Study On The Friction And Wear Properties Of Self-lubricating Coating With Three-dimensional Structure Deposited On 45 Steel By Electric Spark Deposition

In order to improve the lubricity and wear resistance of the surface of 45 steel,HB09-K3 type electric spark surfacing repair machine was used,and graphite and cemented carbide were used as electrode material,the self-lubricating coating with cemented carbide-graphite three-dimensional structure was deposited on 45 steel by electric spark deposition.First,the preparation parameters and deposition time were selected,and then the structure of the intermediate layer was designed.Finally,the microscopic morphology of surface and section of coating with three-dimensional structure were observed by scanning electron microscope,and the coating surface and cross section were analyzed by EDS.Workbench was used to simulate the friction process of coating,it was analyzed the change in stress,strain and temperature during the friction process.The reciprocating friction and wear testing machine was used to conduct friction and wear test on the coating,and the friction and wear properties of coating were studied.The single factor experiment was used to select the preparation parameters,it was found that the deposition quality of cemented carbide was best at pulse voltage50V,discharge frequency 40Hz,pulse width 40μs,and electrode rotation speed250r/min;the deposition quality of graphite was best at pulse voltage 60V,discharge frequency 60Hz,pulse width 50μs,and electrode rotation speed 250r/min.Self-lubricating coating with three-dimensional was prepared at the optimal preparation parameter,the deposition time of the bottom coating of cemented carbide was 6 minutes,the deposition time/area ratio of the intermediate layer of cemented carbide and graphite were respectively 2min/cm~2and 6min/cm~2,the top coating of graphite was 4 minutes,the coating thickness is thickest and the surface roughness is minimum.The appearance and morphology of the coating using SEM and Image J,and it was found that the coating surface is flat with a few pores and cracks under the best parameters.The section was showed by EDS,there was element diffusion between coating and coating,coating and substrate.The friction process of coating was simulated by Workbench,and analyzed the change rules of stress,strain,and temperature during friction process of coating.The results showed that the stress,strain and temperature of the contact area were increased with increasing of load and frequency.In the same condition,the stress,strain,and temperature suffered of coating with three-dimensional structure during the friction process were smaller than 45 steel and cemented carbide-graphite coating.In this thesis,tribological properties of self-lubricating coating with three-dimensional structure at pin-disk and ball-disk conditions were studied.The results showed that the friction coefficient and wear amount of coating with three-dimensional structure were lower than 45 steel and cemented carbide-graphite coating in the same condition.With the increasing of load and frequency,the friction coefficient was gradually decreased,while the wear amount was gradually increased.By analyzing the wear morphology,it was found that the friction surface of pin-disk was smoother and the friction coefficient and wear amount were smaller.