ISSN   1004-0595

CN  62-1224/O4

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亲水分子修饰炭纳米片的制备及其水基润滑性能研究

Preparation of Carbon Nanosheets Modified with Hydrophilic Molecules and the Corresponding Research on Influence Factors of Hydration Lubrication

  • 摘要: 传统油基润滑剂在重型机械的相互作用体系中发挥着重要的作用,助力工业时代的快速发展,但随着对材料的绿色环保性需求与日俱增以及润滑体系使用场景的不断丰富,安全、环保且价格低廉的水基润滑体系正势不可挡地占据着越来越重要的地位,水基润滑添加剂是这个体系中至关重要的组成部分. 本文中通过碳化配位聚合物制备富含氮原子掺杂的炭纳米片,以此为基底,以贻贝仿生的“黏性”物质聚多巴胺为媒介,借助迈克尔加成反应分别将带有正电、负电和两性离子基团的亲水小分子化学锚固于炭纳米片表面,得到了3种水基润滑添加剂,而后研究其摩擦性能并通过多项理化表征探究其水基润滑机制与影响因素. 试验表明:得益于带电基团更强的水合能力,3种亲水小分子修饰均能有效提升水基润滑剂的减摩抗磨性能,其中,修饰负电性丙烯酸酯磺酸盐的炭纳米片(SPMA-PCNS)表现出最佳的润滑效果,其表现出的性能优越性可归因于2个方面:SPMA的迈克尔加成活性高,高的SPMA接枝量带来更丰富的水合作用,水合层会带来更好的边界润滑效果;其次,SPMA-PCNS表面呈负电性,利于其在铁基摩擦副表面的吸附与反应,形成坚固的摩擦保护膜. 进一步对磨斑表面分析,发现SPMA-PCNS会在摩擦热和机械力的作用下与钢基质发生摩擦化学反应,生成以碳氮化物、铁硫化物和铁氧化物为主的摩擦反应膜,与水合作用带来的边界润滑层协同作用共同保护摩擦副表面,有效减少摩擦磨损. 本研究为制备水基润滑添加剂提供了可行的修饰思路,且揭示了水基润滑影响因素,有助于设计高性能水基润滑添加剂和理解摩擦机理.

     

    Abstract: Traditionnal oil-based lubricants play significant role in interaction systems of heavy duty machaniery, which has propelled the rapid development of industrial age. Nevertheless, with the increasing demand in environmental friendiness of materials, as well as the continuous enrichment of lubrication systems in using scenarios, safe, envirornmentally-friendly and inexpennsive water-based lubriants is inexorably occupying more and more important position, in which the water-based lubricant additives compose a vital part. In this paper, carbon nanosheets abound with doped N atoms were fabricated by means of carbonizing coordination polymers, based on which mussel-inspired “sticky” poly-dopamine was taken as intermediary, creating environment for hydrophilic molecules with electropositive, electronegative, zwitterionic groups covalently anchored into the surface of carbon nanosheets via Michael addition reaction. Thus three water-based lubricant additives were obtained to investigate their tribological performance and accordingly dig out the water-based lubrication mechanism as well as influence factors via various physicochemical characterizations. It was found in experiments that all the modifications were able to enhance the anti-frcition and anti-wear performance of hybrid lubricity efficiently due to the stronger hydration ability of charged groups, among which the carbon nanosheets modified with electronegative acrylate sulfonates (SPMA-PCNS) exhibited the most enhancement effect, the outstanding superiority in tribological performance of which could be attributed to two aspects: on the one hand, SPMA possessed the highest acitivity of Michael addition reaction, resulting in the most grafting amount, which brought sufficient hydration and the thicker hydration layer acted on better effect on boundary lubrication, on the other hand, the surface of SPMA-PCNS presented to be eletronegative, which was conducive to the adsorption and tribo-reaction between the additives and tribo-pairs, and hence a robust protective tribo-film was able to form. Further analysis into wear scar revealed that SPMA-PCNS was capable of reacting with steel substrate during friction under the action of friction heat and mechanical force, as a consequence, a tribo-film composed of carbon nitride, iron sulfide and iron oxides was formed, which played a synergistic effects with the boundary lubrication layer by hydartion to protect the surface of tribo-pairs, meanwhile, reduce the friction and wear efficiently. This research provided a feasible idea in preparation and modification of water-based lubricant nanoadditives, in the meanwhile, it revealled the potential influence factors of water-based lubrication, which contributed to the design of lubricant additives with high performance and the understanding of lubrication mechanism respectively.

     

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