ISSN   1004-0595

CN  62-1224/O4

高级检索

缓蚀型润滑防腐功能涂层的制备及防护机制研究

Preparation and Protection Mechanism of Anticorrosive Lubricating Coatings

  • 摘要: 磨损与腐蚀的耦合作用会加剧高端装备关键运动部件的损伤失效,导致其服役寿命大幅缩减. 本文中基于铬酸锶(SrCrO4)的缓蚀特性及聚四氟乙烯(PTFE)的低表面能和低剪切特性,结合综合性能优异的酚醛环氧树脂制备了兼具良好耐腐蚀和摩擦学性能的铬酸锶/聚四氟乙烯/酚醛环氧(SrCrO4/PTFE/EPN)功能一体化复合涂层. 采用摩擦磨损试验、电化学阻抗谱和极化曲线研究了SrCrO4、PTFE及腐蚀摩擦介质对复合涂层的摩擦学性能和抗电化学腐蚀性能的影响,重点研究了SrCrO4在酚醛环氧涂层中的缓蚀防护机理. 结果表明:SrCrO4缓蚀作用下基材界面发生化学反应,产生了缓蚀钝化层,能够有效提高涂层的耐腐蚀性能. 尤其SrCrO4添加量为树脂质量的4%时,钝化效果最佳,低频阻抗模量值和腐蚀电流密度分别为1.06×1011 Ω∙cm 2和0.28×10−10 A/cm2;PTFE的引入不仅将涂层由亲水性转变为疏水性,进一步提升了涂层的屏蔽阻隔特性,使涂层被电解质溶液浸入的时间滞后了10倍,而且使涂层的摩擦学性能明显提升,相较酚醛环氧涂层摩擦系数降低约73.90%,耐磨损性能提高3.2倍;在质量分数为3.5% NaCl溶液的腐蚀介质条件下,SrCrO4/PTFE/EPN复合涂层表现出更低的摩擦系数,且能够在摩擦副接触界面形成钝化防护膜,该钝化膜主要以Fe和Cr氧化物、氢氧化物或结晶水化物的形式存在,从而有效抑制对偶面由于腐蚀而产生的磨损.

     

    Abstract: The coupling effect of wear and corrosion intensifies the damage and failure of key moving parts of high-end equipment, leading to a significant reduction in their service life. It is expected to solve the above problems by introducing the anticorrosive filler and solid lubricant into the polymer binder to prepare the protective coating. However, at present, most researches on organic bonded coatings with corrosion inhibition performance focus on the corrosion resistance of coatings, while the influence of corrosion inhibitors on the tribological properties of coatings is not clear, and organic bonded coatings with corrosion inhibition and excellent tribological properties are rarely reported. At present, among the corrosion inhibitors used for organic coatings, chromate is the most effective and widely used, among which strontium chromate (SrCrO4) shows good compatibility, and its solubility is low and there is still enough dissolution to ensure its corrosion inhibition. Based on the corrosion inhibition characteristics of SrCrO4 and the low surface energy and low shear characteristics of polytetrafluoroethylene (PTFE), the functional integrated strontium chromate/ polytetrafluoroethylene/phenolic epoxy (SrCrO4/PTFE/EPN) coatings with excellent corrosion resistance and tribological properties were prepared. The effects of SrCrO4, PTFE and corrosion friction medium on tribological properties and electrochemical corrosion resistance of coatings were investigated by CSM friction and wear testing machine and P4000A electrochemical workstation. In order to focus on the corrosion inhibition and protection mechanism of SrCrO4 in phenolic epoxy coating, we firstly introduced SrCrO4 into EPN coating, and studied the surface morphology and electrochemical corrosion resistance of the coating. It was found that, especially when the introduction amount of SrCrO4 was 4% of the resin mass, the surface of the coating was flat and compact with no obvious pores. SrCrO4 introduced can be uniformly embedded into the coating, and fill the intrinsic defects of the coating, which can improve the barrier performance of the coating, and can chemically react with the substrate to produce a uniform and stable passivation film at the interface. Similarly, the passivation effect was the best when the added amount was 4% of the resin mass. It presented A high low-frequency impedance modulus (1.06×1011 Ω∙cm 2) and the lowest corrosion current density (0.28×10−10 A/cm2), which effectively improved the corrosion resistance of the coating and had little influence on the tribological properties of the coating. The surface energy of SrCrO4/EPN coating was decreased by adding PTFE, and the water contact angle of the coating increased by 31% from 73.4° to 96.0°, which made the coating change from hydrophilic to hydrophobic, and further increased the barrier property of the coating. The corrosion resistance and tribological properties of SrCrO4/PTFE/EPN coating were further investigated. The results showed that SrCrO4 can still react on the substrate interface through corrosion inhibition, resulting in a corrosion inhibition passivation layer, which can effectively improve the corrosion resistance of the coating. The introduction of PTFE not only further improved the shielding properties of the coating, but also significantly reduced the friction coefficient and wear rate of the coating. The friction coefficient was as low as 0.059, which was reduced by 73.90% compared with the pure EPN coating, and the wear resistance was increased by 3.2 times. Under the corrosive medium condition of 3.5% NaCl solution, SrCrO4/PTFE/EPN coating exhibits lower friction coefficient, and SrCrO4 in the coating can provide passivation protection for the friction pair. Passivation film in the form of Fe and Cr oxide hydroxide or crystallization hydrate is formed on the friction dual surface through passivation reaction. Thus, the wear intensification caused by the corrosion of friction pair is inhibited.

     

/

返回文章
返回