Study On Wear Resistance Mechanism Of Fe Based Coating On Inner Wall Of Internal Combustion Engine Cylinder

The most common method of reducing the weight of a vehicle is using the light alloys instead of the traditional steel materials. Usually the cast iron engine is replaced by aluminum engine, which has the poor wear resistance. The solution of this problem is sprayed iron-based coating on the inner wall of the internal combustion engine cylinder.The wear resistance and anti friction mechanism of the Fe based coating on the inner wall of the engine cylinder was studied in this work. The results showed that the pore oil storage anti friction mechanisms and oxides of self-lubricating anti friction mechanism were the two main mechanisms of iron-based coating, which was important to the improvement of wear resistance.Three kinds of different coatings were prepared by selecting suitable process parameters by DPT-5 arc spraying equipment, which independently developed by Shenyang University of Technology. The matrix was gray cast iron. Three kinds of coating materials were 4Cr13, 08Mn2 Si and 65 Mn, respectively. Three kinds of coating microstructures were analyzed by means of the optical microscope and scanning electron microscope. XRD diffraction experiment of qualitative analysis was carried out on the coating surface. The results showed that there was oxide on the surface of the coatings.Using Image J software to deal with the low multiples metallographic photos of the coatings, and the porosity and oxide of the three coatings were measured.Through the coating bonding strength experiment, three kinds of bonding strength of the coating were obtained. The effect of the porosity and oxide in the coating was analyzed.The experimental results showed that the bonding strength of 65 Mn coating was the maximum with the value of 31.01 MPa. With the decreasing of the porosity and the content of the oxide, the bonding strength of the coating was increased. The microhardness of three kinds of coating and substrate were measured by the hardness test. The 65 Mn coating had the maximum hardness with the value of 421.4HV. The friction and wear test was conducted under the condition of the dry friction and oiled friction by the high temperature friction and wear testing machine. Three coatings and matrix of friction coefficient were obtained. The influence of the porosity and oxide of the coating on the wear resistance ofthe coating was studied, and the penetration test of the coating and microstructure analysis of the wear scar was studied. The results showed that the average friction coefficient of friction under the dry condition was much larger than immersed friction condition, which indicated that the coating pore can be improved by coating the anti friction. The mechanisms of iron-based coating were pore oil storage anti friction mechanisms and oxides of self-lubricating anti friction mechanism.