Directionally solidified fabrication in planar geometry of Al2O3-Er3Al5O12 eutectic composite for thermophotovoltaic devices

In this work Al2O3-Er3Al5O12 eutectic composite was manufactured in planar geometry departing from eutectic particles both produced by directional solidification using a CO2 laser system at rates of 180 and 720 mm/h. Microstructure and mechanical properties were investigated as a function of the growth rate. Homogeneous and interpenetrated microstructure was found with phase size strongly dependent on the growth rate, decreasing when the processing rate was increased. Thermal emission of eutectic composites was studied in function of thermal excitation by using CO2 laser radiation as a heating source. An intense narrow emission band at 1.55 µm matching with the sensitive region of the InGaAs photoconverter and a low emission band at 1 µm were obtained. Features of thermal emission bands were correlated with collecting angle, microstructure and laser power, and compared to those obtained from departing eutectic particles