【摘要】 为了延长"柱塞"的使用寿命,采用与"柱塞"相同的基体及涂层材料,应用火焰热喷涂方法制作了4种不同时间长度(2、5、10、12 min)的重熔处理试样,进行了弯扭疲劳试验,用SEM及EDX研究了涂层微观组织与性能。结果表明,当重熔时间过短时,涂层中镍粉大多没有完全熔融依然呈颗粒状,涂层内聚力及与基体结合力均不强,疲劳寿命较短。当重熔时间过长时,涂层中Si与O发生化学反应生成SiO2颗粒,成疲劳裂纹源,且保温时间越长,颗粒越大,疲劳寿命越低。在考虑小试样对大构件性能影响的基础上,确定了柱塞件的合理重熔保温时间,使柱塞的使用寿命得以显著提高。更多还原

【Abstract】 In order to prolong the useful life of "plunger" that was thermally sprayed with Ni-based self-fluxing alloy coating on 40Cr steel substrate,four types of thermally sprayed specimens which differed from heating time in the fusing process were prepared.The specimens has the same material as "plunger".Rotational bending fatigue tests were carried out,and coating microstructure of fracture surfaces were observed with the scanning electron microscope(SEM) and energy dispersive X-ray spectroscopy(EDX).The results show that specimens fused for shorter time exhibit has lower fatigue lifetime because both bonding of coating and substrate and cohesion of coating with nickel powder are still granular due to not completely fusion.Specimens fused for longer time exhibit has lower fatigue lifetime owing to chemical reaction of Si and O in the coating generated particle of SiO2 that become bigger with longer fusion time and become source of crack.The reasonable remelting holding time were confirmed after taking into account of the small specimen effects on the big component,and so the service life of the plunger were improved significantly.更多还原