Refractoriness points to temperature at which the material softens. Refract oriness under load (RUL) is a measure of the deformation behavior of refrac tory ceramic products subjected to a constant load and increasing temperatu re.
RUL is a critical property for refractory bricks, which basically reflects the service temperature of the bricks, raw materials, etc. The RUL is of gr eat importance to check the suitability of refractory products for high-tem perature applications. It gives an indication of the temperature at which t he bricks will collapse, in service conditions with similar load. The refra ctoriness is indicated by PCE (Pyrometric cone equivalent). It should be hi gher than the application temperatures.
Refractoriness decreases when refractory is under load. Refractoriness unde r load is an important consideration because usually a refractory fails at a lower temperature when subjectured to load. Therefore more important is r efractoriness under load (RUL) rather than refractoriness.
The refractoriness under load test (RUL test) gives an indication of the te mperature at which the bricks will collapse, in service conditions with sim ilar load. However, under actual service where the bricks are heated only o n one face, most of the load is carried by the relatively cooler rigid port ion of the bricks. Hence the RUL, test gives only an index of the refractor y quality, rather than a figure which can be used in a refractory design. U nder service conditions, where the refractory used is heating from all side s such as checkers, partition walls, etc. the RUL test data is quite signif icant.
It is generally measured as the softening temperature. It is necessary that a refractory material should have a softening temperature higher than the operating temperature of the furnace in which it is to be used. Most of the commercial refractories do not exhibit sharp melting points and they softe n gradually over a range of temperatures. The temperature range in which th e softening of refractory products occurs is not identical with the melting range of the pure raw material; therefore it must be reliably determined.
RUL values(T0.6 @0.2MPa) for fireclay-based refractory bricks are usually b
es could vary depending different industrial standards,different companies in different areas.
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