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

Abstract

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 Na 2 SO 4 -NaCl-based salt cores with high strength and low cost by material extrusion (ME) was reported. The water-soluble Na 2 SO 4 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•m 2 ), and 0.29%, respectively. The complex water-soluble salt core samples prepared under optimal parameters display high-strength and well-shaped morphology.

Advances in Metal Casting Technology: A Review of State of the Art, Challenges and Trends—Part II: Technologies New and Revived

“…This study is of particular interest, as it relies on extrusion-based additive manufacturing for shape generation, suggesting a path to highly complex core geometries. Mechanical properties are further enhanced via a liquid phase sintering step at 630 • C, resulting in up to 24.43 MPa of bending strength [159]. An further extension of these investigations was recently published by Gong et al in which strength levels of 59.08 MPa are reported for codundum powder reinforced salt cores with an matrix composed of Na 2 SO 4 and NaCl [179].…”

“…Beyond 3D sand printing, further AM techniques have gained importance in the production of lost cores. A very special example is the extrusion-based AM of Na 2 SO 4 -NaCl salt cores, as proposed by Gong et al Depending on the composition, which may include bauxite powders as reinforcing additive, their materials achieved room-temperature bending strength levels of up to 24.43 MPa, exceeding the salt cores evaluated by Fuchs et al in HPDC by one third [173] and, thus, possibly paving the way for the introduction of 3D-printed lost cores to this demanding process [159].…”