Papers by Author: G. Zak

Abstract: A better understanding of the optical properties of plastics at IR wavelengths is important for optimizing the laser transmission welding process. In this study, the optical properties, scattering and absorbance, of polypropylene (PP), polycarbonate (PC) and polyamide (PA) were investigated by using spectrophotometer with integrating sphere. The influence of thickness, surface roughness and filler content on optical properties of thermoplastics was evaluated. The results could contribute to a better understanding of the process itself and to success in the practical applications.

Abstract: This investigation considers the development of microchannel reactors with catalystcoated walls for fuel-processing applications. In particular, the focus is to study the possibility of direct etching of microchannels into aluminum and alumina using a solid-state UV laser. Microchannels of a scale between 10μm-200μm across and 10μm-100μm have been ablated into aluminum and alumina bases. It was found that single scans resulted in narrow channels (20μm- 30μm in width) with shapes described by a Gaussian-like distribution. Multiple scans allowed fabrication of channels with a larger width, but of a similar depth. The surface quality was observed to be quite uneven, with roughness on the order of 1μm-2μm.