An investigation on the properties of YSZ/Al2O3 nanocomposite coatings on Inconel by electrophoretic deposition

Abstract

Nanostructure yttria-stabilized zirconia (nano-YSZ) /Al2O3 composite coatings were deposited on Inconel super-alloy substrates by electrophoretic deposition. Aluminum and nano-YSZ particles were utilized for reaction bonding at high temperatures. After aluminum oxidation at 650℃, sintering process was carried out at temperature ranges of 1100–1250℃. It was found that the presence of aluminum in the green coatings improves bonding and also compensates for the coatings’ volume shrinkage during sintering. The average crystallite sizes for all sintering temperatures were laid on a nanometric scale. Crystallite sizes of various YSZ/Al2O3 nanocomposite coatings were calculated via Scherer’s formula and the measures were in a reasonable agreement with the field-emission scanning electron microscopic results. The average grain size increased from 52.4 nm at 1100℃ for YSZ, to 68.3 nm at 1250℃ for YSZ/Al2O3 nanocomposite coatings. The nanocomposite coatings, which sintered at 1250℃ for 4 h exhibited an optimized self-crack healing capacity with lesser microcrack content.