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1、上海交通大学博士学位论文含磨粒油润滑条件下镀（涂）层摩擦学性能及其机理姓名：杜令忠申请学位级别：博士专业：材料加工工程指导教师：徐滨士;吴毅雄20050201I含磨粒油润滑条件下镀涂层摩擦学性能及其机理摘 要高风沙环境下空气中的沙尘很容易进入装备的润滑系统引起零部件的快速磨损失效本文针对这个影响装备使用寿命的关键技术难题依据零件失效形式及硬质点+软基体的设计思想提出采用镍基纳米颗粒复合电刷镀层3Cr13 高速电弧喷涂层12Co-WC 超音速等离子喷涂层等三种先进表面工程技术来提高材料在含细沙油润滑条件下摩擦磨损性能的技术路线采用 SEMTEM 及铁谱等技术研究了这三种镀涂层的显微组织相结构力学
2、性能以及各种因素对其在含细沙油润滑条件下摩擦学行为的影响这对于解决高原高风沙条件下装备的快速磨损延长装备寿命提高装备保障能力和战斗力具有重大的工程现实意义同时通过系统研究镀涂层在含细沙油润滑条件下的磨损机理和抗磨机制从理论上探讨与钢铁等均质材料不同的镀涂层的组织结构对摩擦学行为的影响对指导镀涂层的设计具有重要的学术意义通过对纳米颗粒复合镀层组织形貌和力学性能的研究发现纳米颗粒在复合镀层中呈三维均匀分布镀层组织细小致密由于细晶强化弥散强化和畸变强化镀层的硬度显著提高Al2O3SiO2SiCZrO2TiO2Si3N4及金刚石等七种镍基纳米颗粒复合电刷镀层在含细沙油润滑条件下的摩擦学性能对比实验表明
3、n-Al2O3/Ni 复合镀层具有最优的性价比当镀液中纳米颗粒含量为 20g/L时复合镀层具有最佳的摩擦学性能它在含细沙油润滑条件下的耐磨性显著高于快速镍电刷镀层及 45 钢基体进一步对 n-Al2O3/Ni 复合镀层的研究表明速度载荷沙粒含量沙粒尺寸镀层表面状态和摩擦副材质对复合镀层在含细沙油润滑条件下的摩擦学性行为具有较大影响镀层的磨损体积随载荷沙粒含量沙粒尺寸增加而增加II随滑动速度增加先减小当到一临界值时镀层的磨损体积又增加载荷和沙粒含量对磨损体积的影响较大而速度和沙粒尺寸对摩擦系数的影响较大镀层在低速低载下的磨损以磨粒磨损为主高速高载下的磨损转变为以材料的塑性变形和粘着磨损为主镀层表
4、面状态和摩擦副材质对纳米颗粒复合镀层的耐磨性影响较大表面未抛光时镀层的磨损体积是表面抛光时的 10 倍而与钢球对磨时镀层的磨损体积也是其与陶瓷球对磨时的 10 倍3Cr13 高速电弧喷涂层组织均匀致密 表面平整 涂层的孔隙率低结合强度高在含细沙油润滑条件下涂层的耐磨性比 38CrSi 钢提高 15以上12Co-WC 超音速等离子喷涂层具有比高速电弧喷涂层更优的表面组织和力学性能喷涂过程中WC 颗粒的氧化和分解少涂层主要由WC 和少量 W2C 组成在含细沙油润滑条件下涂层的耐磨性比灰铸铁提高 6 倍以上而且涂层的磨损体积随沙粒尺寸和沙粒含量增加变化较小在分析润滑状态沙粒和摩擦副对被磨材料的作用及
5、润滑油中磨屑形貌的基础上发现镀涂层在含细沙油润滑条件下的磨损机理为微观切削挤压脱落粘着磨损及低周疲劳剥落采用透射电镜等技术揭示了纳米颗粒复合镀层在含细沙油润滑条件下的抗磨机制弥散分布于复合镀层中的纳米颗粒通过改善镀层组织提高镀层的室温和高温硬度阻碍疲劳裂纹扩展以及减摩作用使镀层在含细沙油润滑条件下的摩擦学性能显著提高高硬的氧化物分布于高铬马氏体中提高了 3Cr13 高速电弧喷涂层抵抗磨粒切削的能力而涂层中的孔隙不但可以吸附并储油润滑而且还可以包容一部分沙粒因此涂层在含细沙油润滑条件下表现出良好的摩擦学性能12Co-WC 超音速等离子喷涂层高的硬度及软基体硬质颗粒的组织分布使涂层在含细沙油润滑条
6、件下具有良好的摩擦学性能III依据沙粒对材料表面的作用本文提出了一个材料在含磨粒油润滑条件下磨损体积计算的数理模型此模型与磨损实验数据吻合较好研究表明纳米颗粒复合镀技术可以修复 45 钢材质的轴承内外圈配合表面密封环配合面3Cr13 高速电弧喷涂或 12Co-WC 超音速等离子喷涂技术可以对轴类零件表面进行修复和强化应视零件成本而定而工作环境复杂的缸套表面宜采用具有较好结合强度及较高耐磨性的 12Co-WC 超音速等离子喷涂技术进行修复和强化依据模拟试验结果将三种先进表面工程技术应用于装备的强化和修复效果良好表面镀涂层技术在解决高风沙环境下材料的快速磨损方面具有广阔的应用前景关键词纳米颗粒电刷
7、镀层高速电弧喷涂超音速等离子喷涂油润滑磨粒磨损机理VTRIBOLOGICAL PROPERTIES AND WEAR MECHANISM OF COATINGS IN ABRASIVE CONTAMINANT OILABSTRACTIn dusty environments, fine sand particles entering the machine lubrication systems will accelerate the wear of the sliding components. In order to solve the problem, three surface coa
8、tings prepared by the nano- particle strengthened electro brush plating, the high velocity arc sprayed 3Cr13 steel and super-sonic plasma sprayed 12Co-WC particles technologies are selected according to the failure analysis and the material design concept of “soft matrix + hard particles”. The micro
9、structure, phase structure, mechanical performance, tribological properties, wear and anti-wear mechanism of the coatings in abrasive contaminant lubrication were examined using SEM, TEM and ferrograph technologies. And it is of the great industrial and academic importance to repair the equipment an
10、d design the surface coating in dust environment. The studies of the microstructure, morphology and the mechanical property of the composite coating show that the nano-particles are uniformly scattered in the coating in three dimensions and the microstructure of the coating is fine and dense. The ha
11、rdness of the coating is highly improved due to the fine-grain, dispersion and distortion strengthened effects. The electro brush plating n-Al2O3/Ni composite coating has the highest cost performance among the coatings strengthened by Al2O3SiO2SiC ZrO2TiO2Si3N4 and diamond nano-particles. When the n
12、ano-particle content in the solution is 20g/L, the n-Al2O3/Ni composite coating shows the best tribological properties and its wear resistance is higher than that of theVIhigh-speed nickel electro brush plating coating and 1045 steel. Test results show that the sliding speed, normal load, sand conte
13、nt and size in the oil, surface condition and friction couple material influence the tribological behavior of the composite coating in abrasive contaminant condition. With the load, sand size and sand content increasing, the wear volume of the composite coating increases. With the sliding speed incr
14、easing, the wear volume increases first, but then decreases. The load and sande content show greater influence on the wear volume, while the sliding speed and sand size show greater influence on the friction coefficient. The main wear mechanism of the composite coating at low load and low speed is a
15、brasive wear, while, at high load and high speed is plastical deformation and adhesive wear. The wear volume for the coating un-polished and for the friction couple of the steel ball is 10 times higher than that for the coating polished and for the friction couple of the ceramic ball respectively. T
16、he coating of the high velocity arc sprayed 3Cr13 steel shows compact microstructure, smooth surface morphology, low porosity and high bond strength. The wear resistance of the coating in abrasive contaminant lubrication is 15% higher than that of the 38CrSi steel. The microsture and mechanical properties of the super-sonic plasma sprayed 12Co-WC coating is superior to that of the high velocity arc spraying coaitng. The decomposition of the WC is low, and the main phases in the coating are WC an
