Reactive Laser Additive Manufacturing of Multifunctional Carbide and Nitride Ceramics

Non-oxides ceramics (carbides, nitrides, and borides) are optimal materials for extreme environments which include prolonged exposure to high-temperatures, chemically reactive conditions, radiation, stress, and mechanical wear. Applications of non-oxides range from electronics substrates, high-temperature MEMS devices, nuclear and electrochemical energy generation, thermal protection systems, and machinery/tooling. However, non-oxide components are typically restricted to simple geometries or coating materials due to challenges imposed by traditional ceramic processing methods. To date, processing non-oxides with laser-based additive manufacturing (AM) has not been fully realized due to a variety of obstacles: high laser energy densities are required to overcome slow diffusion rates, yet localized laser exposure induces decomposition or microcracking when a ceramics thermal capabilities are exceeded. To circumvent such issues, we utilize an alternative technique for AM non-oxide processing by synthesizing the ceramic material in-situ, during part formation. Specifically, we demonstrate that by employing laser-induced gas-solid reactions, reaction-bonded, near net-shaped ceramics may be fabricated using AM compatible techniques. Although this method necessitates the consideration of additional processing variables (e.g. gas-composition, reaction kinetics, precursor morphology, etc.), we demonstrate how this reactive approach may be viable for the production of unique carbide, nitride, and composite materials (including SiC, Si3N4, TiN, HfC) that were not readily accessible using traditional additive techniques.