GB936409A - Improvements in or relating to current density measurement in electrolysis - Google Patents

Abstract

936,409. Current measurement; measuring electrodes. MARCONI'S WIRELESS TELEGRAPH CO. Ltd. July 4, 1961 [Sept. 7, 1960], No. 30874/60. Class 37. The current density of an electrolyte bath over a small area of an electrode therein is measured as a function of the potentials between such electrode and each of two points in the electrolyte which are closelyspaced at predetermined distances from the electrode; such potentials being additively combined so as to eliminate the effect of the electrical resistance of the electrolyte from the resultant. An electroplating bath 1 (Fig. 1), containing anode 2 and work cathode 3 in electrolyte 4 has an immersed insulating carrier 6 with subsidiary metal electrodes 7, 8 of similar material to the cathode; against which the carrier is placed so that electrode 7 is spaced therefrom by a distance twice the spacing of electrode 8. The latter is connected to terminal 9 of an oscillating relay and to earth over resistance 2r, and the former is connected to other relay terminal 9 over resistance r; the terminal being returned to earth over other terminal r. Oscillatory potentials from the relay armature 11 are amplified to operate a meter 12 representing the difference of the potentials, which is shown to be proportional to the current density. The electrode carrier 6 comprises a hollow handled plastic tube with flat face 14 applied to the electrode, containing internally the spaced and perforated parallel electrode discs 7, 8 (Fig. 2). An agitator may be assembled on the electrode carrier, and a single electrode may alternatively be placed successively at two points of the electrolyte for measurement and comparison of the developed potentials. The subsidiary electrodes may be disposed at similar distances from the cathode and be made of different sizes: Similar measurement may be effected at bath anode.