| Laser Post-Treatment of Plasma Sprayed Al2O3-Cr2O3 Coatings | ||
| Dr. Pavel Ctibor1, Mr. Jiri Dubsky2, Blahoslav Kolman2, Mr. Alexandr Jancarek3 and Pavel Chraska2, 1Matertials Engineering, Institute of Plasma Physics, Za Slovankou 3, Praha, 182 00, Czech Republic, 2Materials Engineering, Institute of Plasma Physics, Za Slovankou 3, Praha, 182 00, Czech Republic, 3Department of Physical Electronics, Faculty of Nuclear Science and Engineering CTU, V Holesovickach 2, Praha, 180 00, Czech Republic
Chromia admixture to Alumina feedstock is used to block formation of γ-Al2O3 in plasma sprayed coatings. In this work a mechanical blend of Alumina-Chromia powders was used with the water stabilized plasma to make thick coatings. The resulting structure contained less of corundum type α-(Al,Cr)2O3 phase than for the fused feedstock. When additional post-treatment by a quasi-continuous laser was applied to the surface, amount of the corundum phase substantially increased. Careful examination of the treated surface revealed that the individual splats at and near the surface were fully remelted and the structure is formed by a homogeneous phase with no visible splat boundaries. Segregation of Chromium has been detected in the remelted zones which strongly affects the final properties of coatings. Fast melting and cooling of the ceramic material under certain spray conditions may result in formation of undesirable cracks between traces of individual passes of the laser beam. | ||