J ‐Integral Measurements of the Fracture of 50% Alumina Refractories

The J ‐integral experimental technique was used to study fracture initiation in burned refractory bricks and refractory casta‐bles of the 50% alumina variety. In a comparison of J Ic and G Ic , and 2 y wof it is consistently observed that G Ic Ic <2ry Wof . The quantities ( J Ic ‐G Ic ) or ( J IC / G IC ), as well as ( 2y wof / G Ic ), can be applied to estimate the inelastic energy contribution to the crack‐tip process zone of these refractories. The latter two parameters distinctly classify the burned bricks and the casta‐bles into different fracture characteristics. As such, these parameters are potentially very useful in the microstruetural design of refractories.