CAJ | 학술논문

为提高发动机气缸的耐久性，该文采用喷射电沉积法在发动机气缸上制备Ni-P合金镀层，并用电化学极化曲线方法和交流阻抗技术对比研究镀有Ni-P合金的发动机气缸在50 g/L的NaCl溶液中不同时刻的腐蚀规律和腐蚀机理。结果表明，随着浸泡时间的增加，原始氧化膜减薄，膜层下的Ni-P合金暴露在溶液中产生活性溶解，随后电极表面有腐蚀产物聚集，阻碍腐蚀的进行；腐蚀过程由活化控制转变为镀层和腐蚀产物内的扩散控制；电喷镀所得Ni-P镀层在NaCl溶液中的耐腐蚀性能约是传统电沉积的5倍左右，发动机气缸电喷镀Ni-P合金镀层后具有良好的耐蚀性。研究结果可为进一步提高镍磷镀层的耐腐蚀性能提供参考。
위제고발동궤기항적내구성，해문채용분사전침적법재발동궤기항상제비Ni-P합금도층，병용전화학겁화곡선방법화교류조항기술대비연구도유Ni-P합금적발동궤기항재50 g/L적NaCl용액중불동시각적부식규률화부식궤리。결과표명，수착침포시간적증가，원시양화막감박，막층하적Ni-P합금폭로재용액중산생활성용해，수후전겁표면유부식산물취집，조애부식적진행；부식과정유활화공제전변위도층화부식산물내적확산공제；전분도소득Ni-P도층재NaCl용액중적내부식성능약시전통전침적적5배좌우，발동궤기항전분도Ni-P합금도층후구유량호적내식성。연구결과가위진일보제고얼린도층적내부식성능제공삼고。
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.