Sandblasting effect on performance and durability of Ti based IrO2 –Ta2O5 anode in acidic solutions

Abstract

The effect of applying sandblasting during pretreatment while preparing titanium based IrO2 – Ta2O5 anodes by the conventional method was investigated. It was observed that sandblasting influences the surface morphology both before and after coating as deeper and smaller etching pits are obtained on the substrate before coating process and rougher surface is obtained after coating. As a result larger outer electrochemical active surface area (ECSA) is obtained on the anodes with sandblasting, which was determined based on cyclic voltammetry, whereas the inner ECSA is independent of the pretreatment. The polarization measurements in a quasi-steady state reveal that sandblasting has slight influence on the catalytic activity. Accelerated lifetime tests were carried out in acidic 0.9 mol L−1 Na2SO4 solution (pH = 2) at a current density of 5 kA m−2 under galvanostatic conditions. It shows that sandblasting would shorten the lifetime of the anode due to oxidation of the titanium substrate. This might because of the shorter distance between the lowest spot of the outer coating surface and the highest spot of the outer substrate of the anode after applying sandblasting in titanium substrate pretreatment.