Dual laser beam modification of high alumina ceramics

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Abstract
Alumina-based refractory materials are extensively used in high-temperature applications, such as linings in waste incinerators. A significant problem affecting the performance of these materials is the presence of porosity and material inhomogeneity, which promote molten slag corrosion and chemical degradation. Single laser energy sources have been used in the past to densify and homogenize the surface of such ceramics. A major difficulty during laser surface treatment of brittle materials, such as ceramics, is solidification cracking due to very large temperature gradients that are developed during processing. The aim of the work presented in this article is to investigate the surface modification of 60% alumina refractory ceramics by applying two laser sources simultaneously in order to control the thermal gradients and cooling rates so that crack formation can be eliminated. The dual laser beam modified surfaces have been analyzed using optical and scanning electron microscopy, as well as electron probe microanalysis, and compared with those of single laser beam treated samples.