Cobalt-chromium coatings by electrodeposition: Review and initial experimental studies

Abstract

The attraction of electrodepositing composite coatings is discussed in relation to sprayed coatings. The present state of the development of composite electrodeposited coatings is reviewed and the main limitations, such as the bulk hardness of the matrix, are discussed. The feasibility of developing a generation of wear resistant cobalt-chromium composite coatings and electroforms is examined in relation to the factors which would govern such a development. Cobalt-chromium co-deposition is reviewed and the results related to the requirements for composite co-deposition. Initial experimental results are reported on cobalt-chromium deposition from a fluoborate bath and the dimethylformamide-water bath. It is shown that the rate controlling factor is the inability to sustain co-deposition and thus achieve the requisite thickness for coatings and electroforms. It is suggested, on the basis of the results available, that predictable cobalt-chromium composites could be developed by the 1980's based on chromium solid solutions to achieve the hardness, and containing a high volume fraction of particles.