Non-linear dissolution mechanisms of sodium calcium phosphate glasses as a function of pH in various aqueous media

Phosphate glasses for bioresorbable implants display dissolution rates that vary significantly with composition, however currently their mechanisms of are not well understood. Based on this systematic study we present new insights into these mechanisms. Two-stage was observed, time dependence initially parabolic and later linear, a two-stage model developed to describe behaviour. Dissolution accelerated by lower Ca concentration in the glass, pH medium. A mechanism is proposed, involving an initial stage where diffusion-controlled formation conversion layer occurs. Once stabilised, reactions become rate-limiting. Under transition sensitive nature solution conditions. These results reveal P$_{2}$O$_{5}$-CaO-Na$_{2}$O glass pH, provide insight mechanisms, particularly regarding between two stages.