Success Story

Materials Characterisation for Refractory Materials

Refractory materials are ceramic materials that are designed for service temperatures of around 1,500°C and are mainly used in furnace linings for the iron, steel, glass, aluminium and cement industries. More than 10 million tons of refractory materials are produced annually worldwide. These materials are subjected to severe thermomechanical loading due to rapid changes in temperature. Specific material parameters can be used to assess and describe the material’s thermal fatigue resistance.

A New Method for Measuring Shear Strength at High Temperatures

Shear strength at high temperatures is an important parameter to be taken into account in the design of refractory linings. Shear strength is usually measured using a triaxial test, which is however not suitable for high temperatures. As the new method allows shear strength to be measured at temperatures up to 1.500° C, this parameter can be used in finite element simulations and the prediction of material behaviour in industrial high-temperature applications.

High-temperature processes, e.g. in steel production, cause various stresses and shear loads in refractory linings and may eventually lead to material failure. Shear strength is usually measured using the triaxial test, in which a testing machine and a hydraulic fluid apply pressure on all sides of a cylindrical specimen. The use of a liquid makes this method unsuitable for high temperatures. The aim of the project was thus to develop a new method for measuring shear strength at temperatures up to 1,500° C.

The new approach involves loading two prisms notched at different angles with increasing force until shear occurs along the notch. The specimens are loaded uniaxially, which means that the test can be carried out in conventional testing furnaces. In parallel, a finite element model is used to determine the shear stress for the two prisms. The two results can then be used to calculate the shear strength. The results allow refractory materials to be classified according to shear strength at service temperature and can also be used as input for finite element simulations of refractory linings. The method provides important economic benefits by reducing the consumption of refractory materials and consequently cutting CO2 emissions in the manufacturing process of refractory building materials.

The project was carried out in close cooperation with RHI AG (Leoben), Pyrotek Inc. (Montreal), voestalpine Stahl Linz GmbH (Linz), GEMH Limoges (Limoges) and the Chair for Ceramics of the University of Leoben.