A STUDY BY DENSITY-MEASUREMENTS AND INDENTATION TESTS OF A CALCIUM SILICOPHOSPHATE BIOACTIVE GLASS WITH DIFFERENT MGO OR SRO CONTENTS

Vickers and Knoop indentation techniques and density measurements have been employed to study the structure of two series of glasses in the system CaO-RO-SiO2-P2O5-CaF2 (R = Sr, Ca, Mg) with: (a) constant alkal ine earth oxide content, but using different cations (Ca, Ca + Sr, Ca + Mg), and (b) increasing alkaline earth concentration (Mg and/or Ca). Samples have been prepared by melting the raw materials at 1400 degre es C, and pouring the liquid on a steel plate. From the experimental d ata, microhardness, H-V, fracture toughness, K-IC, and values for mean atomic volume, V-A, and ionic volume fraction, V-F, were obtained. Th e last parameter is proposed as a suitable one for the analysis of var iations in cationic coordination numbers, n. The results show that Mg, Ca and Sr have similar values of n. The value of n is proposed to be six.