First, the two processes compare the advantages and disadvantages

Process characteristics acidic and alkaline zinc-nickel alloy plating zinc-nickel alloy plated with acidic and alkaline zinc galvanizing similar characteristics. The following are the main advantages and disadvantages of contrast of these two processes.

Cons Pros alkaline zinc-nickel alloy plating acid zinc-nickel alloy plating

1, throwing power (dispersion capability) Well, coating 1, throwing power (dispersion capability) is relatively low

Relatively uniform thickness distribution. Coating thickness uniformity is relatively poor.

2, the workpiece is high, low current density area coating 2, the workpiece is high, low current density area coating

The nickel content difference is small. The nickel content varied.

Advantages Disadvantages Alkaline zinc-nickel alloy plating acid zinc-nickel alloy plating

1, the current efficiency is low, generally about 50%, a high current efficiency, typically about 90 percent,

Slow deposition rate, 0.25 m / min or so. The deposition speed, up to 1.0 m / min or more.

2, the production of high operating costs. 2, low running costs, low compared with about 50% alkaline process.

3, to maintain the normal operation of the plating tank is relatively difficult. 3, to maintain the normal operation of the plating tank is relatively easy.

4, not plated cast iron, hardened steel, high carbon steel. 4, can be plated cast iron, hardened steel, high carbon steel.

Second, the two processes of selection

From the comparison of these two characteristics, advantages and disadvantages of the process, we can conclude that these two processes of selection depends on the geometry of the workpiece to be plated material and workpiece. In addition to the cast iron, carburized steel such materials, by other metallic material (mainly carbon) workpiece made of selection of the process will depend on the geometry of the workpiece, the principles of which are selected: a high current during the electroplating of the workpiece current density and density difference between the two workpiece low current density area larger alkaline process is used, and vice versa, is used an acidic process. For example, the central portion of the workpiece or a workpiece with a blind hole with its edge portion remote from the workpiece (e.g. impeller), this type of plating current density at the workpiece and the workpiece is a workpiece which high current density region of low current density region current density difference between the two is very large. In this case, the use of an acidic process, the coating thickness, and the difference of the plating nickel content of the low current density region and the high current density region of the workpiece is much greater than with an alkaline process. When plating is a simple shape of the workpiece, such as various types of roller cylinder, piston, fasteners, etc., due to the relative consistency of the surface current density, in this case, it should select an acidic process, because alkaline process The two big advantages of no longer make much sense, but the disadvantage of its own is quite prominent.

Third, the current situation of China's zinc plating nickel alloy that view

The research on the zinc-nickel alloy began in the eighties, we studied are all acid chloride plating process. The author in this study successfully resolved the key technical acid chloride galvanized nickel alloy - Locate and identify effective suppression of low cathode current density areas the best combination of additive nickel deposit. Because of this breakthrough, the process can be used for more complex shapes hanging plating steel parts can also be used for barrel plating. Since 1993 has a number of units with this process into industrial mass production, one of the main processing products are cable bridge, in the last decade of its processing capacity of 1-2 million tons. But I know, acidic zinc-nickel alloy plating, although beginning in the late nineties for industrial production, but the product variety and quantity terms both of its application are in the initial stage, as the alkaline zinc-nickel alloy plating nine 1980s not been reported for industrial production.

The rapid development of zinc-nickel alloy plating or popular thing in our country in recent years, but the development of only basic zinc-nickel alloy plating, acid zinc-nickel alloy plating has not been a corresponding development. As previously mentioned, the process characteristics acid zinc-nickel alloy plating with alkaline zinc-nickel alloy plating is similar acid zinc and alkaline zinc characteristics, process selection are dependent on the shape of the workpiece (except in certain steel outside) Some suitable alkaline process, some suitable acidic process, therefore, supposedly used in a proportion of zinc-nickel alloy plating two processes should be acidic and alkaline zinc galvanizing ratio substantially close without proper disparity difference.

It is understood that China accounted for more than 50% acid zinc galvanized the total, accounting for about 40% alkaline zinc, zinc-nickel alloy plating and acidity, although not see national statistics but according to the author is not expected to exceed 10%. Nickel alloy plating reason such a low proportion of acid zinc is that a lot of this should be acidic zinc-nickel alloy plating workpiece now widely used in the alkaline zinc-nickel alloy plating process. It only coal mine hydraulic prop example, the national amount of over one million, countless loyal plating processing unit commonly used to this end alkaline zinc-nickel alloy plating process rather than acidic zinc-nickel alloy plating process. According to the author of these two processes development and production practice, this kind of work piece at the same plating nickel content, the same coating thickness, corrosion resistance similar situation, acidic zinc-nickel alloy plating process its production cost can be reduced by about 50% , output can be increased more than 2 times. The author did not intend to cause this recent zinc-nickel alloy plating two process anomaly to explore the development of China, but this situation will only predict in a few years will be changed, acidic zinc-nickel alloy plating process will gradually rise to the proportional share of it.