Compaction pressure influence on the sintering of bioceramic materials

The use of ceramic materials varies and is determined by their properties and area of application. Orthopedics and traumatology have demand for porous materials for reconstruction of osseous defects. The material most closely fitting the natural bone in its structure and biological properties is hydroxyapatite HA (Ca₅(PO₄)₃OH) and triple-calcium phosphate (Ca₃(PO₄)₂) traditionally used to produce calcium-phosphate ceramics. High-temperature reactions lead to obtaining coarse-crystalline material with minimum porosity. Preparation of calcium-phosphate materials with large specific surface of the material contributes to the active bone formation compared to the dense calcium-phosphate ceramics. It was determined that compacting pressure and the packing index depends on the dispersion of materials. When compaction pressure is increased the open porosity of the material decreases by 10-15%. When sintering dense ceramics in the temperature range of 1100-1300°C the strength of the material samples increases to 130-160 MPa and open porosity decreases to 8-10%; total is 25-40% It characterizes an intensive sintering process in this temperature range. Introducing a pore-forming agent and sintering at 1250-1350°C showed that the strength improves with the increase of sintering temperature, while the open porosity ranges from 20-40% and the pore size corresponds to the size of the particles of a pore-forming agent. The results of the work allowed establishing the regularity of the influence of the quantity of pore-forming additives, sintering temperature, and the packaging index on the process of adjusting the size and number of pores for obtaining HA ceramics.