Microstructural characteristics of Al2O3-based refractory containing ZrO2 induced by CO2 laser melting

In this study, an Al2O3-based refractory containing ZrO2 was treated by a CO2 laser surface melting aiming at improving its surface density and modifying the corresponding microstructure, which were considered to be important factors influencing the erosion resistance of refractory materials. The microstructure and phase structure characteristics of the refractory induced by the laser beam have been investigated by scanning transmission microscopy incorporating energy-dispersive X-ray technique and X-ray diffraction analysis. The laser scanning velocity had a significant influence on the microquality of the laser-molten tracks. Laser treatment at a lower scanning velocity of 4 mm s 1 could result in severe evaporation to some lower evaporating point phases, which could result in more cracks and pores, rougher surface. Increasing the scanning velocity up to 12 mm s 1 alleviated the evaporation phenomenon and reduced the drawbacks above to a great extent. After laser surface melting, the microstructure was changed into a fine and dense hypoeutectic structure and the phase m-ZrO2 was uniformly dispersed into the dendrite instead of the non-uniform particle-like shape in the as-received refractory, the dominant phase was changed from Al6Si2O13 to a-Al2O3 while a small amount of high temperature phase c-ZrO2 was retained at the room temperature. # 2003 Elsevier B.V. All rights reserved