ИСТИНА

The work tackles the issue of bioceramics with interconnected macropores with special architecture of pores space. Kelvin structure and gyroid, as a member of triply-periodic minimal surfaces family, were chosen to reach desirable permeability (up to 1000 Darcy) in order to reveal osteoconductivity. FEM-analysis of loading and simulation of fluid flow through the structure (SolidWorks 2013) facilitated making a choice. The above complex shapes were reproduced as phosphate ceramics scaffolds via DLP-stereolithography of light-curable slurries based on Ca3(PO4)2 and Са3-хМ2х(РО4)2 (x = 0 – 1, M = Na, K) ceramic powders. Optimization of the process parameters as well as reaching high lateral resolution of printing (up to 30 μm) were underlined with the study of photosensitivity of the slurries and light scattering in them. To convert the as-printed scaffolds into the ceramics one, preserving their geometry, a special regime of thermal treatment allowing release of polymer with the rate lower than 0.1 wt.%/min was elaborated. Time-temperature profile of the regime was stated through the inspection of kinetics of polymer pyrolysis. Detailed study of densification and grain growth in the course of sintering of ceramic scaffolds made us possible to fabricate prototypes of bone implants (for small laboratory animals, cylinders with o.d. = 2–3 mm and height up to 6 mm) with overall porosity up to 80%, demonstrating compressive strength up to 12 MPa and fracture toughness up to 0.7 MPa·m1/2.