等离子喷涂镍基复合涂层的微观结构及摩擦学行为研究

发布时间：2018-06-21 18:38

本文选题：等离子喷涂 + 镍基复合涂层　；参考：《重庆理工大学》2015年硕士论文

【摘要】：等离子喷涂技术作为一种重要的表面改性技术,在汽车、航空、航天等领域的耐磨、耐腐蚀改性处理方面获得了广泛的应用。此外金属基复合材料因其高韧性和塑性以及其他材料的一些优异性能如高硬度等而大量应用于工业各领域,因此采用等离子喷涂技术制备的金属基复合涂层具有比单一材料更加优异的力学性能和机械性能等,能够满足材料日益发展的需求。采用等离子喷涂技术制备镍基复合涂层,选择镍基合金(Ni60AA粉末)为基体相,添加碳化钨粉末(WC-12%Co粉末)为增强相以改善镍基涂层相对于其它一些材料的低硬度和耐磨损问题。结果表明：热喷涂镍基复合涂层的物相组成相比原始粉末未发生显著变化,均由镍固溶体相和WC增强相所组成；微观结构分析显示镍基涂层为典型的层状结构,涂层气孔率降低,添加的WC增强相成带状分布,表明易于变形的团聚WC颗粒改善了镍基合金涂层的喷涂性能。制备并考察了WC增强相对镍基复合涂层力学性能的影响,结果表明：WC增强相显著提高了镍基复合涂层的硬度,但是造成涂层弹性模量的下降,进而硬模比随WC增强相含量的增大而增大。研究了镍基复合涂层在仿发动机运行工况下(油润滑、贫油润滑、干摩擦)的摩擦磨损行为及机理,结果表明：直接喷涂于铝基体的镍基复合涂层显著改善了铝合金材料的耐磨损性能,尤其是贫油润滑和干摩擦条件下摩擦磨损性能,可大大提高发动机缸体的运行寿命;此外制备的喷涂涂层中存在着一定的空隙,在摩擦磨损的过程中这些空隙可以起到暂时储存颗粒以及储油的功能,这对于改善涂层的摩擦性能起到了至关重要的作用。随后WC增强相的加入则进一步降低了体系的磨损率,提高铝合金涂层材料的高耐磨,有望替代镶嵌铸铁缸套。研究了镍基复合涂层在海洋工况下(海水润滑、纯水润滑、干摩擦)的腐蚀磨损行为机理,结果表明：镍基复合涂层改善了316L不锈钢的腐蚀摩擦性能,通过对镍基复合涂层和不锈钢基体在人工海水溶液中磨损腐蚀性能实验的结果分析,可以看出镍基复合涂层相对于不锈钢表现出的优异的耐磨损腐蚀性能,因此,镍基复合涂层可用于不锈钢材料的表面强化,改善海洋工况下运转部件的耐磨蚀性能。
[Abstract]:As an important surface modification technology, plasma spraying technology has been widely used in the fields of automobile, aviation, aerospace and so on. In addition, metal matrix composites are widely used in various fields of industry because of their high toughness and plasticity, as well as some excellent properties of other materials, such as high hardness. Therefore, the metal-based composite coatings prepared by plasma spraying technology have better mechanical and mechanical properties than single materials, and can meet the growing needs of materials. The Ni-base composite coating was prepared by plasma spraying. The Ni-base alloy (Ni60AA powder) was selected as the matrix phase and the tungsten carbide powder (WC-12Co powder) was added as the reinforcing phase to improve the low hardness and wear resistance of the Ni-based coating compared with some other materials. The results show that the phase composition of thermal sprayed nickel-base composite coating is not significantly changed compared with the original powder, and all of them are composed of nickel solid solution phase and WC reinforced phase, and the microstructure analysis shows that the nickel based composite coating is a typical layered structure. The porosity of the coating decreased, and the WC reinforced and formed a zonal distribution, which indicated that the agglomerated WC particles, which were easy to deform, improved the spraying properties of the Ni-base alloy coating. The effect of WC reinforcement on the mechanical properties of Ni based composite coatings was investigated. The results showed that the hardness of Ni based composite coatings was significantly increased by the W WC reinforcement phase, but the elastic modulus of the coatings decreased. Furthermore, the ratio of hard to die increases with the increase of WC reinforcement phase content. The friction and wear behavior and mechanism of Ni-based composite coatings under engine operating conditions (oil lubrication, lean oil lubrication, dry friction) were studied. The results show that the Ni-based composite coating directly sprayed on aluminum substrates can significantly improve the wear resistance of aluminum alloy materials, especially under the condition of lean oil lubrication and dry friction, and can greatly improve the running life of engine cylinder block. In addition, there are some voids in the sprayed coatings, which can store particles and oil temporarily in the process of friction and wear, which plays an important role in improving the friction properties of the coatings. The addition of WC reinforcements further reduces the wear rate of the system and improves the wear resistance of aluminum alloy coating materials, which is expected to replace the inlaid cast iron cylinder liner. The corrosion and wear behaviors of nickel based composite coatings under sea conditions (seawater lubrication, pure water lubrication, dry friction) were studied. The results showed that the corrosion and friction properties of 316L stainless steel were improved by nickel based composite coatings. Through the analysis of the wear and corrosion performance of nickel based composite coating and stainless steel substrate in artificial sea aqueous solution, it can be seen that the nickel base composite coating has excellent wear and corrosion resistance compared with stainless steel. Therefore, the wear and corrosion resistance of nickel based composite coating is better than that of stainless steel. Nickel-based composite coating can be used to strengthen the surface of stainless steel and improve the wear and corrosion performance of operating parts under marine conditions.
【学位授予单位】：重庆理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG174.4

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