Technical requirements for surface galvanized kneading

Characteristics of zinc-nickel alloy coating

Among zinc-based alloys, zinc-nickel alloy coating is a new type of excellent protective coating,   which is   suitable for use in harsh industrial atmosphere and harsh Marine environment. The corrosion resistance of zn-Ni alloy with 7~9% nickel content is more than 3 times that of zinc coating. The corrosion resistance of the zinc-nickel alloy coating with about 13% nickel content is more than 5 times   that of the zinc coating,and it has   the best corrosion resistance.

Due to its excellent properties such as high corrosion resistance, low hydrogen brittleness, weldability and machinability, zinc-nickel alloy has long attracted people's attention, and its application scope is more and more   extensive. Zinc-nickel alloy coating has high melting point and is suitable for automobile engine parts plating.   Low hydrogen embrittlement, suitable for electroplating on high-strength steel; Can be used as a substitute   cadmium coating,   mostly used in military products.

Zinc-nickel alloy plating solution is mainly divided into two types: one is a weakly acidic system,   which has   simple composition, high cathode current efficiency (generally above 95%), stable plating solution and easy operation. The other is the alkaline zincate plating solution, its main advantages are: the plating solution dispersion ability is good, the coating alloy composition is more uniform in the wide current density range, the coating thickness is also uniform, the corrosion of equipment and workpiece is small, the process is easy to operate, the process is stable, and the cost is low.

Compared with galvanized layer

1.Corrosion resistance

Zinc plating and zinc-nickel alloy as functional coatings, zinc-nickel alloy in corrosion resistance is much   better than galvanized, which is the main reason why researchers spend a lot of time and energy to develop zinc-nickel alloy. After color passivation treatment, the zinc-nickel alloy coating can easily pass 1000 hours   without white rust under neutral salt spray, and the galvanized layer can pass 120 hours after color passivation. After white passivation treatment, zinc-nickel alloy coating can pass 400 hours without   white rust under   neutral salt spray, while galvanized layer can pass 96 hours after blue and white passivation.

2.appearance

In general, the color passivation layer of zinc-nickel alloy is not as bright as that of galvanized layer,   especially   when the nickel content of alloy coating is high; The white passivation color of zinc-nickel alloy is not as blunt   and white as that of galvanized layer. When it needs to be explained, people's understanding of things is often preconceived, and the color of the product is also the same. With the increase of zinc-nickel alloy products   on   the market, people have been able to accept the difference in color between the zinc-nickel alloy passivation   layer and the galvanized passivation layer. 

3.Production cost

Because the zinc nickel alloy coating contains about 13% of metal nickel, the price of nickel is much higher thanthat of zinc (nickel: 191000 yuan/ton, zinc 18000 yuan/ton), so the electrogalvanized nickel alloy is much higherthan the electrogalvanized production cost. 

4.Process maintenance

Basic zincate galvanizing has now been widely accepted by the market, and the zinc-nickel alloy process as a   "new" electroplating process has not been widely used, and the knowledge is limited. In fact, zinc-nickel alloy   has been used in the market for more than 20 years, and it has developed rapidly. Now the process has been quite mature, stability even more than galvanized.