Stress Corrosion Cracking of Bioglass^TM

Abstract

The objective of this study was to investigate the stress corrosion behaviour of BioglassTM 4555 in order to predict the lifetime of the glass in use as a load-bearing prosthetic device. As part of this study, the development of BioglassTM and the medical tests conducted to assess the glass's biocompatibility are reviewed. The results of implant tests in laboratory animals which indicate that stress corrosion cracking of the glass may be a prohibitive factor to its use are presented. The theories of glass corrosion and stress corrosion cracking of silica based glasses are discussed and an extensive review of the literature presented. The corrosion behaviour of the glass was analysed and found to be similar to that obtained by previous workers. The depths of the corrosion layers were found to be smaller. This was attributed to alumina contamination of the glass. The fatigue parameters of the glass were measured by slow crack-growth studies and strength measurements in a corrosive solution simulating the physiological environment. The values of A and n in the equation relating crack velocity (v) and stress intensity (K1) v=AK1n, were found to be 1x10-173 and 30 respectively. Lifetime predictions for the glass were performed. It was determined that the glass was suitable for use as a prosthetic device if the maximum tensile stress encountered in vivo did not exceed 15MPa.