Chromium plating bath for producing non-iridescent, adherent, bright chromium deposits at high efficiencies and substantially free of cathodic low current density etching
AssigneeM&T Chemicals Inc.
InventorsHyman Chessin, Kenneth R. Newby
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Abstract
A chromium plating bath and process for producing a non-iridescent, adherent, bright chromium deposit at high efficiencies and high temperatures under conditions such that the process is substantially free of cathodic low current density etching. The bath consists essentially of chromic acid and sulfate in predetermined concentrations, and an organic sulfonic acid or salts thereof, where the ratio of S to C is .gtoreq.1/3, e.g. methyl, ethyl and propyl sulfonic acid, and methane and 1,2-ethane disulfonic acid. The bath is substantially free of carboxylic acids, phosphonic acids, perfluoroloweralkyl sulfonic acids, and halides.
Claims9
A functional chromium plating process for producing a non-iridescent, adherent, bright chromium deposit on a basis metal at a cathode efficiency of at least 22% at a current density of 77.5 a.s.d. and a plating temperature of 55.degree. C., which deposit is substantially free of grey or rough deposits or low current density etching, comprising
- electroplating chromium on said metal at a temperature of 45.degree.-70.degree. C. from a chromium plating bath consisting essentially of chromic acid and sulfate, and a non-substituted alkyl sulfonic acid, or salt thereof, wherein the ratio of S/C is .gtoreq.1/3.
Dependencies are inferred from the claim text.