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

Ya Yu Filippov; E D Orlov; E S Klimashina; P V Evdokimov; T V Safronova; V I Putlayev; J V Rau

doi:10.1016/j.bioactmat.2020.02.013

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

Bioact Mater. 2020 Mar 6;5(2):309-317. doi: 10.1016/j.bioactmat.2020.02.013. eCollection 2020 Jun.

Authors

Ya Yu Filippov^{1

2}, E D Orlov¹, E S Klimashina^{1

3}, P V Evdokimov^{1

3}, T V Safronova^{1

3}, V I Putlayev^{1

3}, J V Rau⁴

Affiliations

¹ Department of Materials Science, Lomonosov Moscow State University, Moscow, Russia.
² Institute of Mechanics Research, Lomonosov Moscow State University, Moscow, Russia.
³ Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia.
⁴ Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche (ISM-CNR), Via del Fosso del Cavaliere 100, 00133, Rome, Italy.

Abstract

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 3D-printing, 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.

Keywords: 3D-printing; Bioceramics; Calcium metaphosphate; Calcium pyrophosphate; Colloidal forming; Kelvin structure.