活塞环用Mo及Mo基复合涂层的摩擦磨损性能研究

发布时间：2019-02-23 20:47

【摘要】：活塞环与缸套构成的摩擦副,是内燃机中重要的机构。同时也是内燃机中运行状况最为苛刻的部件。苛刻的工作环境决定了活塞环涂层材料的特殊性,纯陶瓷涂层易产生裂纹,而纯金属材料的耐磨性较差,金属陶瓷复合涂层往往表现出优异的耐磨性能。热喷涂Mo及Mo基复合涂层由于其良好的力学性能与摩擦学性能被广泛的应用与活塞环涂层的制造。本文采用大气等离子喷涂在45钢表面制备了Mo及30Wt.%Al2O3-Mo复合涂层,研究了Mo及Al2O3-Mo复合涂层的微观组织结构和力学性能;并考察了涂层与GCr15球配对副对摩时在常温至300°C时的干摩擦磨损性能;采用JSM-5610L型扫描电子显微镜分析了涂层的微观形貌和磨痕形貌;探讨了不同温度、不同载荷下Mo及Al2O3-Mo复合涂层的磨损机理。结果表明:1、等离子喷涂制备Mo涂层的孔隙率为8.13%,低于Al2O3-Mo复合涂层(10.06%)。Al2O3-Mo复合涂层硬度为406.5±8HV,高于纯Mo涂层,这归因于Al2O3陶瓷颗粒的弥散增强作用。纯Mo涂层与基体的结合强度42.2±3.2MPa,高于Al2O3-Mo复合涂层,Al2O3颗粒的加入一定程度上降低了Mo涂层的结合强度,两种涂层的层内结合强度均高于涂层与基体界面结合强度。2、与GCr15配对付对摩时,随着环境温度和载荷的升高,Mo涂层的摩擦系数与磨损率均逐渐升高。常温时,在10N~40N载荷下,Mo涂层的摩擦系数为0.43~0.7,磨损率为0.59×10-5mm3/N?m~2.989×10-5mm3/N?m范围内。在常温至300°C温度范围内,保持30N载荷不变时,随着温度的升高,摩擦系数和磨损率均逐渐增加;300°C对摩时,Mo涂层的摩擦系数和磨损率分别为1.14和11.2×10-5mm3/N?m,比常温时分别增加了120%和418%。常温下,Mo涂层的磨损机制以塑性变形、磨粒磨损为主,磨损类型为单一的机械类磨损。100°C~300°C温度下,Mo涂层的主导磨损机制逐渐转变为粘着磨损和氧化磨损,随温度的升高,涂层的粘着现象也越严重。3、与GCr15配对付对摩时,Al2O3-Mo复合涂层的摩擦学性能与纯Mo涂层区别较大。Al2O3-Mo复合涂层的摩擦系数和磨损率随加载载荷的升高而增加,而随环境温度的变化则呈先上高后降低的趋势。在300°C,30N载荷下,Al2O3-Mo涂层的磨损率最大值达到8.01×10-5 mm3/N?m。当环境温度为常温时,纯Mo涂层耐磨性能优于Al2O3-Mo复合涂层。但Al2O3-Mo复合涂层在100°C~300°C温度区4、间的高温摩擦学性能明显优于纯Mo涂层。Al2O3的加入增加了涂层的硬度,提高了涂层的高温抗变形能力,有效的降低了涂层与配对副之间的粘着现象,使得Al2O3-Mo复合涂层具有比纯Mo涂层更好的高温耐磨性能。
[Abstract]:The friction pair between piston ring and cylinder liner is an important mechanism in internal combustion engine. It is also the most demanding component in internal combustion engine. The harsh working environment determines the particularity of the coating material of piston ring. The pure ceramic coating is prone to crack while the wear resistance of pure metal material is poor. The cermet composite coating often shows excellent wear resistance. Thermal sprayed Mo and Mo based composite coatings have been widely used in the manufacture of piston ring coatings because of their good mechanical and tribological properties. In this paper, Mo and 30Wt.%Al2O3-Mo composite coatings were prepared on 45 steel by atmospheric plasma spraying. The microstructure and mechanical properties of Mo and Al2O3-Mo composite coatings were studied. The dry friction and wear properties of the coating and GCr15 ball pair were investigated at room temperature to 300 掳C, and the microstructure and wear trace of the coating were analyzed by JSM-5610L scanning electron microscope (SEM). The wear mechanism of Mo and Al2O3-Mo composite coatings at different temperatures and loads was discussed. The results show that: 1, the porosity of Mo coating prepared by plasma spraying is 8.13, which is lower than that of Al2O3-Mo composite coating (10.06%). The hardness of Al2O3-Mo composite coating is 406.5 卤8HVC, which is higher than that of pure Mo coating. This is attributed to the dispersion enhancement of Al2O3 ceramic particles. The bonding strength between pure Mo coating and substrate was 42.2 卤3.2MPa, which was higher than that of Al2O3-Mo composite coating. The bonding strength of Mo coating was decreased to some extent by adding Al2O3 particles. The in-layer bonding strength of the two coatings was higher than that of the interface between the coating and the substrate. 2. The friction coefficient and wear rate of the Mo coating increased with the increase of ambient temperature and load. At room temperature, the friction coefficient and wear rate of Mo coating are 0.430.7and 0.59 脳 10-5mm3/N?m~2.989 脳 10-5mm3/N?m under 10N~40N load. In the range of normal temperature to 300 掳C, the friction coefficient and wear rate increase with the increase of temperature when the load of 30N is kept constant. The friction coefficient and wear rate of the Mo coating are 1.14 and 11.2 脳 10 ~ (-5) mm / 3 / N ~ (-1), 120% and 418% higher than those at room temperature, respectively. At room temperature, the wear mechanism of Mo coating is plastic deformation and abrasive wear, and the wear type is single mechanical wear. At the temperature of 100 掳C ~ (300 掳C), the dominant wear mechanism of Mo coating is gradually changed into adhesive wear and oxidation wear, and with the increase of temperature, the main wear mechanism of Mo coating is changed into adhesive wear and oxidation wear. The more serious the adhesion phenomenon of the coating is. 3, the tribological properties of the Al2O3-Mo composite coating are different from that of the pure Mo coating when it is matched with GCr15. The friction coefficient and wear rate of the Al2O3-Mo composite coating increase with the increase of the loading load, and the friction coefficient and wear rate of the Al2O3-Mo composite coating increase with the increase of the loading load. However, with the change of ambient temperature, the temperature increased first and then decreased. The maximum wear rate of Al2O3-Mo coating was 8.01 脳 10 ~ (-5) mm3/N?m. under 300 掳C _ (30) N load. When ambient temperature is normal, the wear resistance of pure Mo coating is better than that of Al2O3-Mo composite coating. However, the high temperature tribological properties of Al2O3-Mo composite coatings in the temperature range of 100 掳C ~ 300 掳C are obviously superior to those of pure Mo coatings. The hardness of the coatings is increased with the addition of Al2O3, and the deformation resistance of the coatings at high temperature is improved. The adhesion between the coating and the pair is reduced effectively, and the Al2O3-Mo composite coating has better wear resistance at high temperature than the pure Mo coating.
【学位授予单位】：湖南科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK403;TG174.4

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