Abstract:
The 976 nm Ytterbium fiber laser (CW) was exposed on ZrC, TiC and TiC+TiB2 (composite) samples under various experimental conditions to study the formation of oxide layers and surface morphologies. The laser exhibit high absorption on the surfaces of transition metal carbides and borides. The generation of longitudinal, lateral and transverse stresses was also calculated to evaluate the difference in cracking behavior of these samples at respective energy densities. The samples were LASER treated at various power and speeds under argon flow of 2.8 exp -4 m3/s (16.8 liter/ minute), corresponding to approximately 10% oxygen conditions. All the powders were Hot Isostatic Pressure sintered under same conditions to produce standard 5 × 15 mm pellets. The samples were polished to produce standard surface roughness of 1µm. The XRD, SEM and TEM were used to characterize the oxide layers formed by the laser treatment. The highly crystalline TiO2 layer with better adherence than ZrO2 was observed. The amorphous oxide layer with nano-crystalline regions was observed on the composite substrate under TEM. The two stage laser treatment was also conducted on ZrC substrate exhibiting broadening of peaks in the XRD spectrum.
