Surface texturing of sialon ceramic by femtosecond pulsed laser

Abstract

Femtosecond laser surface micromachining is a technique in which an ultrashort pulse laser beam is focused to dimensions of a few microns inside or on the surface of the substrate. In this paper, surface texture transformation behaviour of the SiAlONSi(sub3)N(sub4) ceramic using the Ti: Sapphire Femtosecond laser system was investigated. Parametric analysis was conducted using surface drilling, unidirectional and cross-hatching machining procedures performed on the substrate at a varied power and scanning speeds. A linear relation was observed on the microtexturing dimensions and roughness with respect to laser powers and this provided optimum micromachining mechanism at the chosen power of 0.25 W. Two roughness regimes characterised by periodicity and sharp valleys were observed at low pulse overlap and high pulse overlap respectively. Due to the complexity of the surface transformation chemistry, the necessity of a complementary cleaning procedure to remove the silicates retained by the laser treated surface was emphasised.