Laser Micromachining of Ceramics

Laser surface processing of ceramics is an area of considerable technological importance for several structural, tribological, optical and electronic applications. The laser beam behaves as a heat source that induces a temperature rise on the surface and within the bulk of the material. Depending on laser parameters and material characteristics, lasers can be used for fabricating microholes at designated locations, for cutting, scribing, for surface modifications In this work different types of laser processing of ceramics are analysed. A pulsed KrF excimer laser was used for surface treatment, with the aim of tailoring the surface roughness of conventional ceramics such as Alumina, Silicon carbide. Ultrarefractory non oxide ceramics such as hafnium and zirconium carbides were treated to obtain a surface texturing using a femtosecond laser. A pulsed CO2 laser was used to form a micro-holes texture on silicon carbide materials. The relationships between hole dimensions and laser processing conditions (pulse duration, laser power, lens focal length) were studied. A series of tests was carried out to attempt a process optimization. The possibility of producing a regular array of microholes was demonstrated. During laser processing, the high temperature reached at the sample surface cause the formation of a heat affected zone which is influenced by both laser parameters and material characteristics. Strong microstructural modifications are observed in the treated areas such as melting, vaporization and resolidification, formation of droplets, grain growth and crack formation