METHOD FOR REMOVAL OF FILLING MATERIAL FROM HOLLOW FORGING AND FORGINGS TREATED BY SAID METHOD

摘要

PURPOSE: To easily produce hollow gold products by winding gold foil around cores consisting of copper, copper alloy, etc., then immersing the cores into an acidic electrolyte having a specific compsn. and subjecting the cores as anodes to an electrolytic treatment and to melt and to remove. ;CONSTITUTION: The metallic work pieces formed by winding the gold foil around the surfaces of the cores made of the copper and copper alloy in the state of not welding part of its end are immersed as the anodes into the electrolyte of 35 to 85°C contg. 7 to 18g/l (more particularly 10g/l) H₂SO₄, 35 to 75g/l (more particularly 50g/l) CuSO₄, 5H₂O and 20g/l Zn and further, contg. materials, such as ammonium sulfate, sodium sulfate, dextrin, polyglycol and thiourea, which change the crystallization of cathodic deposits. The workpieces are subjected 4o the electrolytic treatment at a cathode current density of 2 to 3.5A/dm₃ by impressing voltage of 200 to 900mV between the workpieces and the cathode made of a pure copper plate. The copper-base metals as the cores melt and deposit as electric copper on the cathode. The hollow gold products having no copper-base metal cores are obtd. at the anodes.;COPYRIGHT: (C)1991,JPO