Cracks in Nano-Ceramic thin Layers Produced by Laser Treatments

Abstract

AbstractSol-gel derived thin nano-ceramic layers of TiO2 and Al2O3 are studied using scanning electron microscopy to reveal the microstructure and morphologies of the layers. The low-voltage scanning electron microscope with a field emission gun is equipped with an especially designed lens, where the specimen is placed at the location where the magnetic field is the largest. In such a way a maximum resolving power could be attained of 1.5 nm at 3kV accelerating voltage. The melt-spun layers were treated differently afterwards, i.e. by furnace and by laser curing. These heat treatments appeared to dictate the final morphologies of the layers to a large extent. Grain growth is observed for the furnace as well as the laser cured layers. The activation energy for grain growth of these layers is determined. Homogeneous dense layers may be obtained if the parameters in the curing process are selected adequately. If the parameters are chosen incorrectly, severely debonded layers may be obtained. Pre-heating the layers resulted in less blister formation. The mechanisms which may cause the layers to fail were examined in more detail.