Krishnan, R.M. and Parthasarathy, N.V. and Natarajan, S.R.
(1986)
Electrodeposition of black chromium from self regulating electrolytes.
Bulletin of Electrochemistry , 2 (3).
pp. 243-246.
ISSN 0256-1654
Abstract
A strong need islelt by a practical plater for a black chrome bath which can be operated around the
ambient temperature (30°C) and at normally employed current densities and preferably not associated
with any necessity of controlling the catalyst concentration. In the work now reported, experiments were
carried out on the solubility of calcium fluoride gt 30°C in chromic acid solutions with a concentration
range of .200- 425 g 1 I. Barium hydroxide was introduced in adequate quantities to desulphate chromic
acid and also to counteract any drag-in of sulphate. Hullcell experiments were carried out at 23" and
31°C in order to assess approximately the cunent density range over which black chromium deposition
was possible. This was followed by experiments in plating to study the effects of different parameters like
chromic acid concentration, current density. temperature and duration of deposition on the nature of
finish and deposition.
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