Studies On AW Bioactive Glass-Ceramic Prepared By Sol-Gel Method

Apatite/Wollastonite bioactive glass-ceramic(AW GC) is a type of biomaterials with excellent mechanic properties, bioactivity and biocompatibility. For a long time, AW GC has played an important role for improving the health level of human being as a bone repairing and replacement material. Traditionally, AW GC is prepared by the following steps: 1. prepare the parent glass through melt method in a high temperature; 2. Crystallize in the parent glass through proper heat-treatment. This paper pioneered to prepare the predecessor powder of AW GC through sol-gel method, and consequently prepared AW GC and its porous materials.To prepare the predecessor powder of AW GC, the composition was accorded with MgO4.6, CaO44.9, SiO234.2, P2O516.3 and CaF20.5 (wt% ). By screening test, tetraethoxysilane(TEOS), triethylphosphate(TEP), calcium nitrate tetra-hydrate, magnesium nitrate hexa- hydrate and ammonium bifluoride were adopted as the raw materials. They were added in the above listed order. As the result, the uniform, lucid and stable sol was obtained. It was also proved that: 1. the proper temperature improving was favored for gelling, and the suitable temperature was 50-60 ; 2. PH value had some influence on gelling, and gel formation was more rapid when PH value was 5-6. The aging temperature was 60 ( for 50h), and the drying temperature was 180 (for 48h). After the dry gel was calcined in 500-550 , sieved with the griddle of 325 mesh, we obtained the predecessor inorganic powder with good distribution of particle size, gooddispersibility, high reactivity and noncrystalline structure.The powder was molded through pressure molding method with 10~20wt% 3~4wt% PVA aqueous solution being added. Dense samples were compressed in lOMPa, and porous samples were compressed in 5MPa. The best sintered temperature was 1250 , keeping 3 hour. The XRD pattern showed the diffraction peaks of apatite phase and wollastonite phase, which were expected. FTIR spectra also showed the corresponded structure. SEM analyzing proved the microporous structure of the material. Compressive strength of the material reached 45 MPa, which was satisfied to be some bone-repairing biomaterials.To get the materials with macroporous structure, the predecessor powder was sintered, and pore-created, and calcined to get rid of the poreforming material. The poreforming material was the particles of stearic acid of 20-30 mesh. About 30~40wt% of them were added to get the porous materials with 45-55% porosity. The materials had both micro pores and macro pores, which connected together. The size of micro pores was 1 m, and the macro pores was 400 m. The size and the structure feature of the materials would be favor for the incoming of blood vessel and bone tissue. Elementary study proved that much grain of apatite could form in the surface of the materials, and might become apatite layer, which endowed the material with bioactivity.Elementarily studied the preparation process of AW GC / - TCP composite material. Elementarily investigated the preparation of Rat marrow stromal cells(MSC)/AW GC composite and Rat periosteum osteoblast/ AW GC composite. These composites were expected to have bright application potential in bone tissue engineering.