Gradient ceramic structures via multi-material direct ink writing

• Published in: Applied materials today Vol. 40; p. 102366
• Main Authors: Pelz, Joshua, Ku, Nicholas, Shoulders, Taylor, Guziewski, Matthew, Figueroa, Samuel, Swab, Jeffrey J., Vargas-Gonzalez, Lionel R., Meyers, Marc A.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2024
• Subjects: Direct ink writing; Dynamic mechanical analysis; Failure/fracture mechanisms; Functionally graded material (FGM), Layered structures; Not in keyword index: additive manufacturing; Robocasting, etc.; Structure-property relationship; Functionally graded material (FGM), Layered structures; Not in keyword index: additive manufacturing; Failure/fracture mechanisms; Structure-property relationship; Direct ink writing; Robocasting, etc.; Dynamic mechanical analysis
• ISSN: 2352-9407
• DOI: 10.1016/j.apmt.2024.102366

•Dense boron carbide-silicon carbide composite ceramics with composition tailored at the mesoscale were produced by direct ink write additive manufacturing followed by sintering.•Two configurations were generated: compositional layer-to-layer steps, and homogeneous composition throughout.•Mechanical tests were performed in cube and dumbbell geometries. Dumbbell geometry compression specimens have a compressive strength that is 68 % (quasistatic) and 86 % (dynamic) higher than that of cube geometry and show a greater strain rate dependence.•The rate dependency is attributed to the competition between crack propagation and loading velocities. As the loading velocity increases, the nucleated cracks have greater difficulty in coalescing and the strength increases.•These composite ceramics present a bright potential for armor applications. Dense boron carbide-silicon carbide specimens with composition tailored at the mesoscale were produced by direct ink write additive manufacturing in three configurations: I, 2 % and II, 10 % compositional layer-to-layer steps, and III, homogeneous composition throughout. Flexural strength, indicative of tensile failure, is the highest for the Type-II design (366 MPa) due to its compressive residual stress state in the surface layers. Analysis of thermally-induced residual stresses predicts the ranking of the flexural strengths obtained for Type-II (highest), Type-I (intermediate), and Type-III (lowest) specimens. Compressive strength is load-orientation independent, highly strain-rate dependent, and reduced for specimens with thermal residual stress. Mechanical tests were performed in cube and dumbbell geometries. Dumbbell geometry compression specimens have a compressive strength that is 68 % (quasistatic) and 86 % (dynamic) higher than that of cube geometry and show a greater strain rate dependence. The rate dependency is attributed to the competition between crack propagation and loading velocities. Type-I dumbbells show the highest mean compressive strength of 3.96 GPa (quasi-static) and 5.11 GPa (dynamic). The failure mode evolves from mixed intergranular/transgranular at low strain rates to transgranular at high strain rates. High-speed video analysis indicates that dumbbell geometry specimens fail in compression due to microcrack growth and coalescence, while cubes fail due to the axial macrocracks that develop at the specimen/load platen interface and propagate into the specimen parallel to the loading direction (end splitting). This work demonstrates the impact of compositional variation, tailored by additive manufacturing, on the mechanical performance of ceramic composites. [Display omitted]