GB568454A - Improvements in and relating to electrolytic polishing - Google Patents

Abstract

568,454. Electrolytic polishing of metals. LANGLEY ALLOYS, Ltd., and MALIES, H. M. Oct. 4, 1943. No. 16228. [Class 41] An electrolytic cell for polishing metal surfaces comprises a rectangular box of moulded plastic or insulating material or of wood lined with paraffin wax, having along one wall 2 a series of apertures 3 '... 5 furnished with rubber rings 16 against which the specimens 6 . . . 8 to be treated are clamped by screws passing through a yokeshaped busbar 9. The cell is compartmented by partitions 20, 21, and a cathode formed, for example, of sheet copper, is shaped. to provide three portions 26 ... 28 opposite the respective apertures and figures 29, 30 co-operating with fixed abutments 31, 32 for detachably clamping the structure in place. For loading the cell, it is tiltally mounted by means of trunnions 33, 34 in arms 35, 36 and held by a latch 38, Fig. 4, in a position in which the specimens are clear of electrolyte, which is inserted through an aperture provided in wall 39. The cell is then moved into a position in which the wall 2 lies at the bottom. In use, a flat surface is formed on the specimen by turning or grinding with coarse emery, the specimen is put into place and voltage applied, the bath is moved to polishing position, and treatment continued for 35 to 40 minutes at an applied voltage of 1.5 corresponding to a current-density starting at 0.31 and falling to 0.24 amps./cm<2>. For an etched surface, the applied voltage is lowered to 0.8 for the last 2 to 3 minutes. The bath is then restored to the loading position, the specimens are rinsed and pickled in a 50% HCl solution, again washed with water and then with acetone to ensure satisfactory drying. A suitable electrolyte comprises two parts of commercial phosphoric acid (d.g. 1.875) diluted with three parts by volume of water. The treatment is applicable to copper or copper base alloys containing chromium, silicon, nickel, zinc, and/or manganese. A special fitment is provided for attaching small specimens to the apertures, Fig. 6 (not shown).