Abstract
Thermal shock is one of the most severe conditions to which a refractory lining can be subjected to during its industrial application. Thus, there are several methods available for testing thermal shock damage resistance of refractories. Among them, a very common method is the quench test, which consists of quenching a hot refractory bar into water. After that a retained mechanical property is determined. Considering this, the aim of the work herein is to compare the thermal shock damage resistance between two specimen sizes among several materials. The dimensions 150 mm × 25 mm × 25 mm and 160 mm × 40 mm × 40 mm were used. The small bars are generally used for mechanical characterization in the refractory field (recommended by ASTM C1171-05). The large bars, on the other hand, are a requirement of DIN 196-1, which regards procedures for testing cement materials. Experimental results have indicated that the thermal shock damage is bigger for the large bars, as predicted by theoretical aspects. Although the size difference between the specimens was not so big, it was possible to observe the size effect using a statistical treatment. Five different castable formulations, of which three contained eutectic aggregates, were tested. The highest variation found in thermal shock damage resistance because of the size was about 15%.
Highlights
The most interesting aspect of the investigation of specimen size effects on the thermal shock damage resistance of refractories is the better understanding of the variables related to the quench test
Before presenting the main discussion regarding this work, it is important to analyze the values of MOR and E of the bar-like specimens with different W-values
The retained-MOR indicated that the large specimens presented higher thermal shock damage than the small ones
Summary
The most interesting aspect of the investigation of specimen size effects on the thermal shock damage resistance of refractories is the better understanding of the variables related to the quench test. Literature[1,2,3] has provided solutions about this issue, it is sometimes neglected by refractory researchers and users Such aspect has been given emphasis in the work . It is well known that, during a thermal shock test, the larger the volume of a specimen, the higher the thermal gradient in it. This is because Biot modulus is directly proportional to the thickness. According to Cotterell et al.[1], mechanical size effects can influence the thermal shock damage resistance of specimens This issue was first pointed out in refractories by Kienow[2]
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