Laser-induced surface crystallization of eutectic composition glass

Reference Presenter Authors
11-023 Ângela Santana Nunes Nunes, .S.(Federal University of São Carlos); Andreeta, M.R.(Federal University of São Carlos); In the last decade, laser radiation applied to materials processing has become an important tool for new devices development, as well as to improve several production processes, such as drilling, cutting and welding processes, sintering of oxide ceramics, surface heat treatment, directional solidification applied to the growth of single crystal fibers and texturization of crystalline compounds. The characteristics that make the laser radiation attractive for these purposes are coherence and collimation, which allow adjusting the energy distribution with conventional optical elements, as well as locating the source energy away from the preparation process. The systematic study of laser-induced surface crystallization was first studied by Mai [1] for the glass system Al2O3-Li2O-SiO2. The mechanism of surface modification depends mainly on the composition of the sample, the power of the laser and the time of radiation exposure. The objective of the present work is the analysis of the microstructure obtained after a CO2 laser surface heat-treatment of a glass in its eutectic composition for the system LiO2.SiO2 - CaO.SiO2. The glass and the laser-induced surface crystallization of parallel lines on the glass surface were characterized using differential scanning calorimetry, X-ray diffraction, scanning electron microscopy and optical microscopy. Results show that it is possible to achieve a well defined crystallization of different phases in the region without cracks. As expected, the microstructure showed to be dependent on the line scanning speed and laser power. A discussion based on the Jackson-Hunt theory will be presented. Acknowlegments to FAPESP (2013/07793-6) and CNPq (120348/2015-2).

[1] - Mai, C. "Surface nucleation and crystallization by laser in TiO2 and ZrO2 doped SiO2-Al2O3-Li2O glass", Supplement to "Rivista della Stazione Sperimentale del Vetro", vol. XXIII, 1993.
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