Nanoceramic caotings produced by laser treatment

Abstract

Sol–gel derived thin nanoceramic layers of TiO2, SiO2, 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 a specially designed lens. The specimen is placed where the magnetic field is largest and a maximum resolving power of 1·5 nm at 3 kV accelerating voltage could be attained. The melt spun layers were treated by either furnace or laser curing, which appeared to dictate the final morphologies of the layers to a large extent. Grain growth was present in furnace cured and laser cured layers and the activation energy for grain growth of these layers was determined. Homogeneous dense layers were obtained if the parameters in the curing process were selected appropriately. If the parameters were chosen incorrectly, severely debonded layers were obtained. Preheating the layers resulted in less blister formation. The mechanisms which may cause the layers to fail are examined in more detail.