Feasibility of SiAlON-Si3N4 composite ceramic as a potential bone repairing material

In this study, SiAlON-Si3N4 composite ceramic are prepared by direct nitridation and investigated to overcome the limitations associated with ceramic Si3N4, which includes the difficulty in fabricating ceramic Si3N4 into shaped parts for use in the human body. Phase composition and microstructure of the SiAlON-Si3N4 composites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively, and the porosity, bulk density, compressive strength, and ion release were also measured. The biological properties were evaluated by bone cell cultures on the ceramic surfaces. Results show that SiAlON-Si3N4 is formed by the reaction of Al, Si, and Al2O3 with nitrogen at high temperature that forms Si3N4, thereby fabricating SiAlON-Si3N4 composite ceramics. Some alpha-Si3N4 grains underwent a phase transition from alpha-to beta-Si3N4 fiber at high temperature. Porosity of the samples increases with increasing Si3N4 content, while the bulk density of the samples decreases. The compressive strength increases and then slightly decreases with increasing Si3N4 content. Water leaching experiments of the SiAlON-Si3N4 composite ceramics reveal that the composites exhibit outstanding chemical stability. Studies using bone cell culture indicate that the cells present a fusiform and extend two or three thin pseudopodia. The phenomena demonstrate that MC3T3-E1 cells have excellent growth activity and have the potential ability to proliferate to osteocytes on the surfaces of the samples, thus suggesting that SiAlON-Si3N4 based ceramics are biocompatible and could be implemented as a potential bone-repairing material.