Effect of binary rare earth oxide on the properties of plasma sprayed Al₂O₃/TiO₂ coatings

Abstract

Purpose

This study systematically investigated the effect of the binary rare earth oxide of La₂O₃ and Sm₂O₃ on the properties of the Al₂O₃/TiO₂ (AT) coating, including phase transform, wear behavior, etc.

Design/methodology/approach

AT coatings mixed with different components of binary rare earth oxides of La₂O₃ and Sm₂O₃ are prepared by atmospheric plasma spraying. The adhesion strength, micro-hardness, phase transition and tribological behavior of coatings are systematically investigated.

Findings

The X-ray diffraction (XRD) analysis shows that phase transformation is obvious after spraying, and a-Al₂O₃ is almost translated into γ-Al₂O₃ when La₂O₃ and Sm₂O₃ are doped together. Meanwhile, solid solution generated between rare earth oxide and Al₂O₃/TiO₂ coatings results in disappearance of TiO2 and rare earth oxide phase. The photos under the scanning electron microscope (SEM) indicate that binary rare earth oxide could increase the melting degree of powder and decrease porosity of coatings.The increasing of Sm₂O₃ rarely affect micro-hardness and adhesion strength, and the coating with 4 per cent Sm₂O₃ and 1 per cent La₂O₃ exhibits the best wear resistance and lowest friction coefficient among all the samples.

Originality/value

AT coatings mixed with different components of binary rare earth oxide of La₂O₃ and Sm₂O₃ are prepared by atmospheric plasma spraying. Binary rare earth oxide could increase the melting degree of powder and decrease porosity of AT coatings.

Citation

Ding, Q., Tian, B., Zhao, G., Wang, F., Li, H. and Shi, Y. (2017), "Effect of binary rare earth oxide on the properties of plasma sprayed Al₂O₃/TiO₂ coatings", Industrial Lubrication and Tribology, Vol. 69 No. 5, pp. 808-814. https://doi.org/10.1108/ILT-05-2016-0114