LOW-TEMPERATURE ELECTROCHEMICAL SYNTHESIS OF ZRO2 FILMS ON ZIRCONIUM SUBSTRATES - DEPOSITION OF THICK AMORPHOUS FILMS AND IN-SITU CRYSTALLIZATION ON ZIRCONIUM ANODE

The feasibility of synthesizing crystalline ZrO2 films at low temperat ures was evaluated using an electrochemical method. Anodization of zir conium-metal substrates in tetraethyl ammonium hydroxide (TEAOH) solut ions under constant applied voltage conditions at similar to 25 degree s and similar to 100 degrees C was investigated. The chemistry and mic rostructure of the anodic oxide films deposited on the zirconium-metal substrates under the above conditions were characterized using X-ray diffractometry and scanning electron microscopy. The results indicated that, with sufficiently high applied voltages (in the range of 300 V) at pH similar to 9.5, the initial dissolution of the zirconium anode resulted in the local saturation of the electrolyte solution with Zr4, forming Zr(OH)(5)(-), which deposited electrophoretically on the ano de as a thick, gelatinous film at 25 degrees C. Similar treatments at 100 degrees C resulted in an in situ crystallization of Zr(OH)(4) gel to monoclinic ZrO2.