Preparation And Properties Of Porous Hydroxyapatite Ceramics Reinforced By Wollastonite

Bio-ceramics can compose part of human bones and teeth, partially or wholly repair or substitute certain organ and tissue or enhance their functions. The need for such bio-material and bio-ware is greater and greater owing to population aging and trauma increases resulted from industry, traffic and sports. Fortunately, with the development of material science and life sciences as well as tissue engineering technology, researchers find out step by step the reactions between bio-materials and human body, and in turn enable the traditional abiotic material to take part in life activity by constructing bio-structure and function. The research and development of bio-materials is of significance for economic and social prosperity.Hydroxyapatite (HAP), bearing similar ingredient and crystal structure with the main inorganic component of human hard tissue, demonstrates favorable bioactivity and bio-compatibility whose implantation incurs no stimulation or repellency and integrates strongly with the natural bones to offer frame for renascent of new bones. Hence it is the most prospective biomaterial in hard tissue trauma recovery and substitution field. Unfortunately, hydroxyapatite powder sold in the market has various crystal conformations and unfavorable sinter activity besides expensive cost. Further, owing to the typical brittleness of porous hydroxyapatite ceramic, its application is greatly limited. Therefore, it is very urgent and important to explore ways to optimize the precipitation synthesis process of hydroxyapatite powder and improve mechanical strengths of porous hydroxyapatite ceramics.In this paper, hydroxyapatite was precipitatedly synthesized and analyzed by means of phosphatomolybdic acid quinoline gravimetric method and EDTA capacity method respectively for Ca and P elements and further Ca/P ratio. Together with the X-ray powder diffraction (XRD), scanning electronic microscope (SEM), Infrared absorption spectrum (IR) analyses, the mechanisms of factors influencing the precipitation process of hydroxyapatite powder such as water-bath temperature, solution pH value, dosage of PEG20000 and initial reactant concentration were discussed respectively in order to optimize the synthesis process. On such a basis, the fine hydroxyapatite powders were prepared. And then the porous ceramics were sintered with synthesized hydroxyapatite and natural wollastonite powder as the stuff, starch as the pore-forming agent and polyvinyl alcohol as the bond. In turn XRD, SEM, IR, optical microscope and differential thermal analysis were employed to characterize the micro-structure...