Composite Ceramics Based on Pastes Including Tricalcium Phosphate and an Aqueous Solution of Sodium Silicate

Abstract

Preceramic samples were prepared from pastes based on the aqueous solution of sodium silicate and tricalcium phosphate with a given molar ratio of (Na2O · 2,87SiO2)aq/Ca3(PO4)2 = 1:3 after drying at 24 °C and then 60 °C for 24 h. It established the dependence of the plastic strength of these pastes on both time and temperature and the possibility of using them for extrusion 3D printing. The phase composition of ceramic was represented by unreacted β-TCP (β-Ca3(PO4)2) and β-rhenanite (β-NaCaPO4) after heat treatment at 500 °C. Further, an increase in temperature up to 700 °C led to the appearing phase of silicon dioxide (SiO2) and up to 900 °C, of sodium calcium phosphate (Na3Ca6(PO4)5). After heat-treatment at 1100 °C, ceramic samples consisted of the β-TCP (β-Ca3(PO4)2), sodium calcium phosphate (Na3Ca6(PO4)5), silicon dioxide (SiO2) and β-wollastonite (β-CaSiO3). The bending and compressive strength of the ceramics rose with increasing temperature from ≈6.8 MPa and ≈31.1 MPa at 500 °C to ≈10.6 MPa and ≈43.5 MPa at 1100 °C. The obtained composite ceramics consisted of biocompatible phases that are widely studied in the literature and may be used as a biomaterial for the treatment of bone tissue defects.