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Corrosion potential study of the Western Australian 1911 coronation medal
Conference paper

Corrosion potential study of the Western Australian 1911 coronation medal

W.R. Bloom and I.D. MacLeod
Corrosion and Prevention 2018 (Adelaide Convention Centre, Adelaide, 11/11/2018–14/11/2018)
2018
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Abstract

A series of eleven commemorative 1911 coronation medals struck in Western Australia and manufactured by Stokes & Company were studied using corrosion potential measurements in 0.1 M sodium chloride to test for debasement of the medals. The falling values of Ecorr indicated that there were a significant number of defects in the surface of the silver medallions and that the different end voltages indicated that the core composition of the medals was not the same. The lowest Ecorr values were associated with a faster rate of falling Ecorr data and these medallions also had lower initial voltages. X-ray fluorescence analysis of both the front and back of the medallions provided chemical composition of the Medals which had been silvered with a silver amalgam before heating. This process left a microporous silver layer which was 8-10 µm which was readily abraded on the high points of the heavily embossed dies.

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