J. Krysa et al., EFFECT OF COATING THICKNESS AND SURFACE-TREATMENT OF TITANIUM ON THE PROPERTIES OF IRO2-TA2O5 ANODES, Journal of Applied Electrochemistry, 26(10), 1996, pp. 999-1005
The effect of coating thickness and the effect of surface treatment of
the titanium base metal on the surface morphology and electrochemical
properties of IrO2-TaO5 anodes were investigated. It was observed tha
t for an iridium content of 0.45-1.2 mg cm(-2) the service life is pro
portional to the iridium content in the coating. During etching of tit
anium in 5% HF at 25 degrees C a surface with macroroughness is formed
, while during etching in HCl at 30, 50 and 80 degrees C a microrough
surface with visible pitting is formed. The morphology of the IrO2-Ta2
O5 active layer (0.32-0.39 mgIrcm(-2)) depends strongly on the pretrea
tment of the titanium base metal. After etching of titanium in HF, the
resulting IrO2-Ta2O5 layer is adherent to the macrorough surface of t
he titanium base metal. After etching of titanium in HCl the resulting
surface of the IrO2-Ta2O5 layer is microrough with partly filled pitt
ing holes. The service life of IrO2-Ta2O5 coating with different rough
ness does not differ and has a value of 1500+/-400 h (0.5 M H2SO4, 25
degrees C and j=2 A cm(-2)).