Formación de hidroxiapatita, Ca5(PO4)3∙OH, en presencia de silicatos

Abstract

Hydroxyapatite Ca₅(PO₄)₃OH (HAp) is a crystalline phase which has several applications within the domain of special cements. This phase takes an important role in the cement reactions for the reconstruction of skeletal functions (medical domain). It is used also to improve properties of dental material. On the other hand, it is investigated to develop chemically bonded ceramics. In this paper we study the formation of HAp with β-C₂S and C₅PS, using some compositions in the rich lime portion of the system CaO-SiO₂-P₂O₅-H₂O (at atmospheric pressure and open system). These compositions lie in the range of: CaO: 67-71 %; SiO₂: 3-18%; P₂O₅: 9-29% (Wt%). The preparations are made using solid state reactions, with thermal treatment at open system. The identification of phases was carried out using X-ray diffraction, Infra-Red absorption and Differential Thermal Analysis. We delimit a spectroscopy little domain lies in the range of CaO-69,5-70%; P₂O₅-16,2-19,5%; SiO₂-11,1-13,6%. Within this domain, the crystalline phases solid state compatibility at temperature near 1000ºC are HAp, β-C₂S, C₅PS.