Characteristics of the microstructures of alumina-based refractory materials treated with CO2 and diode lasers

Alumina-based refractory materials are known to possess good chemical attack resistance at high temperatures; thus, they are often used as Linings for furnaces and incinerators. However, there are still several components in such commercial alumina refractory materials which Limit their corrosion/erosion resistance, e.g., material inhomogeneity (existence of aggregates) and porosity. These promote corrosion attack and allow corrosive agents to penetrate and can possibly increase erosion damage. These properties, although recognised, are very difficult to overcome by current refractory manufacturing practice. Laser surface treatment is one novel method that has potential for eliminating porosity and producing a homogeneous surface layer. This paper describes microstructural and morphological characteristics of CO, and diode laser-treated 60% and 85% alumina refractory materials using SEM and optical microscopy. The research shows that a denser, uniform surface layer with solidification microstructures and which resists thermal shock, can be produced. The use of a high power diode laser for surface treatment of refractory materials is reported for the first time. (C) 1999 Published by Elsevier Science B.V. All rights reserved.