| 摘要 |
824,334. Electrodeposition of chromium. METAL & THERMIT CORPORATION. July 24,1956 [July 26, 1955], No. 22888/56. Class 41. A method of producing a chromium-plated article of hard steel comprises passing a current of 1 to 6 amperes per square inch to said article as cathode in an aqueous chromium-plating bath having a chromic acid content calculated as CrO 3 of from 400 to 800 grams per litre and containing dissolved sulphate as catalyst at a temperature of 120‹ to 170‹ F., the ratio of CrO 3 to said dissolved sulphate being of from 75: 1 to 150: 1, so plating chromium on the article to form a coating at least 2 mils. thick, heating the plated article to a temperature of from 200‹ to 800‹ F. for a time sufficient to produce a chromium-plated article of steel having a fatigue strength of at least 70% of that of the unplated original steel. The plating bath may contain and be partially neutralized by sodium, potassium, calcium or ammonium radical. These may be added in the form of calcium oxide or hydroxide, sodium carbonate or hydroxide, potassium hydroxide or carbonate, and ammonium hydroxide or carbonate. The chromic acid may be supplied to the bath as such and the sulphate in the form of sulphuric acid or calcium sulphate. |
