Investigation on the Surface Structure and Tribological Characterization of 10 wt.% ZrO ₂ -Reinforced Alumina Prepared by Flame Spray Coating

Abstract

<div>In this study, we have investigated the microstructural characteristics, the mechanical properties, and the dry sliding wear behavior of a ceramic coating consisting of zirconia (ZrO<sub>2</sub>) and alumina (Al<sub>2</sub>O<sub>3</sub>) deposited by flame spraying. A series of wear tests were carried out under a variety of loads and at two different sliding speeds. The evaluation included an examination of the coating microstructure, microhardness, coefficient of friction (COF), and wear resistance of the flame-sprayed coating. The results showed that the coatings had a perfectly structured micro-architecture and were metallurgically bonded to the substrate. The Al<sub>2</sub>O<sub>3</sub> coating exhibited a fine granular structure with pores and oxides. The microstructure of Al<sub>2</sub>O<sub>3</sub>-10 wt.% ZrO<sub>2</sub>, on the other hand, showed a blocky structure with a uniform distribution of ZrO<sub>2</sub> inclusions in the composite coating. X-ray diffraction (XDR) results showed that the phases in both coatings were predominantly α-Al<sub>2</sub>O<sub>3</sub> with a minor presence of γ-Al<sub>2</sub>O<sub>3</sub>. However, in addition to residual ZrO<sub>2</sub> in the tetragonal phase, the ZrO<sub>2</sub>-Al<sub>2</sub>O<sub>3</sub> coating showed a predominance of ZrO<sub>2</sub> in the monoclinic structure. To elucidate the intricacies of the wear mechanism and the characteristics of the wear debris, a comprehensive analysis of the wear performance of flame-sprayed ceramic coatings was carried out.</div>