Pore Formation and Aluminum Precipitation during Laser Alumina Reduction in Hydrogen Atmosphere

Abstract

Laser alumina reduction using a kW-class CW laser has been studied for the goal of In-Situ Resource Utilization of lunar resources. When an alumina rod is irradiated by a high intensity laser, aluminum particles are precipitated on its surface. In this study, a rod was irradiated in hydrogen atmosphere to increase aluminum precipitation. As a result, pores were created at the molten edge of alumina rod, unlike in the argon atmosphere, and aluminum particles were precipitated at high density on the surface of these pores. This is thought to be the result of hydrogen dissolving into liquid alumina, reacting with oxygen, and going out as water vapor. In addition, by irradiating the moving alumina surface, pores with aluminum precipitation were generated over a large area of the surface or inside of the rod, and precipitation per laser output energy of 12 μg/kJ was achieved.