铜基粉末冶金闸片的抗热震性能研究

Thermal shock performance of copper-based powder metallurgy brake pads

铜基粉末冶金闸片具有高导热性、优异的摩擦学性能和高适应性,被广泛用于高速列车闸片。本文对粉末冶金闸片进行抗热震试验,模拟闸片在制动过程中的温度变化,并对闸片尺寸、粘接强度及显微组织进行测试分析,以验证铜基粉末冶金闸片的可靠性。结果表明:在宏观角度上(毫米级),经过热震循环后,闸片表面未发现明显裂纹;闸片的整体尺寸均有所增加,在低温循环阶段,尺寸增长较慢,高温循环后,急剧增加;在微观角度上(微米级),闸片背板和钎料层结合较好,界面较平直,与摩擦块无明显界面;经热震循环后,摩擦块内部组织变得疏松,与钎料层的结合程度下降。

Copper-based powder metallurgy brake pads are widely used as brake pads for high-speed trains because of their high thermal conductivity,excellent tribological properties and high adaptability.In this paper,thermal shock tests were conducted on the powder metallurgy brake pads to simulate the temperature change of the pads during braking,and the dimensions,bond strength and microstructure of the pads were tested and analyzed to verify the reliability of copper-based powder metallurgy brake pads.The results show that in the macroscopic perspective(millimeter level),no obvious cracks are found on the surface of the brake pads after the thermal shock cycle.The overall dimensions of the brake pads are increased,and the dimensions increase slowly in the low-temperature cycling stage,and then dramatically after the high-temperature cycling.In the microscopic perspective(micrometer level),the brake pads back plate and brazing layer are better bonded with a straight interface and have no obvious interface with the friction block.After the thermal shock cycle,internal organization of the friction block becomes loose and the degree of bonding with the brazing layer decreases.