SURFACE PHENOMENA IN GEL-DERIVED GLASSES AND GLASS-CERAMICS MATERIALSOF THE CAO-P2O5-SIO2 SYSTEM

Three types of glass-ceramics materials of the CaO-P2O5-SiO2 system we re obtained using the sol-gel method and applying calcium nitrate, tet raethyl orthosilicate, and triethyl phosphate as precursors of the res pective oxides. The base materials were also modified with the additio n of 5 mole % Al2O3, using aluminium tri-sec-butoxide as its precursor . Gels were heated up to the temperature 700 degrees C. It has been fo und that after heating these materials contain a glassy phase, hydroxy apatite and wollastonite; there were important differences in the phas e compositions as well as in the pore structure of these materials. Ma terials after treatment were put into simulated body fluid. After a di fferent time periods the surface changes of these materials were exami ned using FTIR, SEM, and EDAX methods. It has been found that the bone -like hydroxyapatite is formed on the surface of gel-derived materials and the time necessary to forming the continual layer of this compoun d is dependent upon the chemical composition of the base materials. On I;he basis of conducted examinations the attempt of the explanation o f the hydroxyapatite formation mechanism was undertaken, The results o f our experiments can be interpreted as indicating the bioactivity of obtained gel-derived materials. This means that these materials used a s bone implants can be permanently joined to the bone.