3D printing of high-strength water-soluble salt cores via material extrusion

Core materials with high strength and excellent collapsibility are important for the manufacture of hollow composite structure castings. In this work, a novel technology to fabricate water-soluble Na2SO4-NaCl-based salt cores with high strength and low cost by material extrusion (ME) was reported. The water-soluble Na2SO4 and NaCl powders were used as the matrix materials, and the bauxite powder was used as the reinforcing material. The effects of bauxite powder content and liquid phase sintering parameters on the properties of the salt cores were studied. The results show that the salt-based slurry exhibits shear thinning property within the studied bauxite powder contents. When the content of bauxite powder was 20 wt.% and the sintering was at 630 ℃/30 min, the obtained salt cores show an optimal comprehensive performance, with the bending strength, linear shrinkage, water solubility rate, and moisture rate of 24.43 MPa, 6.3%, 207.6 (g/min·m2), and 0.29%, respectively. The complex water-soluble salt core samples prepared under optimal parameters display high-strength and well-shaped morphology.