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.