An electrodeposition process and a bath therefore are disclosed for performing the electrodeposition of hard smooth coatings of trivalent chromium. The electrodeposition process is accomplished energy efficiently. The bath includes chromium chloride as a source of chromium, citric acid to complex the chromium, and a wetting agent which is preferably Triton x-100. Preferably, bromide is also provided in the solution to maintain the hexavalent chromium production at the anode at a low level. Ammonium chloride is also preferably provided to improve the conductivity and also the current distribution in the bath. Boric acid is provided to advance the reaction kinetics. The pH of the bath is maintained at approximately 4.0 and the temperature is maintained at approximately 35° C. Either a direct current or pulsed current is used for the deposition process. Hard smooth coatings of trivalent chromium are deposited through use of the process and the bath of the claimed invention.

Electrodeposition of chromium from a trivalent electrolyte

An aqueous acidic composition suitable for etching which contains an acid and a thiourea compound, and use thereof.

Process for etching chrome

The present invention relates to a trivalent chrome alloy plating solution, a Cr-Ti-Au alloy plating solution, a Cr-Ti-Ni alloy plating solution, a Cr-Ti-Co alloy plating solution, and a plated product. The trivalent chrome alloy plating solution uses a trivalent chrome compound, a conductivity assistance agent for increasing the electric conductivity of trivalent chrome ions, a depolarizer including at least one among NH_4Br, NaF and NaBr, and one among Co, Ni and Au dissolved in a citric acid or DL-Tartaric acid aqueous solution as a metal reducing agent for reducing an alloy plated layer from the trivalent chrome ions. Therefore, the present invention can provide industry-based technology for completely replacing hexavalent chrome plating which is expected to be subject to an environment restriction as a cancer-causing agent as well as freely forming decorative and industrial hardened chrome plated layers by creating various chrome alloy plated layers using trivalent chrome ions.

3 -- -- -- electroplating chromium alloys

A method for brightening an electroplated chromium deposit wherein the deposited chromium is contacted with a solution having a constituent capable of forming complexes with chromium hydroxide species and of detaching the complexes so formed from the surface of an electroplated deposit. Preferably the solution is an alkaline ferricyanide solution or a solution of sodium dichromate in sulphuric acid.

Method of brightening electrodeposited chromium

Solution pour rendre plus brillant le chrome depose par galvanoplastie. Elle comprend un composant capable de former des complexes avec l'hydroxyde de chrome et de retirer ces complexes de la surface du chrome depose Les solutions preferees sont une solution alcaline de ferricyanure, et une solution de dichromate de sodium dans de l'acide sulfurique. Application a l'industrie du chrome.

James M. Vigar

Papers

Method of brightening electrodeposited chromium

Solution et procede pour rendre plus brillant le chrome depose par galvanoplastie, et chrome ainsi obtenu