GB812817A - Electrolytic production of titanium - Google Patents

Abstract

812,817. Electrolytic production of titanium. SOLAR AIRCRAFT CO. May 19, 1955 [May 21, 1954], No. 14450/55. Class 41. Dense solid titanium or an alloy thereof is cathodically deposited from an all-fluoride molten electrolyte consisting of either one or more alkali metal fluotitanates or a mixture of one or more fluotitanates and one or more fluorides of alkali metals, alkaline earth metals and magnesium and containing at least 50 per cent of fluotitanate salt, said electrolyte being maintained free of nitrogen, oxygen, and water, as by means of an inert atmosphere such as carefully purified and dried argon. Preferably if the fluotitanates used are other than those of the alkali metals, the fluoride content should be at least 10 per cent. The titanium content of the bath may be replenished by the addition of titanium tetrafluoride. The operating.temperature of the bath may be between 1080‹ and 1800‹ F. and the preferred cathode current density is between 0.1 and 5 amps./sq. in. although dendritic deposits may be obtained at up to 32 amps./sq. in. During deposition the bath may be agitated either by inducing highfrequency waves therein without connections to or within the cell or by directly moving the bath by stirring, movement of the electrodes, bubbling argon through the bath or by applying A.C. between pairs of cathodes to heat these more than the anodes which are arranged alternately with the cathodes. The applied A.C. also produces a reverse plating action. The cathodically deposited metal is surrounded by a lower titanium fluoride outer deposit which is water-soluble. The titanium may be separated from the cathode which may be of iron, copper, molybdenum, mild steel, stainless steel or a chromium-iron-nickel base alloy by an acid which attacks the cathode which may be in the form of moulds. Graphite or carbon anodes are employed and carbon tetrafluoride is evolved at the anode. As shown, the bath is contained in a graphite crucible 56 serving as anode within a metal shell 46 to which it is electrically connected and the lower half of which is disposed within a furnace 48. The upper half of the shell is surrounded by a cooling coil 54 and serves as a cooling chamber for the cathode 64 when this is extracted from the melt, a movable partition (not shown) being provided between the two halves of the shell. Argon may be introduced into the bath through the hollow cathode and into the cooling chamber through a separate supply pipe 78. The top 40 of the cooling chamber is removable for changing the cathode and is provided with a valve-controlled pipe 82 for making additions to the bath. The cathode may be provided with a heating element to raise it above the bath temperature and has an anode gas shield 72. Specification 678,807 is referred to. Reference has been directed by the Comptroller to Specification 713,446.