海水工况下自润滑Fe基非晶/Si3N4复合涂层腐蚀和磨损交互行为研究

Many moving parts used in marine engineering equipment use seawater as the lubricant to save oil resources and avoid its leakage and flammability. However, the friction pair lubricated by seawater is corroded and worn seriously because of the corrosion, low viscosity and poor lubrication characteristics of seawater, which affects the normal operation of the equipment seriously. Thus, it is very important to design and develop new friction materials suitable for marine environment. In this project, Fe based amorphous/Si3N4 composite coating will be prepared, Fe based amorphous coating as the corrosion and wear resistant substrate, Si3N4 not only plays the strengthening and toughening effect, but also gives the coating self-lubrication function in seawater by reacting with seawater to form silica gel film as lubricant during friction process. The effect of doping and content of Si3N4 on the structure, hardness and toughness, especially the self-lubrication, corrosion and wear interaction behavior of the coating in seawater will be studied, in order to understand the dynamic evolution of the failure mechanism of the coating in seawater. The successful implementation of this project will not only provides a new design method for friction materials in marine environment, but also provides law for exploring the service behavior and corrosion-wear coupling effect of friction materials in marine environment.

海洋工程装备中的许多运动部件采用海水作为润滑介质，不仅节约资源，而且避免了润滑油的泄漏污染和易燃等弊端。然而，海水腐蚀性强、粘度低，润滑效果差，摩擦副材料存在腐蚀与磨损等问题，严重影响了运动部件的正常工作和使用寿命。设计开发适合海洋环境的新型摩擦副材料是亟待解决的重要课题。因此，本项目拟通过设计制备Fe基非晶/Si3N4复合涂层，利用Fe基非晶涂层耐腐蚀和耐磨损的特性，并发挥Si3N4对涂层的强韧化作用，以及Si3N4和海水发生摩擦反应生成硅胶膜发挥润滑作用的独特之处，赋予涂层海水中自润滑功能。研究Si3N4对涂层组织结构、硬度和韧性的影响，重点研究涂层在海水中的自润滑性能以及腐蚀与磨损交互行为，深入认识涂层在海水中摩擦失效时的动态演化机理。项目的实施不仅为海洋环境中服役的摩擦副材料提供了新的设计方法，也将为进一步探明摩擦副材料在海洋环境中的服役行为和腐蚀与磨损耦合作用规律提供理论依据。

Fe基非晶涂层具有优异的耐腐蚀和抗磨损性能，将成为石油化工、电力、汽车工业、核电、海洋等领域极具发展潜力的表面防护材料。本项目利用热喷涂技术制备Fe基非晶涂层以及非晶/Si3N4复合涂层，研究涂层的耐腐蚀和抗磨损性能。本项目主要进行了以下几方面的研究：(1) 结构弛豫和晶化对涂层耐腐蚀和抗磨损性能的影响。结构弛豫有助于缓解应力，减轻涂层的剥落，提高涂层的耐磨性。晶化后涂层中产生了碳化铬等脆性相，导致涂层脆性增加，在高载荷下的耐磨性明显下降。另外，结构弛豫有助于涂层微观结构的致密化和均匀化，在腐蚀溶液中形成稳定性更高的钝化膜，提高涂层的耐腐蚀性能；晶化后涂层中碳化铬等的生成导致产生贫Cr区，明显降低涂层的耐腐蚀性能。(2) 封孔处理对涂层耐腐蚀和抗磨损性能的影响。针对涂层中孔隙的影响，利用磷酸铝进行封孔处理。结果表明，在超声振动和真空热处理作用下，封孔剂渗透到涂层中180μm以上。封孔剂堵住电解液进入涂层的通路，涂层的腐蚀电位从-0.433提高到-0.262VSCE，腐蚀电流密度从2.99降低到6.75×10-2µA/cm2，钝化电流密度从44.66降低到1.32µA/cm2。显然，封孔处理提高了涂层的耐蚀性。此外，封孔处理抑制了涂层在摩擦过程中裂纹的萌生和扩展，减少剥落磨损，从而提高了涂层的耐磨性。(3)采用等离子喷涂技术制备了Fe基非晶/Si3N4复合涂层。结果表明，当Si3N4质量分数为10wt%时，复合涂层的耐磨性提高。此外，经磷酸铝封孔处理后，复合涂层的耐磨性进一步提高。磨损形貌表明，适量Si3N4的掺杂和封孔处理可以减缓剥落磨损，一定程度上提高涂层的耐磨性。相关工作针对Fe基非晶涂层性能的不足之处开展了相应的工作，在改善Fe基非晶涂层的耐腐蚀和抗磨损方面进行了探索，对推动Fe基非晶涂层在表面防护领域的应用具有参考价值。