Characterization and compositional study of fibre laser processed engineering ceramics

Surface treatment by means of a CO2 laser and a fibre laser radiation was conducted on cold isostatic pressed (CIP) silicon nitride (Si3N4) and zirconia (ZrO2) engineering ceramics to observe changes in their characteristics, surface integrity, microstructure and composition. Scanning electron microscopy (SEM) was used to observe the integrity prior to and after laser processing. Energy dispersive X-ray (EDX) analysis was employed to detect surface modifications of the ceramics composition for both virgin (untreated) and laser treated surfaces. Thereafter, thermal gravometric-differential thermal analysis (TG-DTA) was employed to evaluate the behaviour of the ceramics under thermal shocking during the laser/material interaction. Effect of surface oxidation particularly with Si3N4 and a degree of compositional change during its phase transformation as the Si3N4 transformed to silicon carbon dioxide (Si3CO2) and in some area as silicon oxide (Si3O2).