Zinc nickel alloy electroplating is a new electroplating technology. The coating is no longer a simple zinc layer, but a zinc nickel alloy layer, which is plated on the steel surface.

A zinc alloy used as a steel alloy. ZN-2% Ni alloy is usually melted into ZN-2% Ni alloy. ZN-2% Ni alloy is used as zinc plating solution with nickel content of 0.04%? 0.09%. Compared with the traditional zinc coating, it can effectively solve the problem of thick steel coating, reduce the cost and improve the corrosion resistance of the coating.

The internal quality control of zinc nickel alloy electroplating is mainly to control the proportion of zinc and nickel in zinc plating, so that the nickel content in the coating reaches a certain content. To achieve this, the key is to control the proportion of zinc and nickel anode area and control the size of current (with analytical means to master the concentration of zinc and nickel). The appearance quality mainly depends on the quality of zinc plating brightener.

Background of zinc nickel alloy electroplating development in the bay:

Zinc alloys are zinc cobalt, zinc iron, zinc and nickel. The nickel alloy coating has the highest corrosion resistance of 90% of zinc. This alloy has been used in many parts of the world for many years. For example, galvanized nickel alloy sheets have provided excellent rough production in the automotive and computer industries, greatly improving corrosion resistance. Zinc nickel alloy electroplating of gasoline parts such as fuel pipe, actuator and transmission parts in Europe and America has been more standardized in Japan.

C. Development of Zn Ni alloy electroplating in China

(1) In 1988, Xia Zhenhua in high concentration nickel chloride and zinc sulfate acetic acid type zinc nickel alloy plating solution was bright and fine coating in higher dkl5? 30A / DM2 electroplating solution.

In 1993, Yang Fangzu and Xu Shukai of Xiamen University added bright zinc nickel (5%? 10% nickel) alloy coating into alkaline zinc nickel electroplating bath containing lead die and aa-1 additives. (1) In March 1992, Yuan Guowei of Guangzhou shuangguang college proposed that the zinc chloride coating with uniform luster in the chlorination bath has good appearance and corrosion resistance after blue passivation.

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(2) In 1993, Lu Anmin of Guangzhou jindianchuang Technology Co., Ltd. passed the test of micro acid and alkaline zinc nickel alloy electroplating and conversion film. Its corrosion resistance was more than five times higher than that of zinc, and more than three times of cadmium was zinc nickel alloy coating. The passivation film was bright five colors, military green and black D93.

(3) In June 1992, Zhu Liqun and Luo Dili of Beijing University of Aeronautics and Astronautics studied the corrosion resistance of zinc nickel alloy coating coated with organic coating in 5% sodium chloride solution and hydrochloric acid acid mist. The corrosion resistance of nickel alloy coating containing 10%? 15% nickel is the best.

(4) In June 1997, the preparation method of zinc chloride alloy coating was discussed. Abnormal codeposition and normal codeposition of Zn Ni alloy were discussed in 1998.

(5) 721-3 additive was used in chlorination bath, and zq1 was used in alkaline electroplating solution.

(6) In September 1997, Du Weiyi and Li Yi (South China University of Technology) studied the synthesis of TD additive for alkaline electroplating of bright zinc nickel alloy, and obtained high corrosion resistance of nickel 12.2%? 13% zinc nickel alloy coating. (7) Xu Jianchun and others (Shanghai Institute of light industry) have successfully developed the continuous coating of semi bright zinc nickel alloy electroplating additive nz-a.

(8) In 1996, Lu Jintang (South China University of Technology) and others studied the use of ammonia as complexing agent, dimethylamine and ethylenediamine as additives in alkaline zinc nickel alloy electroplating process.

In the case of citrate system, 791 brightener and polyether polyol were used as additives to obtain fine crystalline Zn Ni alloy coating.

In 1993, the relationship between the composition, chemical composition, phase composition and crystal structure of xzn-2 composite additive and abnormal Zn Ni Co deposition was proposed.

(9) In 1994, Xiong Gang, Zou Qun, etc. used nz-918 series additives to reach dk0.5? 6A / DM2 in alkaline zinc nickel alloy plating solution, and obtained the appearance alloy of bright nickel 8%? 10% zinc. The passivation film of (8%? 10% Ni) alloy coating is stable, and its corrosion resistance is more than 2 times higher than that of passivation.

D. Some views on the current situation of Zn Ni alloy electroplating in China

The research of zinc nickel alloy in China began in the 1980s, which was studied by acyl chloride electroplating process. In the subsequent research, experts successfully solved the key technology of acyl chloride electroplating of zinc nickel alloy, and found and determined the best combination of additives, which effectively inhibited the nickel deposition in the area of low cathode current density. As a result of this breakthrough, the process can be used for more complex electroplating shapes of steel sheets, and can also be used for barrel plating. Since 1993, a number of units have been put into industrial mass production. One of the main processing products is cable bridge, which has reached 1.2 million tons in recent ten years. It is understood that in the 1990s, acid zinc nickel alloy electroplating began to be used in industrial production. No matter whether the application of product variety and quantity is in the initial stage, alkaline zinc nickel alloy electroplating did not see industrial production in the 1990s.

Zinc nickel alloy electroplating has developed rapidly in China in recent years, but only alkaline zinc nickel alloy electroplating has been developed, and acid zinc nickel alloy electroplating has not been developed. As mentioned above, the process characteristics of acid zinc nickel alloy electroplating and alkaline zinc nickel alloy electroplating are similar to those of acid zinc plating and alkaline zinc plating. The process selection depends on the shape of the workpiece (except some steel). Some are suitable for alkaline technology, and some are suitable for acid technology. Therefore, according to the application of zinc nickel alloy electroplating process, the proportion of acid pickling and galvanizing should be close to that of zinc plating No.

It is understood that acid zinc plating accounts for more than 50% of the total amount of zinc plating in China, and alkaline zinc plating accounts for about 40% of the total zinc plating. Although there is no national statistics on acid zinc nickel alloy coating, we estimate that it does not exceed 10%. The reason for the low proportion of acid zinc nickel alloy electroplating is that a large number of acid zinc nickel alloy electroplating should be commonly used in the alkaline zinc nickel alloy electroplating process. Only according to the coal mine hydraulic column, the national electricity consumption is more than 1 million. Numerous electroplating units commonly use alkaline zinc nickel alloy electroplating process instead of acid zinc nickel alloy electroplating process. According to experts, in the two research and development processes and production practice, under the same coating content, nickel processing has the same coating thickness and similar corrosion resistance. The zinc nickel alloy electroplating process cost can be reduced by 50% and the production can be increased by more than twice. In this paper, we do not intend to cause a discussion on the common reasons for the development of zinc nickel alloy electroplating in China in recent years, but only predict that this situation will change in a few years, and the acid zinc nickel alloy electroplating process will gradually increase to its proportion.