ISSN   1004-0595

CN  62-1224/O4

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余瑞, 来冰冰, 刘焕晨, 张利, 王晓波, 娄文静, 张晟卯. 含ZDDP锂基润滑脂摩擦学性能和润滑机理研究[J]. 摩擦学学报(中英文), 2024, 44(10): 1−13. doi: 10.16078/j.tribology.2023169
引用本文: 余瑞, 来冰冰, 刘焕晨, 张利, 王晓波, 娄文静, 张晟卯. 含ZDDP锂基润滑脂摩擦学性能和润滑机理研究[J]. 摩擦学学报(中英文), 2024, 44(10): 1−13. doi: 10.16078/j.tribology.2023169
YU Rui, LAI Bingbing, LIU Huanchen, ZHANG Li, WANG Xiaobo, LOU Wenjing, ZHANG Shengmao. Tribological Properties and Lubrication Mechanism of Lithium Greases Containing ZDDP Additives[J]. Tribology, 2024, 44(10): 1−13. doi: 10.16078/j.tribology.2023169
Citation: YU Rui, LAI Bingbing, LIU Huanchen, ZHANG Li, WANG Xiaobo, LOU Wenjing, ZHANG Shengmao. Tribological Properties and Lubrication Mechanism of Lithium Greases Containing ZDDP Additives[J]. Tribology, 2024, 44(10): 1−13. doi: 10.16078/j.tribology.2023169

含ZDDP锂基润滑脂摩擦学性能和润滑机理研究

Tribological Properties and Lubrication Mechanism of Lithium Greases Containing ZDDP Additives

  • 摘要: ZDDP (二烷基二硫代磷酸锌)作为润滑脂中常见的极压抗磨剂,其在润滑脂中的润滑机理一直是研究的重点和难点. 选用4种不同碳链长度的ZDDP (二丁基二硫代磷酸锌、二庚基二硫代磷酸锌、二辛基二硫代磷酸锌和二丁辛基二硫代磷酸锌)作为润滑脂添加剂,采用SRV摩擦磨损试验机对润滑脂体系的摩擦学性能进行评价,系统性考察了在不同运行工况(温度、载荷和频率)下,含不同碳链长度ZDDP的润滑脂体系的摩擦学性能及在往复滑动条件下ZDDP在润滑脂中成膜机理. 研究结果表明,ZDDP能提高基础脂的减摩抗磨性能;频率、载荷和温度对含ZDDP的润滑脂的减摩抗磨性能均有影响,其中温度对其影响最为关键. 对于含不同碳链长度的ZDDP润滑脂:在脂润滑状态下ZDDP的极压性能随着烷基碳链长度的增加而降低;在多数工况条件下含不同碳链长度ZDDP润滑脂体系摩擦学性能差别较小. 在往复纯滑动条件下摩擦膜生长过程:试球表面的摩擦膜随摩擦时间变化,初期摩擦膜薄且均匀,随后出现一些固体小颗粒,小颗粒不断积累演变成疏松的摩擦膜,经过长时间的摩擦形成致密的摩擦膜.

     

    Abstract: The lubrication mechanism of ZDDPs (zinc dialkyldithiophosphates) as a kind of common extreme pressure anti-wear agents in greases has been the focus and difficulty of research. Four types of ZDDPs (zinc dibutyl dithiophosphate, zinc diheptyldithiophosphate, zinc dioctyl dithiophosphate and zinc dibutyl octyl dithiophosphate) with different carbon chain lengths were selected as grease additives. By using SRV friction and wear testing machine, SEM and XPS, their tribological properties under different operating conditions (temperature, load and frequency) and the film formation mechanism of ZDDP in greases under reciprocating sliding conditions were systematically investigated. The upper test ball was made of AISI 52100 steel, φ10 mm, with a hardness of about 730 HV, and the lower test disc was made of AISI 52100 steel, φ24 mm×7.5 mm, with the same hardness of about 730 HV and a roughness less than 0.084 μm. The three-dimensional profile instrument was utilized to observe the wear morphology of the test discs and to calculate the wear volume. The base grease used in this experiment was the lithium grease, and the base oil was PAO8 (the base oil had a kinetic viscosity of 8 mm2/s at 100 ℃). The results showed that the additive of ZDDPs could improve the friction reduction and anti-wear properties of the base grease. Frequency, load and temperature had an effect on the friction reduction and anti-wear performances of greases containing ZDDPs, and the influence of temperature was particularly. The harsher the operating conditions (high-frequency, high-load, high-temperature) were the better friction reduction and anti-wear abilities of greases with containing ZDDPs were. The reason for this may be that the more intense friction produces more frictional heat, the more conducive to the growth of the friction tribofilm. For ZDDP greases with different carbon chain lengths, the extreme pressure performance of ZDDP decreased with the increasing of alkyl carbon chain length under grease lubrication. Their tribological properties showed difference under most operating conditions. Based on these above results, the improvement of the anti-friction and anti-wear properties of the greases containing ZDDPs was mainly due to the growth and formation of friction chemical films. During the reciprocating sliding conditions, the friction film growth process had been observed by SEM, and the abrasion surfaces from the upper test ball at different test times were analyzed by XPS and EDS. The test results showed that the friction film morphologies on the ball surface varied with the friction time. In the reciprocating sliding conditions of the friction film growth process, the initial friction film was thin and uniform, then followed by the emergence of a number of small solid particles. With the increasing of the operating time, the accumulation of small particles evolved into a loose friction film, which would be transformed to the dense friction film after a long time. Combined with the elemental analysis results of EDS, it was assumed that the deposition or reaction of sulfur elements to form lubricant film mainly occurred in the early stage, while the deposition or reaction of phosphorus and zinc elements continued throughout the entire operation process. This paper was of reference significance for the tribological researches of ZDDP-containing greases under reciprocating sliding conditions, and provided theoretical support for ZDDP to improve the friction reduction and anti-wear performance of greases.

     

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