GB1507126A - Method and apparatus for indicating embrittlement due to hydrogen permeation during surface treatment processes - Google Patents

Abstract

1507126 Metal embrittlement determination ISRAEL AIRCRAFT INDUSTRIES Ltd 13 April 1976 [24 April 1975] 15021/76 Heading G1N An indication of embrittlement of a metal part due to hydrogen permeation during etching or plating is provided by immersing a probe comprising a plurality of electrodes one being a membrane electrode and of the same metal as the part and an electrolyte into the bath during treatment applying a voltage between the electrodes sufficient to oxidize hydrogen diffusing out of the membrane electrode and measuring the probe current. Preferably a counter electrode and optionally a reference electrode are placed in the electrolyte. The inner face of the membrane electrode is maintained positive with respect to the counter electrode and the outer face of the membrane electrode is, in a plating bath, made negative relative to the plating anodes. As shown, the probe comprises insulating plastics (e.g. PTFE) chamber 2 containing 0À2 N NaOH. Membrane electrode 14 is fixed to chamber 2 by nut 16 and has a palladium inner layer connected to lead 19. A platinum foil counter electrode 20 and saturated calomel reference electrode 24 are connected to leads 20, 26 respectively. The sensor is connected to a potentiostat Which maintains the membrane electrode at a positive potential corresponding to a hydrogen partial pressure of 10<SP>-7</SP> - 10<SP>-14</SP> torr.