铝制内燃机缸体内壁铁基涂层的制备及摩擦学特性的研究

发布时间：2018-08-02 11:19

【摘要】：随着汽车工业的快速发展,能源和环境污染问题变得越来越严峻。通过减轻汽车的重量和提高燃油经济性,可以有效地降低汽车的能耗,并且起到保护环境的效果,因而各国的汽车生产企业和科研机构都在进行相关的研究。国际权威机构发布的研究报告指出燃料中超过一半都被汽车自重所消耗,更有研究机构指出汽车自重每减轻10%,燃油的消耗也可相应减少十分之一以上。发动机不但是汽车上非常重要的部件之一,而且也是重量最大的零件之一,在汽车行业中超过一半以上的车辆均采用铝合金材料来制造发动机。虽然使用铝合金材料制造的发动机使得汽车重量减轻的程度很大,但其无法满足缸体高耐磨性这一技术要求,通常采用嵌入铸铁缸套或者采用高硅铝合金作为缸体的材料,但两者都存在很多技术上不足。在铝合金缸体内壁上利用电弧热喷涂技术制备出厚度大约在200-300μm之间的涂层,增加的重量几乎可以忽略,可以灵活选择喷涂所使用的丝材,喷涂和机械加工可以在缸体内壁上依次进行,精度也有保障,成本也很低。为了在铝制发动机缸体内壁制备出致密、均匀、与基体结合强度高、高耐磨的涂层,首先设计并制造研制出可用于发动机缸体内表面喷涂的专用热喷涂枪体,该枪体可以完成旋转喷涂功能,并能保证喷涂层的结合性能和喷涂质量。将选用的4Cr13、65Mn和08Mn2Si铁基丝材喷涂到基本表面,利用金相显微镜和扫描电子显微镜,观察并分析涂层的组织结构和形貌特征,并借助能谱(EDS)分析和XRD图谱分析,得出涂层中所含元素的特点及所含物相的成分。采用DPT-5着色渗透剂和吸附介质(显像剂),观察液体在涂层孔隙中渗透情况,从而得出涂层中孔隙结构的分布及形貌。利用ImageJ软件得出孔隙轮廓图片并计算出各涂层的孔隙率,然后利用MMU-5G材料端面高温摩擦磨损试验机在干湿环境下,采用不同应力,进行耐磨性试验并与灰铸铁对比,得出涂层的失重量、销的失重量、涂层摩擦系数、涂层磨痕金相图,结合涂层组成物质特点、孔隙结构特点及孔隙率进行涂层耐磨性分析,通过分析得出涂层硬度、涂层中的孔隙结构、孔隙率的大小、孔隙的分布状况等与涂层摩擦磨损性能之间的关系,并与建立的涂层数据模型进行对比验证。实验结果表明,涂层的结合强度与涂层的孔隙率和氧化物占比有关。涂层的结合强度与涂层中氧化物含量以及涂层的致密度成正比关系。在干摩擦条件下,显微硬度最大的65Mn涂层的磨损量最小,而显微硬度最小的08Mn2Si涂层磨损量最大。涂层中氧化物的含量决定了涂层的摩擦性,涂层中的氧化物具有明显的润滑作用,从而增加了涂层的耐磨性,涂层中氧化物的含量越高,摩擦过程中涂层表面形成的润滑膜越完整,涂层的摩擦系数越小。在浸油摩擦条件下,孔隙率及孔隙结构的分布决定了涂层的摩擦性。与表面连通孔隙在摩擦过程中油液进入孔隙中,在摩擦时储存的油液不断的输送到摩擦界面,从而起到了减摩的作用。由此得出结论,自制的内孔喷枪可以实现铝制缸体内壁的涂层的制备,涂层制备中粒子堆垛出现的孔隙结构,在缸体实况工作中,可以起到很好的减摩作用。因此利用电弧热喷涂技术在铝制发动机内壁制备耐磨涂层,可以取代在铝制缸体内嵌入铸铁缸套或者采用高硅铝合金作为缸体的方法,同时为内燃机铝制发动机缸体内壁耐磨涂层的制作提供了理论参考。
[Abstract]:With the rapid development of the automobile industry, the problem of energy and environmental pollution becomes more and more serious. By reducing the weight of the car and improving the fuel economy, the energy consumption of the automobile can be reduced effectively, and the effect of protecting the environment is effective. Therefore, the automobile production enterprises and the research institutions of various countries are carrying on the related research. More than half of the fuel is consumed by car weight, and more research institutions point out that the car's self weight is reduced by 10% and fuel consumption can be reduced by more than 1/10. More than half of the vehicles are made of aluminum alloy materials to make engines. Although the engine made using aluminum alloy material makes the weight of the car lighten, it can not meet the technical requirements of the high wear resistance of the cylinder, usually using the embedded cast iron cylinder liner or the high silicon aluminum alloy as the cylinder material, but both are stored. On the inner wall of the aluminum alloy cylinder, the coating with the thickness of about 200-300 m is prepared on the inner wall of the aluminum alloy cylinder. The weight of the increase is almost negligible. The wire material used can be chosen flexibly. The spraying and machining can be carried out in turn on the inner wall of the cylinder body, the precision is also guaranteed and the cost is very low. In order to make the inner wall of the aluminum engine cylinder tight and uniform, the coating with high bonding strength and high wear resistance is designed and manufactured, first, a special thermal spraying gun which can be used to spray the body surface of the engine cylinder is designed and manufactured. The gun body can finish the function of rotating spraying, and can ensure the bonding and spraying quality of the spraying layer. 4Cr13,65Mn and 08Mn2Si iron base wire were sprayed to the basic surface. The microstructure and morphology of the coating were observed and analyzed by metallographic microscope and scanning electron microscope. The characteristics of the elements in the coating and the composition of the phase contained in the coating were obtained by means of energy spectrum (EDS) analysis and XRD Atlas. The DPT-5 coloring permeation agent and adsorption medium were used. Mass (imaging agent), observe the permeability of liquid in the pores of the coating, and then get the distribution and morphology of the pore structure in the coating. Using the ImageJ software to get the pore profile picture and calculate the porosity of each coating, then use different stress and wear resistance test in the dry and wet environment by using the high temperature friction and wear test machine of the end face of MMU-5G material. Compared with gray cast iron, the loss weight of the coating, the loss weight of the pin, the friction coefficient of the coating, the gold phase diagram of the coating mark, the analysis of the wear resistance of the coating, combined with the characteristics of the composition of the coating, the characteristics of the pore structure and the porosity, were analyzed. The hardness of the coating, the pore structure in the coating, the size of the porosity and the distribution of the pores were obtained by analysis. The experimental results show that the bonding strength of the coating is related to the porosity of the coating and the ratio of oxide to the coating. The bonding strength of the coating is proportional to the oxide content in the coating and the density of the coating. Under dry friction, the hardness of the coating is hard. The wear of the 65Mn coating with the largest degree is the smallest, and the 08Mn2Si coating with the smallest microhardness is the largest. The oxide content in the coating determines the friction of the coating. The oxide in the coating has obvious lubrication, which increases the wear resistance of the coating. The higher the content of the oxide in the coating, the coating surface is formed during the friction process. The more complete the lubricating film is, the smaller the friction coefficient of the coating is, the friction of the coating is determined by the porosity and the distribution of the pore structure under the oil immersion friction condition. The oil liquid is transported into the pores during the friction process with the surface connected pores, and the oil stored in the friction is continuously transported to the friction interface, thus the effect of friction reduction is obtained. It is concluded that the self-made inner hole spray gun can prepare the coating of the inner wall of the aluminum cylinder, and the pore structure of the particle stacking in the preparation of the coating can play a very good antifriction effect in the actual work of the cylinder body. Therefore, the wear resistance coating of the inner wall of the aluminum engine can be prepared by the arc thermal spraying technology, which can be replaced in the aluminum cylinder. Cast iron cylinder liner or high silicon aluminium alloy is used as cylinder block, which provides a theoretical reference for the fabrication of wear resistant coating on the inner wall of aluminium engine cylinder block.
【学位授予单位】：沈阳工业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG174.4

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