Three-Dimensional-Printed Molds from Water-Soluble Sulfate Ceramics for Biocomposite Formation through Low-Pressure Injection Molding.

Powder mixtures of MgSO 4 with 5-20 mol.% Na 2 SO 4 or K 2 SO 4 were used as precursors for making water-soluble ceramic molds to create thermoplastic polymer/calcium phosphate composites by low pressure injection molding. To increase the strength of the ceramic molds, 5 wt.% of tetragonal ZrO 2 (Y 2 O 3 -stabilized) was added to the precursor powders. A uniform distribution of ZrO 2 particles was obtained. The average grain size for Na-containing ceramics ranged from 3.5 ± 0.8 µm for MgSO 4 /Na 2 SO 4 = 91/9% to 4.8 ± 1.1 µm for MgSO 4 /Na 2 SO 4 = 83/17%. For K-containing ceramics, the values were 3.5 ± 0.8 µm for all of the samples. The addition of ZrO 2 made a significant contribution to the strength of ceramics: for the MgSO 4 /Na 2 SO 4 = 83/17% sample, the compressive strength increased by 49% (up to 6.7 ± 1.3 MPa), and for the stronger MgSO 4 /K 2 SO 4 = 83/17% by 39% (up to 8.4 ± 0.6 MPa). The average dissolution time of the ceramic molds in water did not exceed 25 min.