蠕墨铸铁抗高温冲击磨损性能的研究

Study on Impact Wear Resistance of Vermicular Cast Iron at High Temperature

蠕墨铸铁是高功率密度柴油机燃烧室气缸盖的主要制作材料,随着转速、爆压、功率密度的不断升高,气门与蠕铁气门座之间的频繁碰撞冲击导致冲击磨损加剧。利用自制冲击磨损试验机进行了不同环境温度(室温、300、400、500℃)和不同冲击频率(10、12、14 Hz)下的冲击磨损试验。结果发现,蠕墨铸铁的磨损量随着冲击次数的增加先快速增大随后趋于缓慢;随着冲击频率、工况温度的升高,磨损量先缓慢增大随后快速增大。材料冲击表面具有凹坑、犁沟、材料堆积的现象,且随着冲击次数、冲击频率、环境温度的升高,磨损面出现大量片状剥落层以及塑性变形。磨损机制主要以磨粒磨损和接触疲劳磨损为主,同时伴有轻微的黏着磨损和冲蚀磨损。

Vermicular cast iron is the main material for the cylinder head of high power density diesel engine combustion chamber.With the continuous increase of rotational speed,explosion pressure and power density,the frequent collision and impact between the valve and the compacted iron valve seat lead to the increase of impact wear.The impact wear test under different ambient temperature(room temperature,300℃,400℃,500℃)and different impact frequency(10 Hz,12 Hz,14 Hz)was carried out by using a self-made impact wear tester.The test results show that the wear amount of vermicular cast iron increases rapidly first and then tends to be slow with the increase of the number of impacts;however,with the increase of impact frequency and working temperature,the wear amount first increases slowly and then increases rapidly.The impact surface of the material has pits,furrows and material accumulation,and with the increase of impact times,the impact frequency and ambient temperature,many flake-like spalling layers and plastic deformation appear on the wear surface.The wear mechanism is mainly abrasive wear and contact fatigue wear,accompanied by slight adhesive wear and erosion wear.