ESD. Partial coatings exist cracks. When the diameter of copper tube is 2.2mm, capacitance is fourth grade, the deposition time of Cu-MoS2 is 7 minutes, the coating surface is the most smooth. The experiment of friction and wear was tested on a pin on disc friction and wear testing machine. The results showed that self-lubricating coating has higher than uncoated high-speed steel on the wear resistance, the relative wear resistance of self-lubricating coating is 3.67 times higher than the matrix. The wear volume and friction coefficient of the self-lubricating coating decreased firstly and then increased with the increase in capacitance and deposition time. The wear volume is firstly decreased and then increased with the increase in volume ratio of MoS2 and Cu, but the friction coefficient is decreased with the increase in volume ratio of MoS2 and Cu. When the volume ratio is more than 26%, the friction coefficient tends to be stable. When the diameter of copper tube is 2.2mm, capacitance is fourth grade, the deposition time of Cu-MoS2 is 7 minutes, the wear volume and friction coefficient of the self-lubricating coating are the minimum. The friction properties of coating is the best. The microstructure of wear surface showed that the wear mechanism of the self-lubricating coating has obvious characteristics of abrasive wear and fatigue wear.Cu/Cu-BN coatings preparing on the surface of high speed steel (W18Cr4V) were analyzed by X-ray diffraction (XRD). The results showed that there are BN and Cu in the coating. It can be seen from the SEM picture that the preparation of the coatings are roughness. When the diameter of copper tube is 2.2mm, capacitance is fourth grade, the deposition time of Cu-BN is 7 minutes, the Cu/Cu-BN self-lubricating coating surface is the most smooth. The coatings thickness was measured. The results showed that the thickness of the coating is not increased with the increase of deposition time. The result of friction and wear test showed that the wear mechanism of the self-lubricating coating is mainly dominated by abrasive wear when the load is 500g and the rotate speed is 400r/min.The Cu/Cu-BN and Cu/Cu-MoS2 coating were prepared by the electric spark deposition process on the surface of carbide (YG8,YW1) respectively. Coatings were tested by X-ray diffraction (XRD). Study on the phase composition of coatings by X-ray diffraction (XRD) experiment. The microstructure of the self-lubricating coatings was studied by using SEM photos of coating. The influence of different process parameters on microstructure of the coatings surface was analyzed. The results showed that there are BN (MoS2) and Cu in the coating. The influence of preparation parameters on microstructure of the coatings surface is similar to the coating on the high speed steel substrate.