Thermal History Mapping in Powder Bed Laser Sintering at the Micrometer Scale

A thermal sensor was used to better understand parameters which influenced the interaction between a laser beam and a 0.5% Mn-doped ZnAl_2.2O₄ material, especially the laser defocusing parameter. The optical properties of the material depend on whether the Mn²⁺ ions occupy octahedral and/or tetrahedral sites depending on thermal history. A screen printing process is performed to obtain material thin films. Laser irradiation of the films was carried out (patterning 1 cm length single laser track) with different z defocusing heights. Luminescence properties around laser tracks led to the thermal history determination at the micrometer scale. It was shown that spatial thermal gradients defined at the micrometer scale perpendicularly to the borders of the laser tracks could be semiquantified for different z conditions. Laser defocusing leads to decrease thermal gradients as confirmed by thermal modeling studies.