Influence of the experimental parameters on the synthesis process of yttria-doped zirconia sol–gel films

The influence of the alcohol solvent (methanol, ethanol, propanol, isopropanol or buthanol) and the proportion used in the preparation of precursor solutions to obtain ZrO2–3 mol% Y2O3 sol–gel films are investigated. In particular, the effect of the aging process of the solutions on the porosity and critical thickness of the films is analysed. Implications for the preparation of zirconia sol–gel films by the dip-coating technique are also discussed.Other aspects of the process such as the aging of the solutions, the evolution of the dimensionless parameter J, the porosity, P, and the fully dense critical thickness, tcd, are also investigated and discussed. This allows one to understand the behaviour of the precursor solutions, and to obtain dense coatings and crack-free films. The results reveal a significant influence of the alcohol used as the main solvent in the first densification stages of the films (100 °C–500 °C). Likewise, the type and amount of alcohol used also notably influence the aging process of the solution, the porosity and the fully dense critical thickness finally obtained with each solution.