Novel Additive Manufacturing of Ceramic Components via Reaction Bonding
Graduate Student: Zachary Ahmad
Laser-powder bed fusion (L-PBF) is an additive manufacturing technique that enables the creation of dense, net-shape or near-net shape structures. However, applying L-PBF to high-temperature materials presents challenges such as thermal shock, weak densification, and limited light absorbance. To address these issues, a collaboration between the Faber Group and NASA's Jet Propulsion Laboratory (JPL) has developed a new method that combines L-PBF with reaction bonding. This innovative process uses a powder bed consisting of aluminum oxide, an aluminum alloy, and zirconium oxide. The aluminum alloy melts at about 660°C during laser treatment, which is much lower than its oxide counterpart (2072°C), resulting in composite powder fusion. This lower temperature prevents thermal shock while maintaining high light absorbance. In a post-L-PBF step, reaction bonding transforms the aluminum into aluminum oxide, increasing its volume to fill the reaction-bonded solid.
Our primary objective is to demonstrate that this new method can produce near-theoretical density, non-magnetic structures with near-net-shape tolerances. As part of this effort, we aim to fabricate a magnetometer core/housing for JPL based on a flight design that achieves over 99% density after printing and post-processing, features near-net-shape geometry, and exhibits magnetic susceptibility comparable to commercial zirconia/alumina materials. We are currently studying the kinetics of aluminum oxide reaction bonding and its thermal analysis to optimize JPL's L-BFT additive manufacturing protocols when combined with reaction bonding. We are also characterizing the physical, chemical, and mechanical behavior of L-PBF/reaction-bonded materials to establish property-processing relationships in aluminum oxide-based systems. The project will eventually expand to include alternative oxides and non-oxide systems as secondary phases, along with reinforcing the systems with platelets or fibers to improve thermo-mechanical properties.
Owing to the nature of L-PBF processing systems, reinforcements can be strategically placed within components to meet NASA’s specific mechanical needs, such as enhanced fracture toughness or as part of sampling systems like coring and drilling tools. This ability to create complex, geometrically intricate ceramic components with minimal magnetic response will benefit numerous JPL missions, such as those that faced challenges related to the magnetic cleanliness of their magnetometer materials, such as the Europa Clipper and Psyche missions. Furthermore, this study provides the foundation for broader ceramic composite exploration and development, while providing a blueprint for better thermo-mechanical integration of ceramics with space craft componentry.
a) Scanning electron micrograph of reaction-bonded aluminum oxide (RBAO) and zirconium oxide after firing. b) Reaction-bonding example process with resulting di-metal pillar.