Sliding gates are becoming more and more widely used in steel casting in Soviet steelworks. Experience of the use of these gates is constantly being analyzed. On the basis of these analyses, the specifications for the refractory materials are refined and the operational conditions during casting improved.The main factor determining the reliable operation of the gates is their metal resistance, i.e., the ability of the material of the refractory tiles to withstand the aggressive action of liquid steel. From 30 to 5(f/o of unsatisfactory castings arise from factors associated with the development of excessive interaction between the tile material and the components of the liquid steel [1].

The refractory lining in which a metal is smelted has a significant effect on the properties of the metal.An equilibrium concentration of oxygen, which depends on the chemical nature of the crucible material, is established in the molten metal when subjected to a long dwell in the crucible [i]. Under actualconditions, the induction crucible furnace with intense electromagnetic perturbation and a relatively large specific interface surface between the metal and lining, which helps to bring the system (metal-lining) rapidly to the thermodynamic equilibrium, is close to this laboratory situation.It was shown [2] that a metal with a small concentration of vanadium, which is active towards oxygen, more quickly establishes equilibrium with the lining and the concentration of oxygen in it on melting than the same metal without vanadium.The concentration of nitrogen is related to the concentration of oxygen in the metal on melting and this is explained by the difference in surface activity of oxygen and nitrogen at the metal-atmosphere and metal-lining interfaces.Oxygen being the more surface-active element is absorbed in the surface layer of metal and occupies the adsorption centers, thus preventing the removal of nitrogen [2].It was shown in [3] that the role of the metal-lining surface is also active in the deoxygenation and doping of the metal.Thus the existing facts indicate that refractory oxides can be used as sorbents for the removal of oxygen from a liquid metal.There is virtually no data in the literature relating to the sorption tendency of refractories.Therefore the aim of the present study was to investigate the oxygen-sorption behavior of periclase and corundum.The specimens of refractory were prepared in the form of substrates 18 mm in diameter and 5 mm thick and as crucibles to contain 0.25 kg of metal.Refractories of different porosity were obtained by selecting the grainy composition of the original refractory powders and by the use of different pressing pressures and firing temperatures.As the original materials we used fused periclase with a 92.50%* concentration of MgO and corundum with an AI20~ concentration of 96.84%; to the masses we added 1.5% of boric acid.In the experiments we also used corundum and periclase single crystals.The open porosity of the periclase refractories was P~ ~ 27%, P2 ~ 23%, and P3 ~ 21%; of the corundum specimens, P~ ~ 26%, P~ ~ 24%, and P~ ~ 20%.The metal for the experiments (the 80N alloy) was melted in an open induction furnace with a 15-kg capacity magnesite crucible by alloying carbonyl iron with electrolytic nickel, grade NI.Forged and turned metal was remelted in a vacuum induction furnace in a corundum crucible.The characteristics of the metal used a=e given in Table i.The turned metal specimens were stored before the experiment in weighing bottles contain ~ ing carbon tetrachloride.The wetting experiments were carried out on the apparatus described in [4] at 1490~ in an argon medium with a 99.997% concentration of the main metal and 0.0003% of oxygen.The argon w...

.046.518 and V. P. Karasev An analysis of the operation of steel-teeming slide gate plates showed that to a large degree their life is determined by the operating reliability of the gate and depends upon the service conditions. The difference in properties of refractories used for production of the plates and the variety of operating conditions make pressing the rational selection of the form of refractories in relation to the conditions of their use.The thermal action of the molten steel causes the occurrence in a 10-20-mm-deep surface layer of very high gradients in the temperature field. Even 5-15 sec after contact with the molten metal the temperature gradient reaches the maximum value, which at a depth of 1-3 mm is 250-350~ 5-10 times greater than the failure gradient of periclase and corundum refractories [I].During teeming in operation of the gate the temperature field changes, but for a long time the temperature gradient changes but exceeds the limiting value. The greatest variations in temperature occur in the supporting portion in relation to the metal of the lower movable plate, which is responsible for reliable shutting off of the stream. The more shut-offs during teeming, the more intense the thermal action of the molten metal on the contact layer of the refractory. Corundum refractories are 1.5-2 times more heat resistant than periclase. Therefore, for gates for teeming on a continuous billet casting machine it is desirable to use periclase refractories, and in top teeming into molds corundum refractories.The essence of the corrosive action of molten steel on the gate plate material consists of spontaneous liberation on the contact surface of endogenic oxides of the primary oxide phase of the molten metal and subsequent development of the chemisorption process. The composition of the primary oxide phase is determined by the type of steel melted and the method of deoxidation of it. Depending upon the composition of the primary oxide phase the oxides precipitated may be in the liquid or solid state [2]. Steels containing flowable components of the primary oxide phase of the FeO-MnO-Si02 system, which are characteristic of rimmed and semikilled steels, are the most aggressive toward the refractory. Corundum refractories possess a lower resistance toward the corrosive action of such steels than periclase. Therefore, for teeming of them it is desirable to use periclase refractories. Since with an increase in temperature and contact time the corrosive action increases, for teeming on a continuous billet casting machine and teeming of large heats it is also desirable to use periclase refractories.Killed carbon steels are deoxidized with a somewhat larger quantity of silicon and sometimes aluminum is used. The oxide components of such molten steels are most frequently solid phases. In these cases there is not capillary penetration causing significant development of the depth of the reaction layer, and corrosion of the refractory is practically absent. In teeming of such steels the selection of the refractor...

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