The kinetics of corrosion of e-glass fibres in sulphuric acid

The corrosion of glass fibres in acid solution is well known and is thought to be responsible for many instances of failure in glass reinforced plastic materials. It is generally accepted that cations are leached from the glass matrix into the acid solution, but the precise chemical mechanism is still not fully understood. Anions that form insoluble salts or complexes with cations in the glass can increase the rate of leaching and accelerate the corrosion process. In the case of sulphuric acid, it is suggested that sulphate anions form precipitates with calcium ions leached from the glass and this in part increases the rate of corrosion. This paper investigates the corrosion rate of glass fibres exposed to sulphuric acid at different concentrations and temperatures, by measuring the residual strength of the fibres before and after exposure. The rate of leaching of cations into solution is also measured using atomic absorption spectroscopy and ICP-MS. Increase in temperature increases the rate of corrosion and this can be modelled using a simple Arrhenius plot to determine the activation energy of the process. Strength retention and leaching rates of individual cations are compared in an attempt to explain the mechanism of corrosion.