Zinc plating - alkaline
A zinc plating belongs to the basic corrosion resistance coatings (CRC) whose most important function is to protect the base material against the atmospheric corrosion processes. Zinc coating significantly increase the usable lifetime of materials while reducing maintenance and replacement costs. A principle of its protection lies in difference of electrochemical potentials of protective layer (Zn) and base material (Fe). Less noble metal layer (Zn) which is in electric contact with the nobler substrate (Fe) appears as an anode in moist corrosive atmosphere. That is why Zn is being dissolved (white rust) whereas the base material is staying protected against the rust as a cathode (equivalent to the galvanic cell). The protection is effective as long as the rest of corrosion free zinc remains present on the top.
In our company we use alkaline, cyanides free zinc system which is nowadays replacing in history more utilized acid zinc solutions. Acid zinc technologies became less common overall and they are nowadays restricted to immaterial part of production industries (e.g. wirework).
Modern technique of alkaline zinc coating brings many functional and operating benefits in comparison to the older acid zinc technology. At first it saves needed time, consumed energy and required amount of Zn to get the sufficient protective layer. Due to the additional chemical surface depolarisation by the chemicals present in the solution alkaline zinc plating enable to decrease the differences in thickness in the high an low current density areas. That is why the deposit thickness distribution varies in narrow range. The zinc precipitation in high current density is inhibited so that the risk of heterogeneous grainy formation is minimalized.
This results to optimal metal layout, uniform appearance and high brightness in the whole current spectrum. Lower content of organic additives as in the working solution as for the replenishment allows to double the coated surface (compared to conventional acid solutions). It also improves the adhesion of following passivation layers to Zn layers due to the lower organics incorporation into the coating.
It is possible to obtain many various colour finishing with usage of the wide scale of many CrIII+ passivations or CRVI+ conversion coatings according to the customers' demands. We are able to provide or eventually to arrange this final appearance: blue, thick layer - transparent/iridescent CrIII+ paasivation, yellow, olive drab green and black CrVI+ chromate. In case of excellent corrosion resistance request we are able to use additional sealing to reach the maximal resistance.
Layer properties
- Most common, price-worth corrosion protection for steel and iron alloys.
- Relative soft and ductile coating characteristic by its bright-light appearance.
- Possibility to improve the corrosion resistance by various types of following CrIII+ passivation, CrVI+ chromating and final sealing.
- Possibility to create many different final appearance in these hues: blue, yellow, olive drab green, black, transparent/iridescent.
Deposition - dimension
- 5 - 15 μm (according to the customer demands)
Way of processing
- Barrel plating
- Rack plating - in depend of deal
Basic material - substrate
- Steel and iron alloys
Application field:
- Industry constructions for internal and external usage.
- Coupling material - screws, nails, nuts.
- Sheet metal, wire netting, piping.
- Machine - corrosion resistance coatings of outer parts of facilities.
- Automotive industry - body protection, break elements, etc.