EXPERIMENTAL INVESTIGATION OF THE DOUBLE-LAYER CAPACITY, X-RAY-DIFFRACTION AND THE RELATIVE SURFACE CONTENT OF TIH2 DURING PRETREATMENT OF TITANIUM USED FOR THE PREPARATION OF DIMENSIONALLY STABLE ANODES WITH RUO2 AND OR IRO2 COATING/

The first operation for the production of dimensionally stable electro des based on titanium sheets covered with a layer of RuO2 and/or IrO2 is the treatment of titanium in HCl solution. The surface layer struct ure of titanium treated in HCl has been determined by X-ray diffractio n, electron microscopy and by measurement the double layer capacity. O bservation of the surface of etched electrodes by EM has shown the TiH 2 (from the X-ray diffraction) formed during dissolution of titanium i n an active region is not regularly distributed over all the surface a rea compared to the regularly distributed TiH2 formed during the catho dic polarization of titanium. The relative content of TiH2 was indepen dently determined by X-ray diffraction and by vacuum desorption of H-2 from the decomposition of TiH2 and these values are directly proporti onal. The increase of the relative surface content of TiH2 (determined by X-ray diffraction) leads to the decrease of double layer capacity.