热老化对热塑性聚氨酯水润滑轴承材料的性能影响

为了探究老化对水润滑轴承材料摩擦性能的影响，本文选用典型的水润滑轴承材料热塑性聚氨酯（TPU）作为研究对象，依照GB/T3512-2014热加速老化标准对材料进行老化处理。所有的摩擦磨损试验均在CBZ-1船舶轴系摩擦磨损试验机上进行，综合运用超景深显微镜、接触式表面轮廓仪、电子扫描显微镜等多种表面测试技术手段探讨了磨损过程中热塑性聚氨酯试样表面的磨损特征，探讨了不同老化状态试样的磨损机理。试验结果表明：70 ℃老化120 h热塑性聚氨酯的平均摩擦系数降低了57.5%；90 ℃老化600 h热塑性聚氨酯的平均摩擦系数上升了32%；通过FT-IR和Raman分析，随着老化进行，氢键化氨酯基增多，少量氨酯基的C-N键断裂。复杂的化学变化改善了热塑性聚氨酯的有序结构，增加次晶和结晶度，摩擦系数降低；进一步老化造成大分子在应力集中处断裂，使部分柔性分子链脱离基体，摩擦性能恶化。

Influence of Thermal Aging on the Performance of Thermoplastic Polyurethane Water Lubrication Bearing Material

In order to explore the effect of aging on the tribological properties of water-lubricated bearing materials, water-lubricated bearing materials thermoplastic polyurethane (TPU) were selected and aged according to GB/T3512-2014 thermal accelerated aging standard. All tests were carried out on CBZ-1 marine shafting friction and wear tester. The worn surface characteristics of aged TPU samples were analyzed by using the Ultra Depth of Field Microscopy, Contact Surface Profilometer and Scanning Electron Microscopy, and the wear mechanism of aged TPU under different aged conditions was discussed. The test results show that the friction coefficient of TPU decreased by 57.5% when the aged temperature was 70 °C and the aged durations were 120 h; while the friction coefficient increased by 32% when the aged temperature was 80 °C and the aged durations were 600 h. By using the FT-IR and Raman analysis, the amount of hydrogen bonding urethano groups increased, and a small amount of the C-N bond urethano groups broken with the ageing progressed. The ordered structure of TPU was improved because of the complex chemical changes, the friction coefficient decreased with the increased paracrystal and crystallinity. The macromolecule was broken at stress concentrates with the further ageing, which made several flexible molecular chain separated from the matrix, and then the tribological properties deteriorated.