Papers by Author: F. Quintero

Abstract: There are many manufacturing techniques to form metallic particles with certain size and properties. The laser heating method has been successfully applied to generate metallic particles when a supersonic gas flow is assisting this process. The metallic target is heated, melted and vaporised and micro-particles are carried away by a gas flow stream. The high-velocity gas is used to solidificate molten particles and to condensate the metallic vapour resulting in the formation of fine particles. Several attempts were carried out for the production of metallic particles by laser supersonic heating method, obtaining spherical micro-particles (1- 50 "m) of copper, steel, or aluminium. This work presents the application of this method to generate particles from fish bone, in order to obtain a material with a composition close to the inorganic part of the bones. A pulsed Nd:YAG laser has been used to obtain calcium phosphate micro- and nanoparticles. Microparticles size ranges from 10 to 100"m, whereas the nanoparticles have diameters as small as 2 nm. High resolution transmission electron microscopy (HRTEM) allowed us to identify the nanoparticles as whitlockite.

Abstract: Following previous work focused on the laser processing of natural stones, we present in this paper the results of the study carried out to verify the feasibility of the lasers to drill slate tiles and granite slabs. The two types of laser equipments most used in the industry (CO2 and Nd:YAG) have been used to fulfil a comparative study. The influence of different parameters involved in the process, such as, average power, stand-off distance, and assist gas pressure, have been studied to characterise the drilled holes size and geometry. Results from the different tests show that it is possible to obtain holes according to the required dimensions at reasonable powers ( i.e. no more than 400 W for the Nd:YAG and 1 kW for the CO2 laser). Holes up to 2 mm can be achieved in a very reduced time without breaking of the stone plates. The overall results show that the laser drilling technique could be an alternative to mechanical drilling of plates of natural stones to be used in ventilated façades or for roof fixation.