Thesis
Recubrimientos de Pd (Ag)-ZrO2 obtenidos por CVD para electrodos utilizados en la purificación electroquímica de aguas de desecho
Autor
IQ Ferrétiz Anguiano, Jorge Luis
Institución
Resumen
In this research Pd – ZrO2 composite thin films were synthetized by Metalorganic
Chemical Vapor Deposition (MOCVD) in order to obtain anticorrosive coatings for electrodes
used in the technique of water treatment called Electrodyalisis. Coatings were deposited on
AISI 304L stainless steel substrates in ratios of 10 – 90, 20 – 80 and 30 – 70 wt % Pd and Zr
precursors (acetylacetonates) respectively, and temperatures of 450, 500 and 550 °C. Gas
flows were adjusted at 130 cm3min-1 at ratio of 20 – 80 % vol of O2 – Ar, and pressure was
maintained at less than 1 Torr.
Structural characterization was carried out through X-Ray Diffraction (XRD) showing the
presence of metallic palladium and zirconia in cubic and tetragonal phases; palladium
diffusion inside zirconia matrix was influenced by deposition temperatures and compositions.
Topographic characterization was performed by Atomic Force Microscopy (AFM), films
showed a uniform and columnar growth; dome size and roughness were acquired with this
technique too.
Temperature effect on morphology and electrochemical behavior was clearly
demonstrated by Scanning Electron Microscopy (SEM) and Electrochemical techniques
respectively: highly compact and crackless morphology was showed at lower temperatures and
medium compositions, the highest charge-transfer resistance was also obtained at this
temperature; whereas mores stresses appeared in the film and the charge-transfer resistance
decreased significantly at higher temperatures.