Preparation Of CuNi Alloy Coating Based Bare Cu And Investigation Of The Corrosion Properties

Copper(Cu) metal is a kind of engineering materials used in many fields because of its good conductivity, thermal conductivity, and chemical stability in the modern industry. Although there is a large hardness may be desirable in certain special field like ocean environment. This widely used copper metal is subject to amount of chlorine erosion in seawater. And copper metal is inevitable to suffer from strong corrosion. So the application of copper in Marine engineering is limited and it is difficult to be further applications. Copper-nickel (CuNi) alloys are having an important role in the field of Marine engineering owing to its outstanding properties especially the excellent corrosion resistance. Nickel, as an essential engineering material, has excellent corrosion resistance. The excessive introduction of nickel element in copper- formed the copper-nickel alloy result in an increase in the cost. At the same time, most of the production process of CuNi alloys must overcome the complex preparation equipment and the serious operating environment. The electrodeposition of CuNi alloys has been extensively investigated due to interest in their properties. It can consist of rather simple and cost-effective equipment that overcomes the weakness of the high vacuum and the high temperature. The sample is obtained by a high efficiency. And the other hand, the electrodeposition can achieve accurate proportion of the alloy composition If get the CuNi alloy nanocrystalline layer in pure copper surface, it will improve significantly properties and application of pure copper, especially corrosion resistance, and save economic cost. The pure copper will get boarder application in the Marine engineering. In this paper, the different content CuNi alloy film layers are prepared in the pure copper surface by electrodeposition which uses as the most experimental method that in order to obtain the surface of pure copper with alloy layer materials. Then the heat treatment method is adopted in the late processing of the CuNi alloy which is expected to improve the quality of the alloy film layer and further corrosion resistance through adjusting experimental parameters with the help of the measurement and characterization.The complexing ability of mainly two complexing agents are discussed in the first of the paper. The cyclic voltammo grams testing (CV) is performed to predict the electrodeposition potential and electrodeposition current of CuNi alloys. Under the different electrodeposition potential the experimental results show that the growth model of CuNi alloys is three-dimensional instantaneous nucleation growth mechanism. The X ray diffraction (XRD) test shows that the different composition CuNi alloys are successfully prepared under the different electrodeposition current. By scanning electron microscopy (SEM), copper nickel alloy particles are nano-scale and packet tightly, some poles produces on the coating surface when the electrodeposition current is-25mA/cm2. Electrochemial testes suggest that CuNi alloy shows better corrosion resistance and the charge transfer blocking ability than the bare copper. Energy spectrometer (EDS) test obtains different CuNi content. When the nickel content is about 30% and the electrodeposition current is-15mA/cm2 which shows the best comprehensibe performance.The prepared CuNi alloys are carried out the hosting heat treatment in the nitrogen atmosphere. The SEM test shows the surface morphology with 300degree heat treatment that is clusters of body. A lot of small particles begin to accumulation together to form large particles. There is no accumulation of small particles mingled with the different clusters. Electrochemical test characterization of different heat treatment temperature shows that the CuNi alloy obtains the best corrosion resistance and the charge transfer blocking than the CuNi alloy without heat treatment and bare copper below 100degree heat treatment in the 3.5wt% NaCl solution simulated seawater. When the heat treatment is up to 200degree, the electrochemical properties is no further increase, which keep basic maintain with the CuNi alloy without heat treatment. But the heat treatment temperature continue to’increase, the electrochemical properties decline sharply, the corrosion resistance even lower than the bare copper. CV results in 30cycles demonstrate that the stability of CuNi alloy with heat treatment reduces that maybe the main reason for the decline in the anticorrosion performance.Finally the article explores the corrosion situation of the CuNi alloys under the different processing means. The CuNi alloys are more sensitive to the temperature than the bare Cu. The electrochemical measurement shows that high temperature corrosion resistance of CuNi alloy decrease sharply than the bare Cu. The high temperature corrosion resistance of CuNi alloy can increase to a certain extent when the surface coatings on the bare Cu go through the heat treatment.This paper discusses preliminarily the preparation condition of CuNi alloy by the electrodepositon technique. In the end of the paper, the paper explores the heat treatment parameters to optimize the experiment. The analysis of the electrochemical data revealed that there is a better corrosion resistance than the bare Cu. If combined the further explore and optimization, this preparation method and process of CuNi alloys will get more exciting application in the field of Marine engineering.