NONTRADITIONAL METHODS FOR OBTAINING GLASSES FOR COATINGS - A RAMAN AND INFRARED VIBRATIONAL STUDY

Synthetic methods which provide alternatives to the oxide melting meth od for the preparation of inorganic glasses are described. These metho ds were monitored by Raman spectroscopy. The transformation products i nvolved in two main synthetic methods, the 'sol-gel' method illustrate d here for obtaining glassy SiO2 and the 'polymeric' route used for th e first time in the preparation of calcium phosphate glasses (CaO.P2O5 , calcium metaphosphate; xCaO. P2O5, calcium oligophosphates, where x less-than-or-equal-to 1.6) are characterized and discussed using their Raman spectra. These alternative methods allow vitreous materials to be prepared at moderate temperatures. They can therefore be important in the field of biomaterials for coating metal implants with bioactive glasses and ceramics. The melting method (for glasses) and the plasma spray technique (for ceramics) frequently induce changes of stoichiom etry in the coating and also activation of the support material, metal or alloy, resulting in a lack of biocompatibility.