Thermal and mechanical cyclic tests and fracture mechanics parameters as indicators of thermal shock resistance – case study on silica refractories

Abstract

The paper discusses alternative methods to assess thermal shock in refractories. Thermal shock performance of two conventional silica bricks and two novice fused silica materials has been studied. Methods involving fracture mechanical tests of monotonic loading, repetitive thermal shock tests and cyclic strain controlled fatigue tests have been utilised. The amorphous fused silica is rather brittle. However low thermal expansion guarantees its superior thermal shock resistance. In-service crystallisation is to happen rather quickly. For crystallised fused silica of the studied morphology the tests coherently predict superior thermal shock resistance due to less brittle failure. Strain controlled fatigue test allows assessment of strain limits in the conditions of cyclic loading and thus combines the benefits of the thermal shock and monotonic fracture mechanics tests. Strain tolerance seems to be the property to correlate the results of the alternative test methods and those with the service loads.