Effects of aluminum phosphate sealant containing Al2O3 nanoparticles on the hardness and wear resistance of the Al2O3-TiO2 plasma sprayed coating

Abstract

In the present study, Al₂O₃-40% TiO₂ composite coatings were fabricated on CT3 steel substrate by plasma spraying technique. The coatings were sealed with aluminum phosphate solution contained 5 wt.% Al₂O₃ nanoparticles and then heat treated at 400^oC. The permeability of aluminum phosphate solution, phase composition, structure morphology, microhardness and wear resistance of the coating were studied. The study results phase composition of the coatings showed that the coatings were composed γ-Al₂O₃ and Al₂TiO₅ phase. The compounds AlPO₄ and Al(PO₃)₃ were found in the coating sealed with aluminum phosphate. The presence of Al₂O₃ nanoparticles was increased the permeability of the aluminum phosphate solution into the coating. The coatings sealed  with aluminum phosphate contained Al₂O₃ nanoparticles have lower density, higher hardness and wear resistance higher than the coating sealed with aluminum phosphate uncontain Al₂O₃ nanoparticles and the unsealed coating.