Formation of Foamy Coatings by Laser Ablation of Glass-ceramic Substrates in the Nanosecond Regime Substrate - Temperature and Wavelength Dependence

Abstract

A study of the formation mechanisms of foamy coatings on the surface of glass-ceramic substrates produced by laser ablation is presented. Three laser systems emitting at 1064, 532 and 355 nm with pulse-widths in the nanosecond range were used. In the NIR range the formation of the coating is only possible when the temperature of the surface is higher than 300 ºC. In this case, the generation is related to an increase of the layer in liquid-phase produced in the interaction zone. However, when the sample is machined at 532 or 355 nm, it is not necessary to heat the whole surface to be processed. In this case, the local temperature and the pressure exerted over the interaction zone produce the generation of this coating, obtaining the layer at room temperature. Furthermore, the coating can be produced at higher speeds. In this way, it is possible to reduce the energetic cost improving the efficiency of the process.Morphology, microstructure, composition and thermal properties of the layer are described.

Microstructural and Wear Behavior Characterization of Porous Layers Produced by Pulsed Laser Irradiation in Glass-Ceramics Substrates

“…The possibility of producing porous layers on the surface of glass-ceramic substrates has been demonstrated when the substrate is machined by means of pulsed lasers in the nanosecond range [ 22 , 23 ]. Laser ablation in the nanosecond range is a photothermal-mechanical process so that the material is removed by the thermal mechanisms activated by the laser beam.…”

“…In this case, the formation mechanisms are in relation with the variation of the absorbance of the glass-ceramic substrate with the wavelength. The absorbance of the glass-ceramics substrate decreases with the wavelength [ 23 ]. In particular, the optical absorption coefficients, α, for 355 and 532 nm are 62.13 and 28.37 cm −1 , 17 and 8 times greater than for 1064 nm, the value of which is 3.52 cm −1 .…”

“…As material, a glass-ceramic substrate, Ceran Suprema ® , manufactured by Schott was used. Their chemical composition and structure were fully characterized by the authors in a previous paper [ 23 ]. Its main properties are shown in Table 1 .…”

“…Furthermore, laser machining and surface modification of these materials are very interesting for functional purposes in industrial applications since these modifications may be applied as thermal-barriers, heat-conductor tracks, inclusion of thermal sensors, etc. [ 20 , 21 , 22 , 23 ].…”

“…In previous works, the formation mechanisms for generating porous layers by pulsed laser irradiation on the surface of a glass-ceramic substrate in function of the laser wavelength and substrate temperature in the nanosecond range were studied [ 22 , 23 ]. In this work we present the wear behavior characterization of this porous layer in order to determine the friction coefficient (COF) and the wear resistance.…”