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Improved zinc composite coating

Improvement of zinc (alloy) composite coatings through
electroplating as a coating technique; improvement of
corrosion resistance and tribological properties using
non-toxic components.

In the last decade a number of new processes have been developed introducing alloying metals such as nickel, cobalt and iron in order to retard the action of zinc on the steel substrate and as a result to decrease the formation of corrosion products upon zinc-coated parts. In a number of applications it is very important to reduce the volume of corrosion products on the surface, e.g. when tribological aspects of the coating are essential for the performance of the coated product (e.g. fasteners). A frequently applied process is to protect the zinc (alloy) coating with a chromate conversion coating in order to retard the production of interfering corrosion products. The processes used to apply such a protecting chromate conversion coating, however, are always based on the use of hexavalent chromium, which is considered as highly toxic nowadays and dangerous for operators as far as health and safety working with these coating processes in concerned. It is therefore important to develop alternative processes using less toxic compounds giving the same effect of retardation of corrosion products, and combine this aspect with intrinsic lubrication properties through co-deposition of a second phase with these characteristic properties. The aim of the project is: * the development of a composite coating based on a metallic phase of zinc (alloy) and an organic phase with combined corrosion-resistant properties and intrinsic self-lubrication properties * the composite coating will be developed for the application through electroplating using the zinc (alloy) plating bath as the base * for the application of the new coating technique the corrosion resistance of the applied hexavalent chromium- free composite coating should be equal or better than the conventional chromate-based conversion coatings * a demonstration on pilot plant scale and industrial scale of the composite coating process in order to prove this as a commercially and economically viable process without health and safety hazards for operators and users of the process.
Acronym: 
IMZICO
Project ID: 
1 931
Start date: 
01-04-1998
Project Duration: 
42months
Project costs: 
260 000.00€
Technological Area: 
Market Area: 

Raising the productivity and competitiveness of European businesses through technology. Boosting national economies on the international market, and strengthening the basis for sustainable prosperity and employment.