The results of an integrated study of external factors on wear resistance of periclase-chromite refractories in vacuum chamber lining are discussed. It is established that the mineral composition and structure of magnesian-spinellide refractories are the least liable to transformations.The existing technology of melting transport metal at the Nizhnii Tagil Metallurgical Works includes treatment of steel in a circulation vacuum chamber intended for degassing and refining steel. Reliable performance of the vacuum chamber, which depends on the state of its lining, is essential to implement a steady degassing procedure. The lining of a vacuum chamber consists of three layers: the heat-insulating (calcium silicate plates), reinforcing (lightweight, high-grade, fireclay brick), and working layer (periclase-chromite brick based on a melted or sintered material). The most expensive is the working lining, especially in the lower part of the vacuum chamber and in the branch pipes. Therefore, the development of high-quality resistant refractories for steel degassing is an important and promising line of research.To determine the most significant factors affecting the wearing rate of refractories, we used the service parameters of forty complete campaigns of vacuum chambers lined with refractories produced by the same company. In processing these service parameters, we analyzed the dependence of the specific wear of refractories on 11 factors and then selected the most significant ones using the pairwise correlation method: average degassing duration; residual pressure in the chamber during metal degassing; the number of gun-concreting operations; the average consumption of gunite per operation. After data processing, the latter factor was excluded from analysis as being non-significant. Then we calculated a multiple regression with correlation coefficient 0.67 characterizing the degrees of the mutual impact of the considered parameters. The regression equation has the following form:where X 1 is the average degassing duration, X 2 is the residual pressure (<300 Pa) in the chamber during steel degassing; X 3 is the number of gun-concreting operations.The equation reflects the influence of the service conditions on specific wear and does not include an estimate of the product quality. Therefore, we compared the resistance and specific wear of three types of experimental refractory samples (Nos. 1, 2, and 3) that differed in their qualitative parameters. The results are shown in Tables 1 and 2. The data in Tables 1 and 2 show that the specific wear of refractories in the discharge pipe depends not so much on the qualitative parameters but to a great extent on the quality of products in the inlet branch pipe. It is here that refractories experience the most stringent service conditions: additional cooling of the product surface by a neutral gas between the heats and perceptible turbulence of metal, which causes additional erosion of the products. These reasons are largely responsible for the increased wear of refractories in th...
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