Electroplating of Cyclic Multilayered Alloy (CMA) Coatings

Abstract

A new technique has been developed for producing laminated composites of cyclic multilayered alloy (CMA) electrodeposits. The thickness and composition of the individual layers of the CMA deposits are altered precisely and conveniently by cyclic modulation of the cathodic current or potential during electrodeposition. It is thus possible to modify the structure to obtain laminated composite coatings which may have desirable engineering properties. Wear and corrosion resistances, mechanical hardness and strength, as well as certain magnetic, optic, and electronic properties of the plated composite alloys should be, in principle, straightforward to design and fabricate. The CMA technique was demonstrated by plating a wide variety ofAg-Pd CMA structures. Fine structures, with repeat distances as small as 0.05 ~m, were obtained. Both square and triangular waveforms were applied to produce sharp or gradual composition variations, respectively. The resulting deposits * Electrochemical Society Active Member. 1 Present address: MPI, Santa Clara, California 950,51. -~Present address: Oxy Metal Industries, Warren, Michigan 48089.

Electrodeposition and Characterization of Alloys and Composite Materials

“…Deposition of such structures was first demonstrated by Brenner [4], while Cohen et al [97] obtained an Ag-Pd alloy with periodically changing composition by alternating the current density, and such structure showed improved wear performance of electrical contacts. In order to obtain laminar metal structure with the thickness of individual layers (with the second layer being Cu-Ni alloy with small amount of Ni) of 300 nm in the system Cu-Ni, pulsating regimes were used [98,99].…”

“…It was shown that such structures possessed higher tensile strength [98] and microhardness [99]. In the application of pulsating regimes [97][98][99] three types of pulses, schematically presented in Fig. 1.36, were used.…”

Microstructural and Mechanical Characterization of Multilayered Iron Electrodeposits

“…For example, it has been observed that silver/palladium multilayers can still maintain layer planarity in spite of small disruptions (compared to diffusion layer thickness) in the electrodeposit, resulting from the incorporation of inclusions (Cohen 1983). However, larger disruptions may be amplified as growth is favoured in the surrounding areas of an inclusion site (Cohen 1983). Consequently, surface roughness increases as deposition continues and planarity may be lost.…”

Electrodeposited Nanostructured Films and Coatings: Synthesis, Structure, Properties and Applications

“…Even multilayered or compositionally modulated alloys (e.g. Cu-Pb [16], Cu-Ni [17,18], Ag-Pd [19], Ni-P [20]), metal matrix composites (e.g. Ni-SiC [3]), ceramics (e.g.…”