Microstructural Characteristics and Wear Performance of Plasma Sprayed Al_2O_3-13 wt. TiO_2 Coating on the Surface of Extrusion Wheel

摘要

The conventional Al2O3-13 wt. % TiO2composite ceramic coatings are fabricated by plasma spraying on the surface of extrusion wheel. The microstructure,morphology and phase compositions of the substrate and coating are investigated by using X-ray diffractometry( XRD),scanning electron microsopy( SEM) and energy dispersive spectroscopy( EDS). Moreover,the microhardness of the substrate and the coating are investigated using Vickers microhardness tester,the friction and wear behaviors of the substrate and the coating are investigated by using a block-on-ring tribometer under dry sliding conditions with the load of 245 N. The results show that bothγ-Al2O3and α-Al2O3phases are observed in the as-sprayed coatings,the mian phase is γ-Al2O3. There are white particulates Al2O3on its surface. The Al2O3-13 wt. % TiO2coating possesses higher microhardness which is about1018HV and 1. 6 times that of the substrate. The wear performance of coating is better than that of the substrate.In a practical application,the life of the extrusion wheel which is plasma sprayed Al2O3-13 wt. % TiO2coating on the surface is 1. 2 times that of the conventional extrusion wheel,and the life is about 330 h.