清净剂、分散剂与ZDDP复配对a-C薄膜摩擦学性能的影响* |
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引用本文: | 张绍筠,岳文,王艳艳,黄海鹏,张广安. 清净剂、分散剂与ZDDP复配对a-C薄膜摩擦学性能的影响*[J]. 中国表面工程, 2023, 36(6): 90-99 |
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作者姓名: | 张绍筠 岳文 王艳艳 黄海鹏 张广安 |
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作者单位: | 中国地质大学(北京)工程技术学院 北京 100083;中国地质大学(北京)工程技术学院 北京 100083 ;中国地质大学(北京)郑州研究院 郑州 450001;中国地质大学(北京)工程技术学院 北京 100083 ;中国石化润滑油有限公司北京研究院 北京 100085;中国科学院兰州化学物理研究所 兰州 730000 |
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基金项目: | 国家自然科学基金资助项目(51875537) |
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摘 要: | 固-液复合润滑系统是获得高燃油经济性和高耐用性发动机系统的关键技术。极压抗磨剂二烷基二硫代磷酸锌(Zinc dialkyldithiophosphate, ZDDP)、清净剂高碱基磺酸钙(Over-base calcium sulfonate, OBCaSu)与分散剂聚异丁烯丁二酰亚胺 (Polyisobutylene succinimide, PIBSI)作为配方润滑油中使用最广泛的三种润滑油添加剂,与常用发动机表面强化薄膜类金刚石(Diamond-like carbon, DLC)薄膜复配下摩擦学性能的相关研究仍较少。利用非平衡磁控溅射方法制备 a-C 薄膜,通过 CSM 摩擦磨损试验机评价 ZDDP 与 OBCaSu(ZDDP+OBCaSu)、ZDDP 与 PIBSI(ZDDP+PIBSI)复配条件下 a-C 薄膜的摩擦学性能,并利用拉曼光谱、SEM 和 EDS 能谱等手段分析摩擦化学反应,探究摩擦机理。结果表明,ZDDP、ZDDP+OBCaSu 和 ZDDP+PIBSI 润滑三种润滑条件下,GCr15 钢和 a-C 薄膜磨损表面形成含磷酸盐的摩擦反应膜,两者摩擦学性能随润滑剂的变化规律相似。ZDDP+OBCaSu 复配润滑下,磨损表面形成的 Ca3(PO4)2 和 Zn3(PO4)2 复合摩擦反应膜可以提高 GCr15 钢和 a-C 薄膜的抗磨损性能。ZDDP+PIBSI 复配润滑下,GCr15 钢和 a-C 薄膜摩擦学性能下降。通过对比研究传统润滑油添加剂在 GCr15 钢和 a-C 薄膜表面的摩擦学行为和摩擦化学反应机理,为 a-C 薄膜在发动机系统中应用以及研发适配 a-C 薄膜的润滑油配方提供数据支持和理论指导。
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关 键 词: | 类金刚石(DLC)薄膜;油润滑;二烷基二硫代磷酸锌(ZDDP);摩擦;磨损 |
收稿时间: | 2022-12-29 |
修稿时间: | 2023-08-29 |
Effect of Detergent, Dispersant, and Zinc Dialkyldithiophosphate on the Tribological Properties of Amorphous-C Films |
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Abstract: | The solid-liquid composite lubrication system is a key technology for achieving high-fuel-economy and high-durability engine systems. Diamond-like carbon (DLC) films have high hardness, a low friction coefficient, and good biocompatibility, thereby being widely applied in engine system, involving valve lifters, piston rings, etc. It is well known that the performance of oil lubricants is highly correlated with the chemical composition of the grinding surface materials. Previous studies have shown that Fe2+ from ferrous materials directly takes part in the tribochemical reactions of oil lubricants. DLC films exhibit chemical inertness, in contrast to traditional ferrous materials. However, the current formulas for engine oil lubricants are universally developed for ferrous materials,and a special lubricant formula for DLC films needs urgent improvement. The extreme-pressure antiwear agent zinc dialkyldithiophosphate (ZDDP), the detergent calcium persulfonate (OBCaSu), and the dispersant polyisobutylene succinimide (PIBSI) are the most widely used additives in formulated lubricants. However, there is still limited research on the tribological properties of DLC films lubricated with the above additives. In this work, amorphous carbon (a-C) films were prepared via nonequilibrium magnetron sputtering, and the tribological properties of the a-C films under boundary lubrication conditions between ZDDP and OBCaSu (ZDDP+OBCaSu) and between ZDDP and PIBSI (ZDDP+PIBSI) were evaluated using a CSM tribometer. The tribochemical reactions were analyzed using Raman spectroscopy, scanning electron microscopy, and energy dispersive spectroscopy (EDS), combined with the full formula (FF) oil and GCr15 steel, to explore the tribological mechanism of a-C films. The morphologies of worn surfaces were determined with a three-dimensional surface profilometer, and it can be seen that the main wear mechanism of a-C films against steel balls is abrasive wear. Under various lubrication conditions, the results indicate that the worn surfaces of the a-C films undergo graphitization compared to the unworn surfaces, which is beneficial for achieving a low friction coefficient. Phosphate tribofilms are formed on the worn surfaces of GCr15 steel and a-C films under ZDDP, ZDDP+OBCaSu, and ZDDP+PIBSI lubrication conditions. Under a ZDDP+OBCaSu lubrication condition, the composite tribofilms of Ca3(PO4)2 and Zn3(PO4)2 on the worn surfaces of GCr15 steel and a-C films can improve their wear resistance and lubrication performance, which was confirmed by the low friction coefficients and wear rates. Moreover, similar friction coefficients and wear rates on the surfaces of GCr15 steel and a-C films are obtained. Therefore, the tribochemical reaction of the ZDDP+OBCaSu lubrication has less dependence on the surface materials. Under ZDDP+PIBSI lubrication, the tribological properties of GCr15 steel and a-C films decrease, resulting in high friction coefficients and high wear rates. According to the EDS energy spectrum, it can be derived that the strong dispersion of PIBSI is not conducive to the formation of phosphate tribofilms. Under FF lubrication conditions, the tribological properties of GCr15 steel and a-C films decreased compared to those under ZDDP, ZDDP+OBCaSu, and ZDDP+PIBSI lubrication conditions, which may be influenced by the lubricant concentrations and other lubricants. In this work, the tribological behavior and tribochemical reaction mechanism of traditional oil lubricants on the surfaces of GCr15 steel and a-C films are studied. Overall, the results show that the changes in the friction coefficients and wear rates of GCr15 steel and a-C films with various lubricants are similar. However, the a-C films are not sensitive to the lubricants. That is, compared to GCr15 steel, the tribological performance of the a-C films under different lubricants fluctuates by only a minor degree. Therefore, there is a need to develop more suitable oil lubricant formulas for a-C films. This work serves as a guidance for future design and development of lubricants and a-C films for energy savings and fuel efficiency. |
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