Abstract:

Laser Assisted Microwave Plasma Processing (LAMPP)1 is a new method for direct sintering and melting a ceramic coating on top of a high temperature resistant ceramic substrate. A spatially well-confined laser beam is used to ignite and localize a microwave plasma plum at the surface of the substrate and melt a ceramic powder deposited by slip casting to form a dense coating. The phenomena underlying ignition and sustainment of the plasma are described with respect to Laser Induced Brake-Down and Microwave Induced Brake-Down, respectively. Refractory ceramics used in glass tanks are prone to corrosion by the glass melt. The paper presents results on corrosion resistance of refractory zirconia-mullite ceramics (so called AZS ceramic) with a dense 8Y-ZrO2-coating in E-glass melts as compared to non-coated ones, at temperature of 1300 – 1500 °C. The role of the compositional gradient is discussed with respect to known glass corrosion mechanisms and the rapid solidification of the ceramic melt upon processing. Different microstructures are obtained depending upon the number of individual layers of Zirconia deposited onto the surface of the refractory. Coatings of up to mm thickness can be deposited by LAMPP, with a very good bonding and interphase containing interlocked Zirconia dendrites. Such microstructure retards the corrosion of the ceramic significantly.