Wettability of aluminosilicate refractories with molten steel

Results of a study of the wettability of the tundish periclase lining by molten steel using a sessile drop method are presented. The wetting angle q tends to decrease with increase in temperature and contact time on adding glass fiber and Fe 2 O 3 powder in excess of 2% to the magnesite powder; a similar effect is observed in steels high in manganese. An increase in angle q is observed on adding carbon fiber or glass fiber (not in excess of 1%) to the magnesite powder; the angle q tends to increase with increase in MgO powder grain size and with carbon contained in steel in excess of 0.04%.In recent years, there has been an increased demand for steels with a low impurity content. Technologically, the tundish ladle is the last refractory-lined vessel in which the molten steel is processed metallurgically before pouring into molds. MgO-based refractory materials are preferred for making the hot layer of the refractory lining of the tundish ladle. To increase the strength of the lining (normally applied using a gunning technique), additives are introduced into the gunning mix -paper fiber (coarse-or fine-fibrous), mineral wool, glass fiber, expandable clay, and polystyrene beads [1 -3].The interaction between tundish lining and molten steel and slag is an important concern for manufacturing high-purity steels. This interaction involves two related phenomena: wetting and reaction between the three components, which determines the service life of the refractory and the properties of molded preforms, slabs, and blooms [4,5]. To determine the wettability of a solid substrate by molten metal, Young's equation is conventionally used [6]:where q is the wetting angle, deg; g SV is the surface tension of the solid; g SL is the energy of surface interaction between the liquid and the solid; g LV is the surface tension of the liquid. As is known, the liquid wets the solid if q < 90°; in unwettable systems, it is q > 90°.Data have been reported on the wettability of various refractory surfaces [7 -21] by molten iron and steel [7 -9] and on their interaction with gas media [7 -9, 11, 21] and molten slag [7 -9].In [13 -16], the wettability of aluminosilicate refractories by steel or iron was studied; in [17], the effect of Steel 35 on corundum composites was studied, and in [20], the wetting angle q at zirconium surfaces and molten iron was measured. MgO is the most widely used material for manufacturing the tundish lining; still, data on the wettability of periclase lining by molten steel and the effect of additives on wettability are sadly lacking [7,22]. Therefore our goal in this work was to study the wettability of MgO by molten steel. EXPERIMENTALThe low-carbon steels were made available from the Eregli Iron and Steel Works (Turkey); their composition is given in Table 1. The tests were carried out by a sessile drop method; the test specimens were cubes of steel weighing about 0.3 g; the substrate was a magnesite powder of composition, wt.%: MgO, 95.08; SiO 2 , 2.49; CaO, 1.73; Fe 2 O 3 , 0.54; Al 2 O 3 , 0.16. The powde...

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“…10). This is explained by the surface tension of molten steel decreasing with temperature, in agreement with the literature data [8,13,15,17].…”

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Wettability of tundish periclase lining by steel

et al. 2006

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“…For the more complete characteristics of the chamotte parts the heat resistance, thermal conductivity according to the method of [5], and boundary angle of wetting by the metal in relation to heating temperature [6] in comparison with high-alumina and periclase parts were also determined.…”

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Experience in the use of chamotte nozzles in slide gates in teeming of stainless steel

et al. 1985

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The Ukrainian Scientific-Research Institute for Refractories together with the Dnepr Special Steel Electrometallurgica! Plant has conducted investigations [1][2][3][4] on the development and selection of refractory materials for slide valve parts in teeming of bearing and stainless steels, which are prone to clogging of the steel-teeming channel, for the purpose of providing stability in operation of the valve, a reduction in crust formation, and an increase in the times of use of the plates, nozzles, and well blocks.The service tests of mu!lite--corundum, mullite, and kaolin refractories showed that they answer these requirements since in use of them because of the reduced thermal conductivity in comparison with periclase parts there is a reduction in crust formation and clogging of the steel teeming channel and the teeming process is more regular without a reduction in steel quality [2,4].This article presents experience in the production of chamotte nozzles and nozzle collectors and service of them in the slide gates of steel-teeming ladles of stainless steel at the Dnepr Special Steel Plant.The parts of the experimental lot were produced at the Zaporozhe Refractory plant from the raw material used in the production of chamotte refractory parts, ShKGP chamotte, PLK-0 kaolin, and DN2 clay.The charge for the molding mixture consisted of granular chamotte with a water absorption of 3% containing about 39% A1203 and a mixture of ground kaolin and clay. The mixture, with a moisture content of about 6%, was prepared in mixing mills using the normal plant method for 4 min. The nozzles (No. 13) and the nozzle collectors (No. 23) with a height of 250 and 300 mm and a channel diameter of 80 and 60 mm, respectively, were formed on a 6.3MN hydraulic press under a pressure of about i00 MPa in two stages with premolding from below in view of the significant height of the part.The apparent density of the freshly formed raw material varied within limits of 2.20-2.25 and 2.13-2.16 g/cm 3 for the nozzles and the nozzle collectors, respectively.The parts were dried and fired in a 120 m long tunnel kiln with a maximum temperature of 1400~ The nozzles were placed on the kiln cars in the vertical position on a base of chamotte brick in two rows with one part of the upper row on four of the lower with the large diameter downward. The properties of the chamotte SHS-32 nozzles and the nozzle collectors met the requirements of Technical Specification 14-8-385--81 (Table I).For the more complete characteristics of the chamotte parts the heat resistance, thermal conductivity according to the method of [5], and boundary angle of wetting by the metal in relation to heating temperature [6] in comparison with high-alumina and periclase parts were also determined.The thermal conductivity of the slide gate parts is an important property in teeming of stainless steel.It is known [i, 2] that the intensity of formation of the crust on the walls of the teeming channel is in relation to the thermal conductivity of the refractory material.It has be...

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Wettability of aluminosilicate refractories with molten steel

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Wettability of tundish periclase lining by steel

Wettability of tundish periclase lining by steel

Experience in the use of chamotte nozzles in slide gates in teeming of stainless steel

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