【摘 要】
:
气缸套是柴油机的关键零件之一,其内表面的耐磨性对柴油机寿命起决定性作用。然而船用低速柴油机气缸套工作环境恶劣,润滑条件差,缸壁的过度磨损、工作面易被拉伤等问题,影响了柴
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气缸套是柴油机的关键零件之一,其内表面的耐磨性对柴油机寿命起决定性作用。然而船用低速柴油机气缸套工作环境恶劣,润滑条件差,缸壁的过度磨损、工作面易被拉伤等问题,影响了柴油机的寿命和可靠性。等离子熔覆技术广泛应用于表面工程,其制得的涂层组织均匀致密且综合性能好。因此,利用等离子熔覆技术在气缸套表面制备耐磨减摩的自润滑涂层,有望成为提高气缸套耐磨性,进而提高船用低速柴油机使用寿命的有效途径之一。 本文以Ni包h-BN、Ni包MoS2作为自润滑剂与Ni60A、Ti合金粉末混合,采用同步送粉等离子熔覆技术在铸铁气缸套材料表面制备自润滑耐磨复合涂层,分别分析了h-BN体系、MoS2体系中自润滑剂及其添加量对熔覆层显微组织、物相、硬度以及不同温度(室温、200℃)下的摩擦学性能的影响。 结果表明:h-BN体系中,在室温条件下的摩擦磨损,等离子熔覆Ni60A-Ti、Ni60A-Ti-8%h-BN、Ni60A-Ti-15%h-BN涂层的摩擦系数及磨损量相差并不悬殊,h-BN未发挥明显的减摩作用。在200℃条件下进行摩擦磨损时,对比Ni60A-Ti涂层,等离子熔覆Ni60A-Ti-8%h-BN和Ni60A-Ti-15%h-BN涂层的平均摩擦系数显著降低;添加8%、15%h-BN等离子熔覆层在200℃条件下的磨损失重也明显降低,分别下降23.29%和31.51%。添加h-BN自润滑剂后涂层的摩擦磨损性能良好,且添加15%h-BN时的熔覆层呈现较好的减摩耐磨性能。 在以MoS2为自润滑剂的涂层体系中,添加不同含量MoS2等离子熔覆层的显微硬度均远大于铸铁基体的硬度。室温及200℃条件下进行摩擦磨损时,添加5%、7.5%、10%MoS2等离子熔覆层的摩擦系数以及磨损失重均比基体有大幅提升,且MoS2添加量为5%时涂层摩擦磨损性能最佳,磨损机制主要为粘着磨损。添加不同含量MoS2等离子熔覆层在90°及30°冲蚀角下抗冲蚀能力均明显优于铸铁基体,且90°比30°冲蚀角条件下的抗冲蚀性能好。其中,5%MoS2添加量等离子熔覆层的抗冲蚀能力最强。
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