Colloidal forming of macroporous calcium pyrophosphate bioceramics in 3D-printed molds

A technique for colloidal forming of Ca2P2O7 macroporous bioceramics,based on low-pressure injection molding(LPIM)of a glycerol-water slip containing Ca2P2O7 and Ca(Н2PO4)2 into a plastic mold fabricated via FDM 3Dprinting,was proposed.Chemical reaction between the solid phases of the water containing slip-Ca2P2O7 and Ca(Н2PO4)2,resulting in brushite(CaHPO4·2H2O)formation,led to consolidation of the casting and preserved its complex architecture in the course of mold burning-out.Macroporous ceramics of Kelvin structure(70%macropores with the sizes from 2 up to 4 mm),based on a pre-defined composition with 10 wt%Ca(PO3)2 and sintered in liquid-phase regime,demonstrated a compressive strength of 1.4±0.1 MPa at a density of 22±2%.In vitro tests on bioactivity in SBF solution,as well as on resorption of the ceramics in model solution of citric acid,were carried out.