Refractory castables composition

Other common refractory forms include setter tile and kiln furniture, fusion-cast shapes, cast and hand-molded refractories, insulating refractories. castables and gunning mixes, plastic refractories and ramming mixes, mortars, composite refractories, and refractory coatings,... 

As mentioned, refractory castables are combinations of refractory aggregates, matrix components, bonding agents, and admixtures. The proportions of each component used vary in each castable composition to achieve the desired physical and chemical properties and characteristics for the intended castable application. The general range of component quantities in a refractory castable is shown in Table 2. 

However, it should be pointed out that the composition of the refractory castable matrix is of special significance, too. The chemical reactions between the main refractory matrix components like Si02, CaO, and AI2O3 with the oxides, resulting from the steel oxidation, like Ct203, NiO, Fe304, and FeO should be taken into consideration. 

The variables of the repulsive term [Ur in Eq. (5)] that exert a major effect on the profile of the Ut curve are the Stem potential and the Debye parameter K, since the other parameters are usually constant for a given castable composition. To control the dispersion state of particles in refractory castables, it is therefore essential to understand the factors that determine the Stern potential and the Debye parameter. 

Current issues on refractory monolithics include no-cement castables, self-flow and free-flow mixes [64], and special compositions such as spinel-based [65], placement techniques [66], new applications (i.e., crown superstructures for glass melters [67]), characterization [68, 69], and basic castables [70, 71]. Specialized publications have compiled and reproduced most of the most important topics [i.e, 72-74], which include the following ... 

Test certificates for refractory bricks, cements, and castable lining material (their properties and compositions) shall be obtained. Some typical values are given below. Plant engineers may specify more stringent conditions to suit the operating requirements. 

A special type of this material is called SIFCA slurry infiltrated fiber-reinforced castable. This is a composite material of ceramic matrix with calcium aluminate cement and with aggregate made of aluminum oxide, mullite, zircon and calcined fireclay. The matrix is reinforced with stainless-steel fibres. SIFCA is used to made pre-cast elements for refractory structures, where temperature can rise up to 1100°C. Heat curing is often used during the pre-casting. Another kind of similar material is called SIMCON slurry infiltrated mat concrete in which arrays of single fibres are replaced by a system of steel mats for better and easier distribution of reinforcement (Murakami and Zeng 1998). 

Sometimes misunderstandings occur between the bricklayers and the producers of SiC-based castables. In the language of refractory producers, a castable that should be installed in the cavity of a steel shell is called a troweling mix, but bricklayers at smelters continue to call it a ramming mix. This latter term is more likely for the composition that is filled in between the deck plate and the upper part of an SiC block (Fig. 2.76). 

Bi Z, Zhou N, Zhong X. Relationship between composition and properties of MgO-spinel castables. Proc. Unified Inti. Tech. Conf. on Refractories. New Orleans, 33-39 (ACerS, Westerville, USA 1997). 

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