Service Communautaire d'Information sur la Recherche et le Développement - CORDIS

Composition modulated alloy coatings for enhanced technological properties

Properties of composition modulated alloy (CMA) coatings produced by electrochemical methods were evaluated. CMA coatings are coatings in which distinct compositional changes have been induced in order to enhance specific technological properties. Such coatings have proven to exhibit properties superior to those of the corresponding metals and alloys of the same material, but the technique was not developed to industrial usage and required basic research to be completed to understand process parameter behaviour adequately.

The necessary facilities for electroplating under controlled current/potential and hydrodynamic conditions were constructed. This involved the set-up of rotating cylinder rigs and construction of a new computer aided pulse plating equipment enabling overpotential control using a three electrode system. Techniques for plating CMA coatings were established including both single bath and dual bath electrodeposition. The copper-nickel CMA system was used as a model system for testing the involved deposition techniques and for fundamental studies. A large number of alloy plating solutions selected from nickel-phosphorus type alloys, cobalt-molybdenum type alloys and zinc alloys were characterized from an electrochemical point of view with the purpose of identifying electrolytes very suitable for deposition of CMA coatings. CMA coating were deposited form selected suitable electrolytes and evaluated from an industrial point of view. The evaluation mainly concentrated on corrosion and wear testing. The results confirmed that electroplating is a suitable technique for manufacturing CMA materials. The two main principles for electrodeposition of CMA coatings - the dual bath and the single bath techniques - exist in a number of variations which can be used with advantage depending on the specific CMA coating in question.

Reported by

Linköping University
58183 Linköping