METHOD FOR MEASURING CONCENTRATION OF HYDROFLUORIC ACID IN PICKLING BATH CONTAINING HYDROFLUORIC ACID

摘要

PURPOSE:To improve pickling efficiency by measuring the galvanic current between two different metallic electrodes immersed in a pickling bath and measuring the correlating concn. of the hydrofluoric acid in the pickling bath in accordance with the measured current. CONSTITUTION:A titanium electrode 4 and a stainless steel electrode 3 are immersed in the pickling bath 2 consisting of nitric acid and hydrofluoric acid contained in a vessel 1 and an unresisted ammeter A is connected between said two electrodes. The electrode 4 acts as an anode and the electrode 3 as a cathode. An extremely good correlation is admitted between the galvanic current flowing from the electrode 3 to the electrode 4 in the direction reverse from the electron flowing in a conductor in this stage and the concn. of the hydrofluoric acid in the bath 2. The concn. of the hydrofluoric acid can be easily and exactly measured from the measured current value and therefore the pickling bath is maintained always in the good condition. The good pickled surface is obtd. and the pickling efficiency is improved by the above-mentioned method.