ISSN   1004-0595

CN  62-1224/O4

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Ni3Al基高温自润滑复合涂层的制备和摩擦学性能

Preparation and Tribological Properties of Ni3Al Matrix Self-Lubricating Composite Coating

  • 摘要: 采用高能球磨结合喷雾造粒制备喷涂喂料,利用等离子喷涂方法制备Ni3Al基高温自润滑复合涂层,通过HT-1000销-盘式高温摩擦试验机测试大气气氛不同温度下涂层的摩擦磨损性能,并采用SEM、EDS和Raman等表征分析涂层微观组织、物相组成和摩擦磨损机理. 结果表明:涂层在25 ℃至800 ℃具有良好的自润滑性能,摩擦系数为0.14~0.42,磨损率为2.41×10–4~5.76×10–4 mm3/(Nm). 25 ℃到400 ℃之间,随温度升高,Ni3Al金属间化合物韧性和软金属银塑性变形能力均提高,形成了有效的转移润滑膜,从而提高了涂层摩擦学性能,涂层磨损形式主要为脆性断裂、磨粒磨损和黏着磨损;600 ℃时软金属Ag过度软化,BaF2/CaF2共晶脆-塑性转变不完全,磨损表面不能形成完整致密的润滑膜,摩擦系数和磨损率大幅升高,涂层的磨损形式主要为剥层磨损和磨粒磨损;800 ℃时磨损表面形成富含NiO、Ag2MoO4和NiCr2O4等高温润滑剂的连续光滑釉质层,摩擦系数和磨损率大幅降低,磨损形式主要为氧化磨损和黏着磨损.

     

    Abstract: In this study, a feed of Ni3Al matrix self-lubricating composite powder has been fabricated by high-energy ball milling combined with spray granulation methods. Then it was deposited on the steel surface by plasma spraying to form a self-lubricating coating. The friction and wear properties of the Ni3Al matrix self-lubricating composite coating at elevated temperatures in atmosphere were tested on a HT-1000 pin-on-disk type high-temperature tribometer. In addition, the microstructure, phase composition and wear mechanism of the coating were characterized and analyzed by scanning electron microscopy, energy dispersive spectrometer and Raman. The results show that the coating had a good self-lubricating property from 25 ℃ to 800 ℃, characterized by friction coefficients of 0.14~0.42 and wear rates of 2.41×10–4 ~ 5.76×10–4 mm3/(Nm). The wear mechanism can be explained as follows: (1) within temperature range 25 ~ 400 ℃, an effective transfer lubricating film formed on the worn surface due to the increase of the toughness of Ni3Al intermetallic and the improved plastic-deformation ability of soft metallic silver at higher temperature, thereby improving the friction and wear properties of the coating, the wear mechanisms were brittle fracture, abrasive wear and adhesive wear. (2) At 600 ℃, the wear surface was partially covered by a complete lubrication film due to the excessive softening of Ag and incomplete brittle-plastic transformation of BaF2/CaF2 eutectic, thus deteriorating the tribological properties, and then the wear mechanism was peeling and abrasive wear. (3) At 800 ℃, due to the formation of a continuously smooth enamel layer rich in high-temperature lubricant (NiO, Ag2MoO4 and NiCr2O4) on the worn surface, the friction coefficient and the wear rate were greatly reduced, and the wear mechanism was mainly oxidation wear and adhesive wear.

     

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