Abstract
The pulsed DC tungsten inert gas (TIG) method was employed to post-spray treat an electroconductive Al2O3–TiB2 coating by atmosphere plasma spraying (APS) Al2O3–30 wt-%TiB2 powder. The microstructure and mechanical properties of the coatings before and after treatment were comparatively investigated by scanning electron microscopy, laser scanning confocal microscopy, X-ray diffraction, microhardness tester and block on ring wear tester. It was detected that the treated coating presented a two layer structure consisting of the remelted zone and the sintered zone, which was comprised of TiB2 and single α-Al2O3; surface roughness of the treated coating exhibited a remarkable decrease while microhardness and wear resistance showed a significant increase. These experimental results could be ascribed to the effect of high heat input and discharge plasma during the pulsed DC TIG treating.
Acknowledgements
The authors gratefully acknowledge financial support provided Funding Project for Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality. Special thanks to Mr Li Guodong, an international welding engineer (International Institute of Welding), College of Material Science and Engineering, Beijing University of Technology (Beijing China), for his help during the experiments.