Comparison of Dry Sliding Tribological Behavior of Nanostructured Al2O3–13 wt% TiO2 Coatings Prepared by High-Efficiency Supersonic Plasma Spraying and Atmospheric Plasma Spraying

Abstract

Plasma sprayed ceramic coatings have been widely used in friction and wear protection of mechanical parts. In this paper, the nanostructured Al2O3-13 wt.% TiO2 coatings were prepared by high-efficiency supersonic plasma spraying (HESP) and atmospheric plasma spraying (APS) respectively. The surface and section morphology of the coatings were observed by scanning electron microscopy (SEM). The phase composition of the coatings was analyzed by X-ray diffraction (XRD). The dry sliding friction properties of the coatings were tested on UMT-3 friction and wear testing machine. The results show that after plasma spraying, a large amount of γ-Al2O3 phase appears, while TiO2 phase almost disappears in the coatings; compared with APS, the coatings sprayed by HESP have fewer defects and better coating quality; under dry friction condition, the steady-state friction coefficient of the coatings sprayed by HESP and APS all decreases with the increase of load, and the wear volume all increases with the increase of load. When the load is more than 40 N, wear volume of the coatings sprayed by APS is basically twice that of HESP; the wear mechanism of the coatings sprayed by HESP is the laminar cracking, peeling off and the adhesive wear.

Dry sliding wear behavior of hard-chrome and zinc-phosphate conversion coatings on steel substrates

“…are widely used to improve tribological properties of steel. 4–14 Out of these available methods, coating or deposition of a thin surface layer proves to be beneficial for applications where dimensional accuracy is a constraint. Hard-chrome plating and chemical phosphate conversion coating are suitable methods to enhance the wear resistance of steel.…”