强风沙尘环境下等离子喷涂复合层冲蚀及腐蚀磨损行为研究

Plasma spray technology has been successfully used in many industrial fields to protect enigineering components from wear, corrosion or heat. However, little has been involved in about the erosion-abrasion and corrosion-abrasion behaviors of the coatings under multiphase--flow condition such as great wind、severe sand storm and high salinity media,and so on. due to the coupling uncertainties of multiphase--flow hydrodynamics and corrosion kinetics, and difficulties of the porous coatings injury monitoring. This is very serious in Xinjiang due to its special environment. Combined with the environments of Xinjiang, the erosion- and corrosion-abrasion behaviors of the plasma spray composite coatings on metal were studied under the severe environment such as great wind and sand, and the serious corrosion, etc. Therefore, combined with numerical simulation,the multiphase-flow tests, i.e., the gas-sand, gas-sand-salt, and gas- or liquid-sand-salt , respectively, were employed to obtain the failure mechanism of the coatings under the complex actions of the erosion and corrosion of the wind，sand and salt. The response effectiveness of the erosion- and corrosion-abrasion behaviours of the coatings on its porous microstructure under different media condition were discovered.The relationship which reflect the composition, structure and configuration and its erosion- and corrosion-abrasion properties were built. The erosion- and corrosion-abrasion mechanism and matrix which reflect the running condition at the complicated working condition in Xinjiang were established. Based on the aforementioned results, the direction and probability aiming for improving the erosion- and corroison-abrasion resistance of the plasma spray coatings were put forward.

等离子喷涂技术已被广泛应用于防腐耐磨改性技术中，但由于流体动力学和腐蚀动力学耦合的不确定性以及对多孔涂层损伤监测的困难，有关涂层在强风、沙尘、高矿化度介质环境下的多相流冲蚀和腐蚀磨损行为的研究则很少涉及。由于新疆特殊的自然环境,对材料的冲蚀和腐蚀磨损问题十分突出。本项目结合新疆的自然环境，针对金属材料表面等离子喷涂复合层在高风沙、高腐蚀等恶劣环境下的冲蚀和腐蚀磨损行为展开研究。通过气-砂、气-砂-盐、气/液-砂-盐等多相流下冲蚀和腐蚀磨损试验，结合多相流数值模拟，获得在风沙盐冲蚀和腐蚀环境复合作用下涂层的冲蚀和腐蚀磨损失效行为规律；揭示不同介质环境下涂层冲蚀及腐蚀磨损行为对其多孔结构孔隙参量的响应效应，构建等离子喷涂复合涂层组成、结构和组态与其冲蚀及腐蚀磨损性能的关系；构建适合于新疆复杂工况下等离子喷涂复合层的多相流冲蚀磨损机理和模型；提出改善涂层冲蚀磨损抗力的方向和可能性。

由于各种机器零件在运转中的磨损以及机械构件在各种不同介质中工作的腐蚀，会使零部件表面性能和尺寸发生变化，并由此导致机器工作效率降低，甚至使整个设备丧失工作能力。对于新疆来说，这种情况尤为严重。本项目分析了喷涂电流、送粉速度、喷涂距离、粉末粒度等工艺参数对涂层组织结构、相组成、涂层厚度、孔隙参量（孔隙率和孔隙直径）、显微硬度、结合强度的影响规律，研究涂层组态（特别是孔隙参量）与残余应力对涂层硬度、结合强度的影响，建立定量描述涂层结构与性能之间的理论关系，阐明影响涂层性能的结构参数及其影响规律，为优化涂层性能提供依据。研究多相流流型和相态分布规律，建立流体动力学模型；研究磨损、腐蚀及其耦合作用在涂层不同微区损伤的贡献，分析冲蚀与腐蚀耦合破坏机制，建立冲蚀与腐蚀动力学模型。将数值模拟与试验相结合，构建等离子喷涂复合涂层组成、结构和组态与其冲蚀及腐蚀磨损性能的关系，阐明影响涂层性能的结构参数及其影响规律；构建适合于新疆复杂工况下涂层的冲蚀和腐蚀磨损机理和模型，完成涂层在一定介质环境下的失效预测；建立涂层的冲蚀或腐蚀磨损失效行为与其微结构特征和环境介质的对应关系；提出改善涂层冲蚀磨损抗力的方向和可能性。通过曲面响应法对影响涂层性能的因素进行分析，得到各影响因素的主次顺序以及各因素的交互式影响规律。利用基于回归分析的多目标参数优化和基于灰关联分析的多目标参数优化两种方法对喷涂工艺进行优化，获得所选参数条件下较好工艺参数，制备复合涂层。利用 SEM、EDS 和 XRD 等测试手段分析了涂层的微观形貌及物相、元素等组织成分，测试了涂层截面显微硬度和划痕附着强度。同时，探索了不同冲蚀角下(30°/60°/90°)涂层冲蚀磨损机理，在冲蚀角为 60°时涂层冲蚀磨损率最大。涂层截面显微硬度随距表面距离增大而逐渐变小，硬化层厚度大约为300μm，涂层硬度有一定的起伏。