ELECTROLYTIC PLATING OF BLACK CHROMIUM ON METALS,
Abstract
Methods of electrolytic plating of metals with black chromium from electrolytes containing chromic acid and activator substances are known. When such substances are not present, hydrogen is given off from the cathode and the deposition of chromium does not take place. The proposed method is distinguished by the use of an electrolyte containing (in grams/liter): chromic acid CrO3, 150-400; the fluorine compound cryolite Na3AlF6, 0.1-0.4; a compound of iron oxylate 15-75; and chromium protector 1.5-3 at c.d.=5-15 A/sq dm with a short period (1-2 minutes) initial current pulse of c.d.=25-50 A/sq dm to obtain a uniform matte coating. Fluorides (cryolite) serve as the activating agents. Iron salts (oxylate) improve the coating power of the solution and decrease the luster of the coating. The coatings have a deep-black color and possess good protective qualities and adequate mechanical durability. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 21, 1968
- Accession Number
- AD0683968
Entities
People
- A. G. Samartsev
- N. V. Andreeva
Organizations
- National Air and Space Intelligence Center