Properties of Refractory Castables Tina Stendal Svendsen Product Manager 1
Refractory materials are subjected to following stress factors: Thermal - by high temperatures and thermal shock Mechanical - by pressure, impact, friction and airborne particles Chemical - by gases, liquids, build-up, slag and melts The properties of castables and their ability to withstand stresses are determined by: Raw materials Particle size distribution Chemical reaction between raw materials at various temperatures The properties of refractory castables can be analysed by a range of international test procedures 2
Bending strength; Modulus of rupture (EN ) Cold modulus of rupture Provides information on material structure (QC) Hot modulus of rupture Characterize the thermodynamic behaviour of the castable 3
Cold Crushing Strength (EN ) 4
Thermal Shock Resistance (EN ) Air quenching of 950°C hot specimens 5
Abrasion resistance (ASTM C 704) Temperature: 1000°C Abrasion media: SiC grains Testing angle: 45° and 90° Results: ≤ 5cm 3 loss: excellent 5cm 3 to 10cm 3 : very good 10cm 3 to 20cm 3 : good 6
Alkali resistance (CEN/TS 15418) Test media K 2 CO 3 or K 2 SO 4 7
Hot-melt slag and build-up 8
Slag resistance: Static test (CEN/TS 15418) 9
Hot melt slag resistance (dynamic test) 10
Open porosity (EN 933-1) Test pieces are saturated in water under vacuum 11
The influence of porosity on castable properties 12
Other tests Particle size distribution Thermal expansion / creep Chemical and structural analyses; SEM and XRD Thermal conductivity Refractoriness / refractoriness under load CO-resistance 13
Assessment of material data 14
15 Temperature Thermal property Application
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Summary Castables are subjected to thermal, mechanical and chemical stresses Wide range of international test standards to measure properties Some tests are targeted for quality control Other tests simulate operation conditions (temperature, chemicals) Test of corrosive slags can both static and dynamic Test slags at relevant temperatures There is a close relationship between porosity and the physical and chemical properties of castables When comparing datasheets: Be aware of test-temperature and of to which temperature has the test specimens been prefired prior to test 19