农业工程学报Issue(15)：54-61,8.DOI:10.3969/j.issn.1002-6819.2014.15.008
发动机气缸电喷镀镍磷合金镀层及耐腐蚀性能
Anti-corrosion properties of Ni-P alloy coated on engine cylinder prepared from jet electrodeposion
摘要
Abstract
Cylinder is the important part of tractor engine, which service life and the production cost are directly affected by anti-corrosion of the component. With the excellent wear resistance, corrosion resistance and higher hardness, Ni-P alloy deposited layer plays an important role for enhance the service life and reliability of cylinder, and the capability and quality of the tractor engine can be improved. Because of severe working environment of cylinder and piston such as high temperature, high load, high-velocity motion, poor lubrication, difficult cooling, especially weak acid for work environment, it is advisable to study the anti-corrosion properties of Ni-P alloy coated on engine cylinder. However, with the advancement of social economy, the conventional method for electrodeposited Ni-P alloy fails to meet the requirements of the development due to lower depositing rate and lower production efficiency. The jet electrodeposition is developed in recent years, which can significant increase the production efficiency because jet electrolyte can accelerate transfer process of the electrodeposition material and augment limiting current density. So the jet electrodeposition is a kind of high-velocity, selective electrodeposition technique with high deposition current density. In this paper, the engine cylinder coated with Ni-P alloy with jet electrodeposition was taken as research object. The surface appearance of deposited layer was observed by 6XB-PC reflective optical microscope. The corrosion behavior of Ni-P alloy coated on cylinder in 50 g/L NaCl solutions at different moment was studied by electrochemical impedance spectroscopy and potentiodynamic polarization method. The results show that the coating surface appearance is dense and smooth. Electrochemical impedance spectroscopy is composed of high and low frequency arcs when the layer immersed in 50 g/L NaCl solutions with 0.5, 1, 6, 12 and 24 h. The high frequency arcs have relation with original oxidation film, and the low frequency arcs have relation with corrosion process of electrode. While the layer is immersed in 50 g/L NaCl solutions 48 and 72 h, the electrochemical impedance spectroscopy is composed of high, medium and low frequency capacitive reactance arcs. The corrosion resistance of Ni-P alloy coating has the trend of decrease and then increase with the immersion time duration. At first, the thickness of oxide layer is thinned in 50 g/L NaCl solutions due to the attack of Cl-. After oxide layer by Cl-penetration, Ni-P alloy will begin to dissolve. And then, the corrosion products are generated and gather on Ni-P alloy, which prevent the process of corrosion. The whole corrosion processes changed from activation control into diffusion control of Ni-P alloy coating and corrosion products. The corrosion resistance of Ni-P coating obtained by jet electrodeposition is about 5 times to traditional electrodeposition. Obviously, Ni-P alloy coating prepared from jet electrodeposition has excellent corrosion resistance. The study can provide a reference for improving the anti-corrosion properties of Ni-P alloy coated on engine cylinder with jet electrodeposion.关键词
发动机/耐腐蚀性/交流阻抗谱/极化曲线/电喷镀Key words
engines/corrosion resistance/electrochemical impedance spectroscopy/polarization curve/jet electrodeposion分类
农业科技引用本文复制引用
王颖,康敏,傅秀清,王兴盛..发动机气缸电喷镀镍磷合金镀层及耐腐蚀性能[J].农业工程学报,2014,(15):54-61,8.基金项目
江苏省普通高校研究生科研创新计划资助项目（CXZZ12_0271）；南京农业大学工学院引进人才科研启动基金项目 （）
