Preparation of porous 45S5 bioactive glass by gas foaming

Bioactive 45S5 glass is a silicate-base material used for the regeneration of hard tissues such as bones and middle ear bone. Up to day، several efforts have been made to provide macro-porosity in the glass structure. The porosity plays an important role in healing process by increasing the rate of tissue reconstruction as well as biodegradation. In this work، macro porosity was introduced into the glass structure via gas foaming technique as a simple and effective method. The glass was produced by melting method، ground to fine powder and mixed with various amount of calcium carbonate as gas-foaming agent. The mixture was pressed in tabular shapes and heat treated at 1150°C. CO2 gas produced from thermal decomposition of CaCO3 passed through the soften glass specimen led to formation of spherical macro-pores. The size and content of the pores depended on the amount of calcium carbonate. In this work، a macro-porous glass specimen with 60% porosity and macro-pore size of 60 μm was achieved using 1. 8% wt of calcium carbonate. The results showed that the Heat treating caused to glass crystallization without any undesirable effect on its bioactivity.