Diffusion kinetics in contact of electromelted corundum refractories with the glass melt was investigated. The diffusion coefficients of Al 3+ and their temperature dependence were determined. The basic tenets of diffusion kinetics in service of refractories in glass furnaces and feeder channels are examined.Electromelted refractories are predominantly used in the glass industry. Corundum refractory articles are highly recommended in lining for the feeder channels of glass molding machines. Their high stability at the temperatures of preparation of the glass melt for molding ensures a long lifetime and prevents the appearance of glass flaws in the finished products.At the same time, the complex process of the reaction of refractories with the glass melt, including surface phenomena, chemical reactions, transfer phenomena (diffusion, viscous flow, heat transfer) and other factors has been insufficiently investigated. This especially concerns diffusion phenomena; the information on the diffusion coefficients of different ions is limited and primarily concerns diffusion of Na + ions at low temperatures [1].Experimental methods. Samples of electromelted corundum refractories were used for the study (mass content, %): 1) 100 Al 2 O 3 ; 2) 96.50 Al 2 O 3 , 2.65 SiO 2 , 0.41 Na 2 O, 0.05 K 2 O, 0.12 Fe 2 O 3 , 0.27 other oxides. Composition of the glass (%): 75 SiO 2 , 10 CaO, 15 Na 2 O. The experiments consisted of melting glasses of the given composition, obtaining data on the viscosity and density of the glasses with consideration of dissolution of the refractories, determination of the concentration ratios in dissolution, the diffusion characteristics, etc.To study corrosion of the refractories in the glass melt, different static and dynamic methods were used [2] which allowed obtaining a comprehensive evaluation of the glass stability of the refractory materials without separating the individual constituents of the process. The methods are relatively graphic in conducting comparative tests of samples of refractories using the same experimental setup. Comparable results cannot be obtained on different setups, so that theoretically substantiated methods of diffusion kinetics in moving media for different conditions were used to study the diffusion characteristics in reaction of the refractories with the glass melt.Such methods are the rotating disk method (sample of the investigated refractory) ensuring the perpendicularity of diffusion flow to the surface [3,4]. When this method is used, the following picture of movement of the liquid is observed. Ascending flow to the disk is observed at a sufficient distance from the rotating disk, and in the layers immediately adjacent to the disk, the liquid acquires rotational motion, and the angular velocity increases in approaching the disk, to a value equal to the angular velocity of the disk itself. The rotating disk has an important feature that ensures equal accessibility of the surface with respect to diffusion, which is very important for real solids whose surface is us...

The service conditions of refractories in feeder channels is analyzed. The prospects of using electromelted corundum refractory products for feeder trays are analyzed based on their operation practice at some Russian glass factories.Electromelted refractories are commonly used in the glass industry, mainly for the brickwork of glass-melting tanks [1]. Feeders of glass-forming machines were mainly produced from sintered high-alumina (sillimanite, mullite) refractories [2]. Lately, in view of intensified glass-melting and glass-forming processes, electromelted refractories with increased glass resistance are receiving wider acceptance in using high-efficiency glass-forming machinery.It has been established in comparative tests that the glass resistance of melted mullite refractories is higher than that of sintered refractories of the same composition: 3 times higher for soda-lime glass, 2 times higher for borosilicate glasses, and equal to lead silicate glass.The application of electromelted corundum and baddeleyite-corundum refractories is limited due to their insufficient thermal resistance, which prevents using them for some feeder parts, such as plungers, cylinders, shut-off plates, or burner stones. At the same time, electromelted corundum refractories are promising for feeder channel trays, providing their vitreous phase content is significantly decreased, since it may be a source of defects in products (stria, bubbles, stones) when glass melt is prepared for forming [3].The resultant velocity of the corrosion of refractories depends on the velocity of the limiting stage in the process. When a refractory reacts with a highly viscous glass melt, such limiting stage is diffusion. The above general statements are completely true of the corrosion of refractories in feeders.The relatively low temperature in feeders and, accordingly, the high viscosity of glass melt decrease the aggressiveness of the melt and the diffusion coefficient. At the same time, increased glass melt velocities in feeder channels facilitate the removal of products from the chemical reaction zones and shift the physicochemical equilibrium in the refractory -glass melt system; in this case the melt dynamics to a certain extent determines the rate and the depth of destruction of refractories by mechanical impact on the chemically weakened refractory. Figure 1 shows the variation of glass melt velocities along the feeder and across it depth based on data from [4]. The velocity and temperature profiles across the channel width and depth are parabolic along the entire channel length, which is due to natural cooling of the glass melt near the refractory surface. The temperature maximum is registered at a depth of 1 2 H. The shapes of the velocity and temperature profiles in the cooling zone and in part of the conditioning zone are slightly different; moreover, the maximum velocity is observed on the glass melt surface, whereas the

The main factors associated with the service of refractories mainly in the melting tanks of glassmaking furnaces are examined. The main technological factors, a description, and the scheme of the technological cycle for the production of refractories at the Domodedovo Plant for Manufacturing Electro-Smelted Articles are presented.In glassmaking the quality of refractory materials is of great importance because it determines the glassmaking capacity, the service life of the glassmaking furnace, and the product quality.In the overwhelming majority of the cases, commercial refractory articles contain, aside from a high content of a crystalline phase, some amount of a glassy phase. The properties and operating characteristics of refractory materials differ substantially depending on the type and content of the crystalline and glassy phases. The important factors here are the chemical (corrosion) and heat resistance and mechanical strength. As a rule, many flaws in molten glass appear as a result of unforeseen breakdown of refractories during the operation of a glassmaking furnace. This is especially true for electro-melted bacor articles used for the melting tank of glassmaking furnaces, which are subjected to action of the glass melt and high temperatures [1 -3].Types of Refractory Materials and Their Application. The refractory articles used in glassmaking are classified as follows:by chemical composition -alumino-silicaceous (fireclay, high-alumina), silicic (dinas, quartz), corundum, baddeleyite-corundum (bacor), chromium-containing, magnesitic (with additions of Al 2 O 3 , ZrO 2 , Cr 2 O 3 ); by technological manufacturing method -ceramic, obtained by sintering, and melted, obtained by casting from melts.For the elements of the domestic glassmaking furnaces, used in the production of the largest articles from glass (sheet glass, glass containers, dishware, and others), the following types of refractories are used:bacor -melting tank, channel, and other critical elements;bacor -burner entrances, elements of the walls of the flame space; dinas -main crown, elements of the walls of the flame space;bacor and corundum -outflow channels, feeder channels, drop-forming parts; magnesitic -hood of the regenerative chambers (top rows).Service of Bacor Articles in Glassmaking Furnaces. Many factors determine the time period between maintenance for glassmaking furnaces: the properties of the refractories used (heat and corrosion resistance), service conditions of individual elements of the refractory masonry (cooling, insulation), parameters of the technological melting regime (temperature level, extraction of the molten glass, type of fuel, organization of fuel combustion), and structural particulars of the glassmaking furnace.Reasons for premature breakdown of refractories. First and foremost, these are: deviation from the rules for optimal arrangement of refractories;disruption of the heat-engineering regime of the furnace during extraction and operation: global or local temperature rise, sharp temperature differentials, ...

The physical-chemical interactions at contact of molten glass with refractories in a glassmaking furnace, mostly electricity melted baddeleyite -corundum (bacor), are examined. Three basic interactions are discussed: surface phenomena, chemical interactions, and transport phenomena.Glassmaking and the preparation of molten glass for molding are conducted in refractory tanks and feeders. High temperatures and complicated physical-chemical interactions in the contact zone destroy the refractory masonry and result in the appearance of different types of flaws on the molded glass articles.In what follows the interaction of glass melts, having the most common compositions (sheet glass, glass containers), with baddeleyite-corundum (bacor) refractory melting tank of a glassmaking furnace is examined.The characteristic features of the contact phases are: -the glass melt at high temperatures is a chemically active ionized liquid with high viscosity and surface tension, exhibiting nonuniformity of the composition, properties, and structure;-the structure of the refractory materials is represented by microparticles of the crystalline phase, cemented by a refractory glassy phase; the rough surface of refractories has the capability of adsorbing various compounds from gases, vapors, and liquids; as a result of the nonuniformity of the composition, properties, and structure of the refractory materials, they breakdown nonuniformly in a glassmaking furnace.The interaction of the molten glass with the refractories of a glassmaking tank determines the service life of the glassmaking furnace and the quality of the glass. This is mainly due to the quality of the refractory materials but the character of the interaction is determined by complicated complex processes occurring at the interphase boundary, including:-chemical interaction; -surface phenomena; -transport phenomena. These processes result in the formation of a "meso-layer" with thickness~10 -3 m. Marked surface, chemical, and ionic-diffusion phenomena are observed in the direct contact zone (thickness~10 -5 m). As the thickness of the "mesolayer" increases, the convective components of the transport phenomena begin to manifest together with shearing deformations.Ordinarily, works devoted to the corrosion of refractory materials examine the overall interaction picture, which is associated with the glass stability of refractories of the glass-making furnaces. Individual components of the interaction of refractories and the molten glass have also been studied. The key information on these directions is contained in [1 -6]. CHEMICAL INTERACTIONSThe tanks of glassmaking furnaces are constructed from baddeleyite (bacor) refractory beams. The chemical composition of bacor is close to the eutectic region of the ternary system Al 2 O 3 -ZrO 2 -SiO 2 [7] (Fig. 1). The structure of bacor is characterized by aggregate concretions of baddeleyite and corundum crystals, which largely determine the resistance of refractories to glass melts. However, when melted refractories are prepared t...