铁铜基粉末冶金材料制动工况下的摩擦磨损性能

Friction and wear properties of iron-copper based powder metallurgy materials under braking conditions

采用MM3000型摩擦磨损试验机,在7种连续制动工况下分别测试铁铜基粉末冶金摩擦材料的摩擦性能和耐热性能,利用扫描电镜和能谱仪分析研究两种转速(等效半径线速度)下摩擦材料的磨损机理。结果表明:在线速度为19.40 m·s^(-1)时,随着面压增加,摩擦材料的动摩擦系数略有降低。在0.44 MPa面压下,动摩擦系数为0.267~0.312;在0.80 MPa面压下,动摩擦系数为0.258~0.308。在线速度19.40 m·s^(-1)、面压0.44 MPa、单位面积制动能量268 J·cm^(-2)的连续制动工况条件下,动摩擦系数波动较大,在其他工况条件下,动摩擦系数波动较小。随着制动能量的增加,7种连续制动工况下平均动摩擦系数在0.300~0.334之间,动摩擦系数均在0.250以上,无明显衰退现象,表明铁铜基粉末冶金摩擦材料具有较好的耐热性能。在线速度为19.40 m·s^(-1)工况下,铁铜基摩擦材料的摩擦磨损机理主要为磨料磨损及氧化磨损;在线速度为30.00 m·s^(-1)工况下,铁铜基摩擦材料的摩擦磨损机理主要为疲劳磨损及氧化磨损。

The friction properties and heat resistances of the iron-copper based powder metallurgy friction materials were tested by MM3000 friction and wear testing machine under 7 continuous braking conditions.The wear mechanism of the friction materials at two different rotate speeds(line speed in equivalent radius)was studied by scanning electron microscopy and energy disperse spectroscope analysis.The results show that when the line speed is 19.40 m·s^(-1),the dynamic friction coefficient of the friction materials decreases slightly with the increase of surface pressure,which is 0.267~0.312 at 0.44 MPa and 0.258~0.308 at 0.80 MPa.Under the continuous braking condition as the line speed of 19.40 m·s^(-1),the surface pressure of 0.44 MPa,and the braking energy in unit area of 268 J·cm^(-2),the dynamic friction coefficient fluctuates greatly,while under the other conditions,the dynamic friction coefficient fluctuates little.With the increase of braking energy,the average dynamic friction coefficient under 7 kinds of continuous braking conditions changes between 0.300~0.334,and the dynamic friction coefficient is above 0.250,without the obvious decline phenomenon,indicating that the iron-copper based powder metallurgy friction materials have the good heat resistance.Under the line speed of 19.40 m·s-1,the friction and wear mechanism of the iron-copper based friction materials is mainly abrasive wear and oxidation wear.Under the line speed of30.00 m·s1-,the friction and wear mechanism of the iron-copper based friction materials is mainly fatigue wear and oxidation wear.