Selective laser sintering in reactive atmospheres: Towards in-situ synthesis of net-shaped carbide and nitride ceramics

Selective laser reaction sintering techniques (SLRS) were investigated to produce near net-shape non-oxide ceramic materials that previously incompatible with powder-bed fusion additive manufacturing (AM) methodologies. Specifically, reaction-bonded layers of carbide and nitride (Cr3C2 CrN) fabricated using SLRS from a model system Cr Cr2O3 precursor materials. Varied particle sizes (<5–45 µm) simultaneously chemically-converted bonded into during selective processing in 100 vol% CH4 or NH3 gas. For each material, factors such as size, chemistry, optical properties, microstructure quantitative phase characterization microstructural imaging understand important aspects formation within an AM context. metal oxide systems produced yields up wt% total for nitrides reactive processing. However, when either was processed by itself, the simultaneous synthesis bonding approach resulted volumetric changes in-situ gas-solid conversion adversely affected layer microstructure. To circumvent internal stresses accompanied induced (which expands conversion) contracts), we demonstrate alternative method production near-net shape AM. By combining optimized ratios metal/metal precursors reactant gas, novel formulations undistorted, crack-free refractory sub-millimeter spatial resolution viable thickness powder bed fusion-AM. The results not only carbides AM-compatible but suggest transition may be compatible even though they cannot more traditional laser-assisted approaches.