INFLUENCE OF INITIAL SURFACE CONDITION ON INTENSITY OF POROUS STRUCTURE FORMATION IN A METALLIC MATERIAL DURING LASER ACTION

Abstract

The influence of the initial surface condition on the intensity of porous structure formation in a metallic material during laser action has been determined. Two groups of samples were studied: Cu-Zn alloy with and without the oxide layer. Surface morphology of the samples has been researched using electron microscopy. The centre area of laser treatment zone on the surface of the samples is heated up to ≥500ºC not less than 180 s. At that, a porous structure with an irregular distribution of pores on the surface appears. Removing the oxide film by mechanical treatment leads to significant improvement of conditions of pore formation on the surface of the metal samples in the case of laser treatment. Consequently, a structure with a uniform pore distribution appears. After that, the temperature in the centre of the heat-affected zone increases to 500ºC for 12–20 s. This leads to a significant increase of pore formation intensity. In the case of using the obtained material as a catalyst, an increase of its specific surface area allows for the improvement of conditions for hetero-phase chemical and catalytic reactions, which increases the productivity of the catalytic actions.