Study On The Preparation Of The Iron-base Coating Of Aluminum Internal Combustion Engine Cylinder Wall And The Tribological Properties

With the rapid development of automobile industry, energy and environmental pollution is becoming more and more serious. It can effectively reduce energy consumption of the vehicle by reducing vehicle weight and improve fuel economy, and have the effect of protecting the environment, and therefore all auto production enterprises and research institutes are in related research. The research report published by the international authoritative institutions pointed out that more than half of fuel is consumed by automobile weight, more research points out that the car every reduce 10% weight, the fuel consumption can be reduced by more than one over ten accordingly. Engine is not only one of the very important parts of the car, but also it is one of the biggest parts of weight, more than half of the vehicles in the automotive industry adopt aluminum alloy material to make the engine. Although using aluminum alloy material to make the engine of car, the degree of reduction in weight is very big, it can’t meet the cylinder high wear resistance of this technical requirements, it usually adopts embedded cast iron cylinder liner or high silicon aluminum alloy as the material of cylinder block, but both have a lot of technical deficiencies. On the inner wall of the aluminum alloy cylinder block, using electric arc thermal spraying technology on preparation of the thickness of about 200-300 microns coatings, the weight of the increase almost can be ignored, it can choose spraying silk material flexible, spraying and mechanical processing can be done in turn on the inner wall of the cylinder block,,the accuracy is guaranteed, and the cost is low.For aluminum engine cylinder wall was dense, uniform, and combination of high strength, high wear resistance coating matrix, and the first design and manufacture of thermal spraying gun can be used in the engine cylinder, the gun can complete spraying rotating function, and can ensure the combination of performance and the quality of spraying. It choose 4Cr13, 65 Mn and 08Mn2 Si iron base material spraying to the basic surface, observe and analyze the organizational structure and morphology of the coating characteristics by means of metallographic microscope and scanning electron microscope, with the analysis of energy spectrum(EDS) and XRD spectrum analysis, it is concluded that the characteristics of element content in the coating and the phase composition. With DPT-5 dye penetrant agent and adsorption medium(imaging agent), and observe the liquid penetration in the pore of coating, it gets the distribution of pore structure and morphology of the coating drawn. It is concluded that outline image of pore and calculate the porosity of the coating by using ImageJ software, then use of MMU-5G materials high temperature friction and wear testing machine in wet environment, using different stress abrasion, the experiment was carried out and compared with grey cast iron, it is concluded that the loss weight of coating, lose weight of pin, coating grinding crack friction, coefficient metallographic figure, combined with the characteristics of coating material, pore structure and porosity of the coating wear resistance analysis, through the analysis,it concluded that the coating hardness, the pore structure, the size of the porosity,and the relationship between pore distribution and the friction and wear performance of the coating, and compared with coating data model validation.The experiment result shows that the coating bond strength is related with the coating porosity and oxide proportion. The coating bond strength and oxide content of the coating and the density of coating is proportional relationship. Under the condition of dry friction, the largest microhardness of 65 Mn coating wear is minimum, and the smallest micro-hardness of 08Mn2 Si coating wear quantity is the largest. The oxide content of coating determines the grinding, the oxide of coating has obvious lubrication, thereby increases the wear resistance of coating, the content of oxide in coating is higher, the lubrication film in the process of friction in coating surface is more complete, the friction coefficient of the coating is smaller. Under the condition of oiled friction, the distribution of porosity and pore structure determines the grinding of the coating. The oil flows into open pore in the process of friction, the stored oil of friction continuously flows to the friction interface, it has played an important role in reducing friction. Thus concluded that the homemade inner hole gun can realize aluminum coating preparation for the inner surface of cylinder block, in the cylinder body of live work, the pore structure of the particle stacking in coating preparation, it has good anti-friction effect. So using electric arc thermal spraying technology in preparation of aluminum engine inner wear-resisting coating, can replace the embedded in aluminum alloy cylinder block cast iron cylinder liner and adopt the method of high silicon aluminium alloy as a cylinder body, at the same time, it provides a theoretical reference for the production of aluminum engine cylinder wall wear resistant coating of internal combustion engine.