Tricalcium phosphate (TCP) ceramic scaffolds were made by the fused filament fabrication (FFF) using different grades of Ethylene Vinyl Acetate (EVA) as a thermoplastic binder. Stearic acid was studied as a processing aid. A wide range of rheological properties, shaping and debinding behavior could be observed with feedstocks made with different EVA grades. The addition of stearic acid affects flexibility of the solid filaments, the viscosity of feedstocks, and causes a pronounced yield stress behavior. These effects are strongly dependent on the molecular weight of the EVA and influence the printing process and shape stability during the debinding process. EVA binder system works well for thin and small parts, made with nozzle sizes below 0.4 mm, whereas samples made by thicker nozzle size form defects during debinding process. TCP scaffold structures with fin struts of 0.27 mm and partition wall thickness of 0.25 mm and a layer thickness of 0.20 mm could be successfully shaped, debinded and sintered. Excellent fusion between the different layers was achieved, since no defects at the interface could be detected.
Due to the inhibiting behavior of Cu, NiCu alloys represent an interesting candidate in carburizing atmospheres. However, manufacturing by conventional casting is limited. It is important to know whether the corrosion behavior of conventionally and additively manufactured parts differ. Samples of binary NiCu alloys and Monel Alloy 400 were generated by laser powder bed fusion (LPBF) and exposed to a carburizing atmosphere (20 vol% CO–20% H2–1% H2O–8% CO2–51% Ar) at 620 °C and 18 bar for 960 h. Powders and printed samples were investigated using several analytic techniques such as EPMA, SEM, and roughness measurement. Grinding of the material after building (P1200 grit surface finish) generally reduced the metal dusting attack. Comparing the different compositions, a much lower attack was found in the case of the binary model alloys, whereas the technical Monel Alloy 400 showed a four orders of magnitude higher mass loss during exposure despite its Cu content of more than 30 wt%.
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