Preparation of Plasma Sprayed Al2O3/TiO2 Composite Powder by Sol-Gel Method

Owing to poor liquidity and low density of traditional thermal spraying powder, the performance of the as-sprayed coating is poor and unreliable. Using aluminum isopropoxide and tetrabutyl titanate as raw materials, and ethanol/water as solvent, AT-13 precursor thermal spraying powder was prepared by sol-gel method and spray drying. TG-DSC, XRD, FESEM, and Holzer flowmeter were used to study the reaction mechanism, the phase composition and microstructure of the powder. Vickers hardness of the coatings were also analyzed and compared by FESEM-EDS. The results show that the spherical precursor powder is composed by Ti(OH)(4) and AlOOH with a diameter of about 40 mu m after spray drying. Compared with the commercial AT-13 powder, the flowability of the precursor powder is better for 43 s/50 g. The coating parpared by precursor powder appears smooth surface, uniform element distribution and stable mechanical performance. Its average microhardness reaches 873.8 HV0.3 and the wear weight loss is 1/3 less than that of the agglomerated powder coating.