Indentation creep of window glass around glass transition

Depth sensing indentation is used here to investigate the viscous behaviour of a glass in a wide range of temperatures. A specific high temperature instrumented micro-indentation device was developed to perform creep indentation tests with several indenter geometries (spherical, flat punch and Vickers) up to 1100 °C with a maximum load of 15 N. The displacement vs. time curves are analysed by using a method based on a linear viscoelasticity assumption. Creep indentation tests are conducted on a standard window glass around glass transition between 540 and 640 °C. Results show no influence of load and indenter geometry on measurements in the permanent regime of creep. The temperature dependence of viscosity we found is in good agreement with those from the literature. The indentation creep method is therefore a very powerful way for studying the viscoelastic behaviour of materials. Compared to classical methods it has two main advantages: the easiness of samples preparation and the small volumes required.