TSE: Collaborative Research: Environmentally Benign Manufacturing - Casting by Design

Rensselaer Polytechnic Institute, Troy NY

Investigators

Abstract

This National Science Foundation and Environmental Protection Agency Technologies for a Sustainable Environment project proposes a new technology to enable continuous casting of molten metals, in a single step, to the specifications of the designer. Bessemer's vision (1865) of solidifying raw material directly into final product, without downstream processing steps (rolling, annealing), may now be realized for thin flat product, to marked environmental advantage. To cast aluminum foil, e.g., in a single step, would reduce CO2 emissions to the atmosphere by 250,000 tons per year, in the US alone. Every kilogram of aluminum saved in reducing manufacturing waste translates into electricity saved at the energy-hungry smelter. The technology is based on controlling length scales previously inaccessible to control. The idea is a marriage between laser and single-roll spin casting technologies. The laser offers a unique way to bring energy into the zone of contact between molten metal and substrate. The contact zone is a region of adverse conditions, generally inhospitable to mechanical intrusion. Successful casting by design, or tunable casting, will use laser energy to manipulate product quality. One approach is to condition the substrate by imposing thermal gradients before the contact zone. Grey-scales in ink-jet printing are produced by the spacing and arrangements of ink dots of the same size. In much the same way, the proposed gradients will be established with arrangements and spacing of hot spots. Laser heating will induce the hot spots at fine scales. This project will have significant societal benefits in reducing environmental impact and energy consumption, as well as providing improved scaled-down processing requirements for industry.