The electrodeposition of Tin/Zinc, Tin/Chromium and Tin/Zinc/Chromium alloys
The electrodeposition of tin/chromium and tin/zinc/chromium is a new field of research. This field
was investigated because it may be of commercial, as well as scientific, interest if a range of alloy
compositions could be sustainably deposited from environmentally acceptable electrolytes.
With no published work to guide this research difficulties were encountered in producing
sustainable deposition procedures. A novel electrolyte that deposited tin/chromium alloys in a
range of compositions was produced. This electrolyte was adjusted to produce novel
tin/zinc/chromium deposits in a range of compositions. However the thickness of deposited
tin/zinc/chromium was limited to 300nm.
It was hypothesised that polymerised chromium glycine could be used as a weak brightener to
increase deposit thickness. This produced another novel electrolyte and it was confirmed that
chromium could be codeposited from polymerised chromium glycine with tin and zinc. This
electrolyte produced deposits in a range of compositions and produced tin/zinc/chromium deposits
up to 3Jlm thick. The ability to deposit chromium from the polymerised electrolyte was enhanced
by the codeposition oftin. This induced codeposition of chromium with tin had not previously
It was observed that tin metal was dissolved by the chromium glycine electrolyte and that this
dissolved tin was not precipitated out. It was suggested that the dissolved tin could be
electrodeposited with chromium. Experimentation confirmed this hypothesis. The alloy produced
was rich in chromium, 6Jlm thick and of a bright appearance.
Tin/chromium and tin/zinc/chromium deposits were analysed by Mossbauer and X-ray
Diffractometry and p-tin identified in all samples examined. Significantly tin only phases could
not explain the Mossbauer and X-ray diffraction results, the presence of other tin
microenvironments are required. However the lack of standards for comparison made
identification of such microenvironments difficult.