Mechanical And Biocompatible Properties Of Graphene/Hydroxyapatite Ceramic Composites By Microwave Sintering

Hydroxyapatite(HA), contained essential calcium and phosphorus elements for human bone tissue, is the principal inorganic composition in bones and teeth of human. Due to its high biocompatibility, bioaffinity and osteoconduction, HA can be used as a potential biological ceramic material. However, the intrinsic brittle, low strength and poor toughness of HA greatly affect its application in biomedical. In order to meet the mechanical requirements of implants, the toughening of HA is normally improved by adding the second phase material. As an advanced material with high mechanical, graphene(r GO) is widely used to improve the toughness of ceramic materials.In this paper, a new hydroxyapatite toughened by grapheme was synthesized to solve the above issue. The graphene/hydroxyapatite(r GO/HA) powders were fabricated by co-precipitation method, and the ceramic was prepared by microwave sintering. The characterizations of the r GO/HA powders and ceramics were analyzed, including microstructure, phase and surface morphology. The effects of the process parameters, such as sintering temperature, holding time and graphene content, on the mechanical properties of the composites were studied. The in-vitro biocompatibility of r GO/HA composites was evaluated through apatite-forming ability, osteoblast adhesion and proliferation test.The results showed that the best prepared parameters of the r GO/HA powders were the initial reactant concentration of 0.3mol/L, the calcination temperature at 800? and the content of 3wt.% PEG2000. The formed r GO/HA powders had good dispersity and uniform particle size. As increase the temperature and holding time of microwave sintering, the fracture toughness, relative density, microhardness, and compressive strength of both HA materials and r GO/HA composites increased firstly and then decreased. The best mechanical performance of r GO/HA was obtained at 1100 ? for 30 min. The microhardness, fracture toughness and compressive strength of r GO/HA composites firstly increased then decreased with increasing the content of graphene. When the graphene increased to 0.30 wt.%, the microhardness, fracture toughness and compressive strength reached the best, which were 6.06 GPa, 1.4702 MPa·m1/2 and 119.222 MPa. Compared to pure hydroxyapatite, the microhardness, fracture toughness and compressive strength of r GO/HA increased by 11%, 49% and 82%.The apatite-forming rate of HA-0.3wt.%r GO was faster than HA. Osteoblast adhered to the surface of HA-0.3wt.%r GO was almost similar with that of HA. With the increasing of incubation time, the proliferation rate of both HA and HA-0.3wt.%r GO exhibited the overall upward trend. At the same time of node, the proliferation rate of HA-0.3wt.%r GO was slightly lower than that of HA.