Effect of porous alumina coatings on decreasing hydrogen damage to Pb(Zr,Ti)O3

Alumina coatings were applied to Pb(Zr,Ti)O3 plates using the sol-gel technique, to explore the possibilities of decreasing the H2 damage to PZT. The coating process development cycle included dip coating in 10 wt.% boehmite sol and firing at 450 °C in air for 5 h. The functionality of the coatings against hydrogen damage was evaluated using water electrolysis in 0.1 M NaOH solution, with a constant current density of 100 mA/cm2 and 7-10 V. Significant reduction of the hydrogen damage was observed even though the coatings were highly porous. The mechanism by which the porous alumina coating decreases the hydrogen damage is tentatively proposed as prevention of the access of atomic hydrogen to the surface of PZT. Through this mechanism the porous coatings promote recombination of hydrogen atoms into hydrogen molecules on the electrode surface and within the pores of the coating, which prevents the access of the damaging atomic hydrogen to the surface of PZT.