Improvement of Rheological Characteristics of Carbon Containing Alumina-Rich Castable Matrix by Surface-Treated Graphite
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Vol. 61, No. 3, September, 2020
IMPROVEMENT OF RHEOLOGICAL CHARACTERISTICS OF CARBON CONTAINING ALUMINA-RICH CASTABLE MATRIX BY SURFACE-TREATED GRAPHITES R. Dutta,1 D. Pal Choudhury,1 S. Mukhopadhyay1,2 Translated from Novye Ogneupory, No. 6, pp. 37 – 40, June, 2020.
Original article submitted April 4, 2020. The main objective of this work was to explore the improved water dispersibility obtained in natural graphite after its surface treatment. The superior flowability of the aqueous suspension of an alumina-rich representative castable matrix incorporating that surface-modified graphite without prior sonication has been observed. The typical role of alumina-based thin coating on graphite has also been addressed. Keywords: alumina, castable, rheology, graphite.
acteristics of these two constituents. Their interactions in aqueous suspension in the presence of other microfines are also important in this connection. This paper highlights some interesting rheological features of surface-treated graphite in comparison with natural flaky graphite. The change in flow behavior of the representative alumina-rich castable matrices containing these two graphites has also been noticed.
INTRODUCTION The refractory materials utilized for continuous casting have gained increasing important throughout the last few decades. Alumina-carbon refractories have already been established for this purpose. Flaky graphite has long been recommended as a typical brand in this regard among other alternatives. However, the perception of graphite-containing refractory castable has not been satisfactorily validified due to the poor water wettability and inferior oxidation resistance of graphite. Scientists have attempted to bring about surface modification of natural graphite in several ways to achieve desirable flow property and better oxidation resistance of the alumina-carbon castable matrix [1 – 6]. An optimum flowability of matrix fines surrounding the refractory aggregates plays a vital role towards proper placement and homogeneity of the castable mix. Different kinds of additives and deflocculants have also been suggested by scientists for imparting adequate rheological characteristics to the unshaped refractories [7]. High alumna cement (HAC) is regarded to date as an effective refractory binder and an integral part of the monolithic matrix. Quite naturally the rheological properties of an alumina-rich castable matrix containing graphite and HAC are largely dependent upon the quantity and char1
2
EXPERIMENTAL A thin and selective coating of nanostructured Ca-doped g-Al2O3, derived by the sol gel route, has been developed over refractory grade natural graphite flakes. The surface treatment of the graphite and other procedural details have been described elsewhere [8 – 14]. The scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS) study of this coated graphite was performed using a JEOL JSM 5200 instrument. The rheological studies of coated and uncoated graphites have been conducted using the instrument DSR Broo
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