Ablation Characteristics of Alumina and Zirconia Ceramics on Ultra-short Pulsed Laser Machining

Ultra-short pulsed laser manufacturing gives a unique route to ablate hard-to-machine materials and enables little thermal impact. A comparative study on an alumina-toughened zirconia (ATZ) composite and pure alumina is presented. Singleand multi-pulse ablation of 1030nm and 515nm wavelength with sub picosecond pulses reveal an abrupt increase of the material removal rate. Pockets with 5μm beam distance and 15 layers rotated by 23° are generated to attain the multi-pulse ablation rate. The threshold fluence gives 0.1J/cm2 and 0.11J/cm2 for green wavelength and the ATZ and alumina, respectively. Single pulse ablation with 7J/cm2 energy density point to the sharp ablation limit and an electron microscopy assessment reveals a step-like behavior. Subsequent Raman spectroscopy studies prove the persistence of the tetragonal morphology of zirconia. These findings enable laser manufacturing of microstructures on ceramic specimen with a 2.5D and quasi-tangential strategy.