Nano- and microcomposite Al2O3-Y2O3 coatings produced by sol-gel process

Nano- and microcomposite Al2O3-Y2O3 coatings have been deposited on Fe-Cr-Mo alloy substrates using sol-gel composite coating technology. The processes include dipping samples in a sol-gel solution dispersed with fine ceramic powders, which is prepared by high-energy ball milling. High-resolution microscopy (FE-SEM) analyses show that the coating is composed of composite particle clusters with an average diameter of 1 mm, and the coating is relatively dense without cracking during drying and sintering stages. XRD analyses show that the oxide coating is mainly composed of alpha-Al2O3 and gamma-Al2O3. The oxidation tests performed in air at 600 degrees C show that the coatings possess much improved resistance to high temperature oxidation and scale spallation. It is believed that the nano-structured composite particles and reactive elements are integrated into the coatings, which played an important role in improving the aggregation of nanoparticles and the production of cracks.