The corrosion resistance of samples made of low-cement concrete to a bottle glass melt was investigated in dynamic conditions at a temperature of 1350°C; they are used for production of articles used in glass-forming machines.The domestic refractory industry does not fully satisfy the needs of the glass industry with respect to the assortment and quality of most of the refractories manufactured for glass-melting furnaces [1 -3]. For this reason, glass works use furnaces in conditions of lower (sometimes by 1.5 -2 times) output of glass melt from the melting area or to increase output, purchase foreign high-quality refractories which are several times more expensive than the domestic analogs, which affects the cost of the products manufactured.The quality of the refractories in direct contact with the working media in the glass-melting furnace (roof, walls, bottom of the melting part, etc.) plays an important role in ensuring high-quality glass products. In addition to the refractories in the melting zone, the articles in the production part (feeder elements and glass-forming machines), which have a complex configuration with elevated requirements both with respect to performance characteristics and with respect to shape and size as a function of the application, have a large effect on quality. During their lifetime, refractories are exposed to the intensive effect of the glass melt and important thermal and mechanical stresses, so that they must have high glass and thermal stability, strength, and must also provide for constant assigned parameters of feed of the glass melt for processing and its temperature homogeneity [4].The production channel or feeder channel directly adjacent to the working part of the tank is designed for feeding glass melt to the feeder and then processing it by the glass-forming machine. The temperature of the glass melt in the feeder channel is 1000 -1350°C as a function of the type of glass. The concrete temperature is established to ensure a uniform decrease in it to the level determined by the viscosity of the glass melt required for forming. Defects in the form of stone, ripples, and seeds that enter with the glass melt and appear in reaction of the glass melt with the refractory lining cannot be assimilated directly in the channel by the glass mass. For this reason, the refractories for lining the feeder channel must satisfy certain requirements; the basic requirement is slow, uniform dissolution in the glass melt without formation of any defects.Many requirements are imposed on refractories used in glass-melting furnaces; the most important one is corrosion resistance to the glass melt (glass resistance) [5 -7]. The glass resistance, characterized by the rate of dissolution of a refractory in a glass melt, is a function of many factors: the chemical and mineral compositions and the structural features of the refractory, the chemical composition and viscosity of the glass melt, the surface tension on the boundary of the glass and the refractory, etc.In the domestic scientific and te...

Plastic mixes based on high-alumina chamotte HCBS and a multifractional refractory filler are prepared; the mixes molded at low pressures (30 MPa) make it possible to obtain materials with an initial porosity of 14 -15%. This effect is attained by adding a composite plasticizer (a refractory clay and a complex organomineral thinner) to the mix.Highly concentrated ceramic binding suspensions (HCBS) and HCBS-based plastic (plasticized) mixes are promising in the technology of unshaped refractories [1 -4]. From this standpoint, of special interest are high-alumina mixes.Efficiency of composite additives. It was shown in [5] that a highly dispersed refractory clay and a complex organomineral thinner (COMT) (composed of sodium tripolyphosphate and SB-5 organic plasticizer) when added to the high-alumina chamotte (75% Al 2 O 3 ) HCBS produced an exceptional thinning and plasticizing effect. Relevant illustrative data are shown in Figs. 1 and 2. The difference in porosity of green specimens free of COMT (Fig. 1a, curve 1 ) and containing COMT (curve 2 ) amounts to 2.5%. As the concentration of clay C is raised, the difference tends to increase, and at C = 3%, it reaches 8%. This difference is likewise retained in specimens heat-treated at 1000 and 1300°C ( Fig. 1b and c). The compressive strength of green and heat-treated specimens is likewise controlled by the clay concentration (Fig. 2). In clay-free specimens, the compressive strength s c does not differ much, 20 and 22 MPa (Fig. 2a, curves 1 and 2 ). With increase in C, curves 1 and 2 behave in a different manner; their course is quite clear and does not need detailed comment. Relationships compressive strength versus concentration C for heat-treated specimens are shown in Fig. 2b and c).It was noted in [5] that the high efficiency of the composite additive (COMT + refractory clay) is due to its ability to reduce the amount of kinetically bound liquid in HCBS-based systems.Elastoplastic viscous properties. Introducing highly dispersed refractory clays into "lean" HCBSs provides a route towards plastic mixes with quite satisfactory molding properties at relatively low molding pressure [1, 4]. The concentration of plasticized HCBSs may vary within 35 -45% (by weight) or within 40 -55% (by volume) depending on the HCBS granular composition, molding pressure, etc. In analogy with refractory castables [4,6], the moldability (placeability) of plastic mixes is mainly controlled by rheological properties of the matrix. Therefore it was of interest to explore rheological properties of HCBS in a flow state [5] and in a plastic state which is attained by partial dehydration of precursor HCBS.Our goal in this work was to study in some detail elastoplastic viscosity and structure-mechanical properties of precursor HCBS (free of additives) and HCBS containing additives COMT and refractory clay. Structural and mechanical properties of plastic mixes are typically characterized in terms of the yield limit, elasticity, plasticity, and plastic viscosity [7 -9].

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Refractory mixes of high alumina composition are developed for plastic molding. The mixes are distinguished from more traditional ones by a low clay content (by a factor of 3 -5) due to introduction into the mix composition of highly concentrated ceramic binding suspension based on high alumina fireclay that promotes an improvement in the basic physicomechanical properties of articles made from these mixes.It is generally known that there is a modern tendency to increase the relative proportion of the production and requirement for unmolded refractories and the balance of them [1]. Abroad there is very successful application of plastic refractory mixes both for making monolithic linings and for repairing them. It is well known [2 -4] that production of refractory air-hardening plastic mixes of aluminosilicate composition predominate. According to data in [4] the Al 2 O 3 content within them is 27 -90%, and for SiO 2 it is 6 -67%. Whereas the filler used in these mixes is fireclay, fractionated bauxite or corundum, clay is used predominantly as a binder. As a result of the fact that the clay content in these mixes is very significant their linear shrinkage during drying reaches 1 -1.4%, and 2.2% after heat treatment at 1100ºC [4]. The mechanical properties of these mixes both after drying and after heat treatment are relatively low. For a plastic mix from Plibrico with an Al 2 O 3 content of 27 -52% the ultimate strength in compression after drying and heat treatment at 1100ºC is 4 -7 and 14 -16 MPa respectively [5]; open porosity for the mixes after heat treatment is very marked (23 -30%).In view of this in the present work the task is set of developing refractory plastic mixes that compared with known mixes could be characterized by increased constancy of volume, density, and mechanical strength. The problem was resolved by using for the binder system plastic mixes of complex ceramic binder consisting of highly concentrated ceramic binder suspensions (HCBS) of the appropriate refractory material (for example aluminosilicate-fireclay or bauxite) and the optimum plastifying addition, i.e. refractory clay. This should provide an increase in concentration and a reduction of the water required for these mixes (since HCBS of acid and acid-amphoteric composition exhibit a low moisture content [1]) and shrinkage. In addition, for binder systems based on HCBS there is typically a marked increase in strength after low-temperature heat treatment [6]. It should be noted that the problem of plastifying HCBS of quartz sand [7] or bauxite [8] with refractory clay has been successfully realized as applied to a refractory mix formed by static compaction or pneumo(vibro)molding.Whereas in previous work for a ceramic binder and ceramic concrete [6 -9, 10] a detailed study has been made of rheological properties of the dispersed systems (original HCBS, filled suspension) in the flowing state, in this case the task has been set of obtaining refractory mixes not flowing, but of plastic (solid phase) consistency [11]. In studying the ...

Composite refractories and heat insulation materials of corundum, aluminosilicate and carbide ceramic compositions with improved operating properties have been prepared by modifying dispersed binder materials at different levels.

XRF method was used to study the mineralogical compounds of the radiation protection ceramic materials based on a high-alumina binder and a "heavy" aggregate, bismuth oxide. The content of Bi 2 O 3 in the test samples was kept in the range of 38.5-75 wt%. Along with the bismuth oxide, the aggregate was aluminum oxide (Al 2 O 3 ). The binder synthesis followed the principle of obtaining ceramic concretes based on artificial ceramic binders (ACB).The paper establishes the specifics of sintering of the composites under study, fired under different temperatures.