| Abstract [eng] |
Using atmospheric plasma spraying alumina and alumina-graphite coatings were deposited. Aim of this work was to investigate an average plasma jet temperature and graphite concentration influence on coatings morphology, crystallography and tribological properties. Results showed that an increase of plasma spraying power from ~37 kW to 45 kW, enhanced the mean plasma jet temperature from 3550 K to 3700 K. Scanning electron microscopy images revealed rough, however, undamaged and well-coated surface. Reduction in average linear and quadratic surface roughness was obtained with an increase of torch power (plasma temperature) or introduction of graphite powders into alumina coatings. Energy dispersive spectroscopy revealed mismatch between the carbon content in the coatings and graphite concentration in feedstock alumina powders. X-Ray diffraction revealed that an alumina powders consisted from α-Al2O3 and β-Al2O3 phases, meanwhile the additional γ-Al2O3 phase was observed in the deposited alumina and alumina-graphite coatings. Tribological investigation showed an appearance of the tribolayer on the surfaces of the alumina-graphite coatings. However, the formed tribolayer on the surface was non-homogenous and noncontinuous. The deposited Al2O3 and Al2O3-graphite coatings demonstrated normalized wear rate up to 10 times lower compared to the steel surface. |
