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The Influence of Titania, Carbon Black and Graphite on the Spinel Formation in a Magnesia Alumina Castable
J. Angelkort, L. Himmel, Y. Lakotta-Weinhold, A. Reichert, M. Mix
Intocast AG, Westpreussenstrasse 30, 47809 Krefeld, Germany
received September 7, 2024, received in revised form February 27, 2025, accepted April 30, 2025
Vol. 16, No. 3, Pages 135-140 DOI: 10.4416/JCST2024-00017
Abstract
In this work, we studied the effect of small additions of titania and three carbon sources on the spinelization of magnesia alumina castables. Compared to additive-free reference samples, titania-containing magnesia alumina castables were found to exhibit improved sinterability and higher cold crushing strength after firing. In parallel, significantly higher amounts of spinel formed during heat treatment when titania had been added to the castable.
For the carbon-containing samples, the grain size of the carbon source proved to be an important parameter controlling the influence on spinelization. While the addition of carbon black (particle size d90 < 1 µm) clearly facilitated the spinel formation at a temperature of 1 200 °C, the influence of small-flake graphite (particle size d90 ∼ 75 µm) was less pronounced. The use of large-flake graphite (particle size d90 ∼ 180 µm) ultimately even hampered the spinelization reaction at this temperature. This latter effect is attributed to the presence of large graphite flakes which presumably inhibit the chemical reaction in the sample by blocking the direct contact between alumina and magnesia grains.
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Keywords
Spinel formation, castable, titania addition, carbon addition, sintering.
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