ISSN   1004-0595

CN  62-1224/O4

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MoS2镀层类型对湿式铜基摩擦材料高速重载下的摩擦学行为影响

Effect of MoS2 Coating Types on the Tribological Behavior of Copper-Based Wet Friction Materials under High-Speed and Heavy-Load Conditions

  • 摘要: 功能组元表面镀层处理是1种在保持摩擦材料功能性同时提高摩擦材料强韧性的有效表面改性方法,有利于摩擦材料在高速重载工况下的可靠性提升. 面向不同表面镀层方法对铜基摩擦材料中重要的润滑组元MoS2的性能影响,采用SEM (扫描电镜)、EDS (能谱仪)、XRD (X射线衍射仪)和微米滑擦测试等现代分析检测手段,分析了含不同镀层MoS2润滑组元的本征特征、与基体形成的界面特性以及界面处的微摩擦性能;采用MM-3000摩擦试验机进行宏观湿摩擦学性能检测,系统对比了含不同镀层MoS2铜基摩擦材料在高速重载下的摩擦学行为. 结果表明:Ni镀层有效防止MoS2在烧结中分解,促使镀镍MoS2 (MoS2@Ni)与基体形成高强度的扩散结合界面,有助于平顺含MoS2@Ni铜基摩擦材料的摩擦曲线,并有效降低摩擦材料的磨损率. 而镀铜MoS2 (MoS2@Cu)在烧结过程中发生分解,与基体形成扩散-反应结合界面. 界面缺陷的存在导致含MoS2@Cu摩擦材料在高速高压下的磨损机制转化为犁削-剥层磨损.

     

    Abstract: The metal-based powder metallurgy friction material is a crucial component for high-speed and heavy-duty clutches, primarily consisting of matrix components and functional components (including lubrication components and friction components). Among these, the matrix components determine the physical and mechanical properties of the material such as strength, hardness, heat conduction, and heat resistance. The lubrication components are employed to eliminate vibration, reduce noise, adjust the coefficient of friction, and stabilize the friction process. On the other hand, the friction components predominantly influence the friction coefficient as well as wear resistance and adhesion resistance of the material. The surface coating treatment of functional components is an effective method for modifying surfaces, which can maintain the friction material's function while enhancing its strength and toughness. This approach contributes to improving the reliability of friction materials under high-speed and heavy load conditions. The aim of this study was to investigate the impact of various surface coating techniques on the performance of MoS2, as an important lubricating component in copper-based friction materials. A series of analysis and detection techniques, including SEM, EDS and XRD, were employed to investigate the morphology and intrinsic performance of MoS2 lubricating components with different coatings, the MoS2 and matrix interface characteristics. The micro-friction test was carried out to evaluate the interface bonding properties and micro-friction properties of Cu-matrix/MoS2 lubricating components with different coatings. The tribological behaviors of Cu-based friction materials (Cu-BFM) with different MoS2 were overall compared using the MM-3000 friction test. The result showed that both Ni and Cu coatings contributed to enhancing the interface performance between MoS2 and the matrix. However, it should be noted that Cu coating fails to prevent the decomposition of MoS2, leading to the formation of a limited amount of sulfide phase at the matrix/MoS2 interface with inherent defects in the diffusion-reaction interface. On the other hand, Ni coating optimized the interface performance by effectively inhibiting MoS2 decomposition during sintering and facilitating the formation of a good diffusion bonding interface between nickel-plated MoS2 (MoS2@Ni) and the matrix. The Cu-based friction material (Cu-BFM) containing copper-coated MoS2 (MoS2@Cu) exhibited a higher friction coefficient at lower rotation speeds (3 000 r/min) due to the decomposition of MoS2. However, at higher rotation speeds, MoS2@Ni demonstrated a higher friction coefficient and a greater stability factor owing to its stabilizing effect on the friction process. In terms of wear performance, MoS2@Ni exhibited a significantly superior effect on the wear resistance of friction materials compared to MoS2@Cu. Particularly at high rotating speeds, MoS2@Ni effectively suppressed the occurrence of fatigue wear in friction materials, resulting in a more than 30% reduction in the wear rate of friction materials containing MoS2@Ni when compared to those containing MoS2@Cu. Regarding the wear mechanism, friction materials containing both types of MoS2 exhibited ploughing wear as the dominant mechanism at low rotational speeds, while at high rotational speeds, the presence of MoS2@Cu in friction materials led to a transition from ploughing wear to a combination of ploughing and fatigue-induced delamination wear.

     

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