Preparation and characterization of ZrO2/Y2O3/Al2O3-based microstructured multilayer sol–gel coatings

In this work several microstructured multilayer coatings with improved surface properties based on ZrO2/Y2O3/ Al2O3 systems were produced and characterized through a suitable combination of the sol-gel method with dip coating, studying the influence of the Al2O3 load (0-20%) on the coating characteristics. It was found that even at high alumina percentages, transparent, stable and suitable sols were obtained as a result of an optimized preparation method developed by our group. Sols sintetized allowed the preparation of high quality ZrO2/Y2O3/Al2O3-based microstructured multilayer sol-gel coatings. A noteworthy rise of Guglielmi and Zenezini's adimensional flow parameter (J) was observed by increasing the Al2O3 load, suggesting that the quantity of material deposited onto a substrate was also increased. This result also corroborates a slight increase of films thicknesses after heat treatments. In addition, an increase on the coatings porosity was revealed by increasing the alumina content that could probably affect the final properties of protective coatings.