STTR Phase I: Rapid Investment Casting of Superalloys Using Microwave Technology

The broader impact/commercial potential of this Small Business Technology Transfer Research (STTR) Phase I project is aligned with revolutionizing the metal casting industry by demonstrating a novel rapid and versatile investment casting system. This all inclusive unit is based on a hybrid microwave heating technology which permits direct irradiation of the casting mold and metal melt, which results in low energy consumption and tight control of the melting/casting processes. This revolutionary system will permit any size business to design and fabricate low volume metal parts, with complex geometries of any metal composition (from low-temperature metals to high-temperature superalloys). By coupling this technology with 3D polymer printing technology to form the mold core, near-net shaped parts with complex geometries may go from computer design to a casted part in a matter of a few days (compared to the typical multi-week delivery for traditional investment casting). These attributes address many of the current needs of the modern commercial market, which requires rapid turnaround of new products with shorter product development time. In addition, the future of advanced manufacturing in the US will be dependent upon small businesses responding to the market with small quantity, but high-value and high-quality parts. The intellectual merit of this project will be based on the investigation of a furnace design which will utilize microwave energy to rapidly melt high-temperature metal alloys for the casting of complex parts within an investment casting process. The investigation will also focus on early thermal steps within the investment casting process, in order to reduce processing time and energy consumption, and thus lead to a savings in cost and emissions. Microwave heating has been demonstrated for a variety of food products and inorganic powders, but there are little to no reports on the use of microwave energy to melt and cast metals, especially high-temperature alloys such as Ni- and Ti-based alloys. This work will investigate this novel melting technology. The work will show the relation between the method of microwave coupling, level of superheating, and hybrid quenching technique (through selective microwave coupling within the investment mold) on the microstructure and mechanical properties of the resultant metal parts. This information will lead to the design of a final microwave-based metal melter/caster, which will provide businesses (from small machine shops to larger foundries) the ability to rapidly cast a variety of complex-shaped, low- and high-temperature alloys in the same unit.