基于激光熔覆的缸套表面梯度材料制备及其摩擦学性能研究OA北大核心CSTPCD

As a new type of material whose performance changes with composition or structure,functional gradient materials are increasingly being applied to improve the tribological properties of mechanical components.In order to study the anti-wear and friction reduction effect of functional gradient materials on the surface of cylinder liners,a regular texture arrangement with a 30° angle was prepared on the surface of cylinder liners to explore the coupling effect of material and texture on the improvement of tribological properties. The ZS1115 diesel engine cylinder liner was selected for the experiment,and 80 mm x 120 mm cylinder liner slices were obtained through wire cutting.The material was wear-resistant alloy cast iron,and functional gradient materials were prepared.Firstly,a 30° groove was prepared on the surface of the cylinder liner with a laser marking machine,and then iron based powders with different nickel contents were melted into the groove by coaxial powder feeding.The process parameters during the melting process were slightly different.These were the parameters selected for the optimal cladding effect in the previous cladding experiment.After cladding,a part of the cylinder liner was cut by wire to obtain the cross-section of the cladding layer.The microstructure of the cladding alloy layer was analyzed from a microscopic perspective with a metallographic microscope,and the tribological properties of the functional gradient material cylinder liner prepared under a fixed load and speed were studied with a reciprocating friction and wear testing machine.During the test,the contact resistance between the cylinder liner and piston ring was collected to obtain the oil film lubrication condition between the friction pairs,and the friction change throughout the test was also collected.After the experiment,the three-dimensional feature parameters of the friction surface were obtained through a contact surface profiler.At the same time,the mass of piston ring before and after the test was recorded,and the mass wear of piston ring before and after the test was calculated. The metallographic analysis results showed that the microstructure of the cladding layer presented a gradient arrangement,and the cladding layer and the matrix material molecules and atoms interacted and diffused to form a good metallurgical bond.The functional gradient material prepared from powder with a grade of 350,a nickel content of 4.2％,and an iron content of 80％showed the most significant friction reduction effect,with an average friction coefficient reduction of 25.4％compared to the untreated control group.Moreover,this group had the highest average contact resistance in the experiment,which increased by 63.45％compared to the control group.Compared with the control group,the wear of piston ring in the test group with gradient materials was significantly reduced.The surface support index of the cylinder liner prepared with powder with a grade of 330,a nickel content of 9％,and an iron content of 70％was the highest at 0.78,an increase of 35％compared to the untreated control group.The preparation of functional graded materials with an angle of 30° can make the cylinder liner piston ring tribology system produce a stable lubricating oil film better in the working process,so as to reduce the friction and the friction coefficient,and at the same time enhance its support ability and the ability to store lubricating oil,so that the friction coefficient of the prepared cylinder liner can be significantly reduced.The material with a grade of 350 has the best effect on improving tribological properties.