A process for the hard chrome plating of the inner pipes

摘要

667,227. Electroplating the interior of tubes. ELECTRO METALLHARDENING CO., SOC. ANON. Oct. 19, 1949 [March 18, 1949], No. 26878/49. Class 41. The interior of a tube c is electro-plated with chromium by a process in which the electrolyte enters a hollow anode e through an inlet a at one end, passes out through apertures b at the other end, flows in the reverse direction through the space between the anode and the interior of the tube c and is discharged through an outlet d. The anode consists of a hollow lead tube f surrounded by a copper tube g which is connected at each end to a source of current supply. The tube g has a lead cover h. The apertures bare provided with a protective covering of lead. The electrolyte is continuously recirculated, chromic acid being added continuously or at intervals. The plating of the tube may be freed from hydrogen by subjecting the tube to a high vacuum, followed, if necessary, by slow heating at a temperature below the annealing point of the metal.