Electrocast A1203-ZrO2-SiO2 refractory blocks are used extensively to line the glass contact areas of tanks for commercial production of float and container glass. A major corrosive wear mechanism in these tanks is bottom drilling whereby a dense metallic droplet bores its way through the bottom of the tank leading to potentially disastrous loss of the contents. This problem has been exacerbated by the trend to extensive recycling of crushed glass cullet which is contaminated with metal from bottle wrappers, labels or tin from the float glass process. We report here a detailed examination of the microstructure around a penetrating metal droplet removed from a glass tank liner which had been in place for 12 years, which illustrates the corrosion mechanism.
