XeCl laser ablation of Al O –TiC ceramics

Al2O3–TiC ceramic composites are promising materials for micromechanical components. However, due to their hardness, brittleness and contraction during sintering, they are difficult to shape into high-accuracy parts using conventional forming techniques. Laser micromachining can be an alternative technique to shape this type of materials. Previous work using KrF ls248 nm.excimer lasers showed that micromachining was accompanied by the formation of a thin melted layer of resolidified material and, in certain conditions, a cone-like surface topography. This was explained by the different ablation behaviour of Al2O3 and TiC. To verify this assumption, Al2O3–TiC, Al2O3 and TiC ceramics were processed with a XeCl ls308 nm.excimer laser and their ablation behaviour was investigated. It was found that TiC has a higher ablation rate than Al2O3. The experimental results suggest that chemical reactions occur during processing of Al2O3–TiC in air and that cone formation can be due to the shielding of laser radiation by the resulting compounds. q2000 Elsevier Science B.V. All rights reserved.