耐火材料对钢水杂质的影响

研究不同耐火材料在熔炼汽车用钢(IF)时对钢水中杂质的影响.研究含游离CaO耐火材料对全脱氧镇静钢(AR016)的净化作用.结果表明:用不同耐火材料熔炼时,钢水的杂质成分会发生变化.用镁碳耐火材料熔炼时,钢中C含量会明显增加.用镁铝耐火材料时,钢中Al含量会增加.用含游离CaO的镁钙耐火材料熔炼时,钢中杂质几乎不增加,而且对钢中某些元素,如:磷、硅、硫等还会有明显的降低,因此它是冶炼洁净钢用理想的耐火材料.     

Use in open-hearth roofs of periclase-chromite parts made from electrofused periclase-chromite

Conclusions A production test was made in the roof of a 180-ton open hearth of periclase-chromite parts produced by the Magnesite Combine from electrofused periclase-chromite.The life of the roof of experimental parts was an average of two campaigns of 690 heats, which is three times longer than the life of PKhS refractories produced by the Nizhnii Tagil Metallurgical Combine.The difference in the life of the two forms of refractories may be explained by features of their phase composition, structure, and failure mechanism.It was shown that the main improvement in the quality of the refractories is a significant reserve for increasing the life of open hearth roofs. The use in open hearth roofs of parts of electrofused periclase-chromite makes it possible to decrease the refractory consumption by 3.36 kg per ton of steel and to reduce the cost of a ton of steel by 0.05 rubles.It is necessary to continue work in the direction of production and use of refractories of pure sintered and fused original materials, especially in the local areas subject to the maximum wear of the roofs of open hearths in which high quality steel is melted.Translated from Ogneupory, No. 7, pp. 45–50, July, 1985.     

Tarred magnesite refractories for oxygen converters

Conclusions A technology was developed for producing tarred magnesite refractories for lining steel converters. The average monthly life of the lining of the converters at the ZSMZ was increased to 624 heats (August 1970) with a maximum life of 662 heats.The tarred magnesite refractories based on MDPK-75 powder possess excellent resistance to hydration and have a high strength. Considering these facts and also in view of the high capacity of the refractories division of ZSMZ it is possible to transport tarred magnesite products over appreciable distances and to deliver them to converters in newly constructed factories.The outstanding feature of tarred magnesite refractories is their slight tendency to slagging, in connection with which the life of the tarred magnesite linings largely depends on the daily output of the converters. To reduce the consumption of refractories in each converter at the ZSMZ it is necessary to arrange more than 30 heats per day during the entire campaign period.Translated from Ogneupory, No. 1, pp. 4–9, January, 1971.     

Refractories for handling steel outside a furnace

A range of refractories is presented for handling steel outside a furnace, which are produced by the Borovichi Refractories Corporation. The refractory characteristics and working features are given. Translated from Novye Ogneupory, No. 9, pp. 29–35, September, 2008.     

Production and use of refractory components for lining metallurgical plants and components for protecting the metal jet in continuous-casting machines

Experience is reported in making refractories and using them in sintering processes, blast furnaces, and steel melting, and the same applies to corundum-graphite components for protecting the metal jet in continuous-casting machines. __________ Translated from Novye Ogneupory, No. 4, pp. 16–23, March, 2007.     

IF钢生产用耐火材料的技术发展

概述了耐火材料在IF钢生产技术中的作用、应用状况和技术发展,并着眼于IF钢生产中最为关注的因耐火材料造成的钢水增碳、增氧和夹杂物缺陷等问题,论述与之相关的钢包内衬、连铸及中间包精炼和结晶器冶金中耐火材料的应用和开发方面所采取的应对策略和措施.     

Wettability of aluminosilicate refractories with molten steel

Conclusions An increase in the Al₂O₃ content of the base causes the wetting angle of steel 10kp to increase with an increase in the temperature from 1490 to 1620°C.Chromium-nickel steel wets refractories to a greater degree than rimmed steel. In this case the wetting angle is largest on mullite-corundum refractories containing 75–78% Al₂O₃.The introduction of small amounts of modifying additives in the form of MgO and Cr₂O₃+ ZrSiO₄ into mullite-corundum and corundum refractories causes the wetting angle to increase by 7–10° and helps to increase the resistance of the refractory materials to the action of rimmed steel.Translated from Ogneupory, No. 4, pp. 53–56, April, 1978.     

Resistance of refractories used in the high-temperature heat treatment of transformer steel

Conclusions The studies of various refractories after they have been heated in contact with transformer steel have confirmed that in order to increase the resistance of the hearth and reduce the amount of scale it would be sensible to heat the transformer steel to 1400°C in a medium of the products of incomplete combustion of natural gas with 0.5. For the linings of the hearths of continuous furnaces, it is possible to use refractories made from chrome-magnesite or magnesite compositions.Translated from Ogneupory, No. 3, pp. 51–54, March, 1979.     

Resistance of corundum refractories to basic electric steel slags

Conclusions Upon reaction with slag corundum specimens exhibit a substitution of corundum by calcium hexa and di-aluminates. This process occurs most intensely in the bond part of the refractory and over the periphery of the fragment of fused corundum.The temperature of the eutectic between CaO·2Al₂O₃ and CaO·6Al₂O₃ is 1730 ± 10°C, and corresponds to the operating temperature of refractories in the slag belt of electric furnaces.The formation of calcium aluminates around the fragments of corundum and in the bonding part tends to reduce the refractories of the altered zones of material and the wear by fusion. Therefore corundum refractories are not reccomended for lining the slag belt of electric steel smelting furnaces.Translated from Ogneupory, No.5, pp. 41–44, May, 1970     

Service experience of refractory products and mixtures in metallurgical plant lining at the Magnitogorsk Metallurgical Works

The authors describe the experience of production of refractories and mixtures and their service in blast furnaces and steel melting, as well as the service of corundum-graphite products for protecting metal strands on machines for continuous slab casting. __________ Translated from Novye Ogneupory, No. 8, pp. 9–11, August, 2007.     

In situ synthesis and interfacial bonding mechanism of SiC in MgO–SiC–C refractories

Adding SiC directly to MgO–C refractories possesses the disadvantages of low dispersion and interfacial bonding strength. Herein, the in situ synthesized SiC was introduced into the MgO–SiC–C refractories to maintain the original excellent performance of MgO–C refractories and reduce the carbon dissolution in molten steel. With the increase of Si and C content in raw materials, the morphology of SiC changed from whisker to network, whose growth mechanism was vapor–solid and vapor–liquid–solid. The network structure and uniform distribution of SiC improved the thermal shock resistance of MgO–SiC–C refractories. According to the analysis of molecular dynamics simulation by Materials Studio software, SiC strengthened the relationship between periclase and graphite to enhance the structure of the compound.     

Nanocarbon containing low carbon Al2O3–C refractories: Comparison between N220 and N990 nanocarbons

Continuous casting process is the majorly used solidification process in steel fabrication. The refractories used in this process are most commonly made up of alumina-carbon-based compositions. Generally, these functional refractories consist of about 30% residual carbon after coking. Improvements in steel industries, such as attaining clean steel and ultralow-carbon steel, require alumina-carbon refractories with low carbon content. In the present work, low carbon-containing Al₂O₃–C refractories are studied by using two different grade nanocarbons, namely, N220 and N990 with varying amounts, along with fixed 3-wt% graphite in the batch composition. The physical, mechanical, and thermomechanical properties along with the oxidation resistance are evaluated and compared. Phase analysis and microstructural developments at different temperatures were also characterized. Optimized compositions of both the nanocarbons are further studied for hot strength and oxidation resistance measurement. Based on all the obtained results, one batch composition is finalized for the thermal shock and corrosion testing. All the results are compared against a reference batch composition containing 25% graphite as a carbon source. The formation of in situ ceramic phases like aluminum carbide in nanocarbon-containing compositions provides a dense compact microstructure that improves strength, helps to inhibit oxidation, and contributes to corrosion resistance.     

Life of nozzles in continuous steel casting

Conclusions The lining of intermediate ladles should be heated up to 1300 or 1400° in order to prevent the steel cooling excessively and in order to reduce the thermal shock experienced by refractories when the metal is being tapped.The best results in continuous pouring of boiling steel are shown by chamotte nozzles with high-alumina inserts, and these are recommended for use.In the continuous pouring of killed steel, the least filling in is observed in chamotte nozzles with zirconium inserts and with a clay-graphite layer; the clay-graphite layer, nevertheless, wears out more easily and this gives rise to an increase in the steel pouring rate.The main reason for the closure of the stoppers is the formation on the working surface of a vitreous crust containing mullite, corundum, spinel formed by the aluminum added to deoxidize the steel.     

A novel approach to prepare graphite nanoplatelets exfoliated by three-roll milling in phenolic resin for low-carbon MgO-C refractories

Development of nano carbon containing magnesia graphite refractories to reduce the total carbon content is urgently required for application of low carbon steel smelting. In this work, a novel approach to prepare graphite nanoplatelets (GNPs) by exfoliating flake graphite (FG) in the medium of phenolic resin (PF) via three-roll milling, and the as-prepared GNPs/PF mixtures were used in MgO-C bricks to develop a novel low carbon magnesia-carbon refractories (LCMCRs). The results show that with the increasing of exfoliation times, the FG was constantly thinned, and the production of GNPs had thicknesses of 10–20 nm after exfoliation for 16 times. As a carbon source for LCMCRs, the GNPs and/or GNPs/PF mixture with 2 wt. % carbon could improve the comprehensive performance of the LCMCRs, including the higher cold crushing strength and hot modules of rupture, the better oxidation resistance and slag corrosion resistance. The GNPs continue uniformly dispersed and wrapped with magnesia aggregate, playing an importance role and positive impaction on the corrosion resistance of refractories.     

Formation of liquid-phase isolation layer on the corroded interface of MgO/Al2O3-SiC-C refractory and molten steel: Role of SiC

Formation of a dense layer on corroded interface to suppress corrosion is always desired, but it is controlled by numerous environmental conditions. In this work, corroded microstructures of MgO/Al₂O₃-SiC-C refractories in metal bath area of ladle furnace were investigated after industrial trails. A liquid-phase isolation layer in which MgO islands and liquid phases was established on the corroded interface of refractories with 6 wt% coarse/fine SiC-additive. The formed isolation layer against steel/slag attacks led to an approximate 30% improvement in corrosion resistance than that of refractory with 3 wt% fine SiC-additive. More importantly, the liquid-phase isolation layer blocked the direct mass transfer between molten steel and refractories while it decreased exogenous pollution from refractories. SiC-additive affected the formation process of isolation layer by controlling the generation/migration of Mg(g) on refractory' surface. A further formation mechanism of liquid-phase isolation layer was discussed in detail and role of SiC was elucidated.     

Refractories for the slide gates for molten steel

Conclusions A variety of refractories were subjected to testing in the slide gate of a 3-ton ladle. Nonoxygenous refractories are unsuitable for steel casting either because their thermal conductivity is too high or because they are not strong enough. Oxygen-containing materials developed cracks during the pouring operation so that they could be used only once.The refractories recommended for testing in a large-capacity ladle were periclase. corundum, and zircon types.The best results were obtained with periclase plates which permitted an entire melt to be poured within 1.5 h, during which the jet of molten steel was shut off 23 times.Translated from Ogneupory, No. 7, pp. 34–38, July, 1976.     

High-alumina refractories for lining steel ladles (discussion)

Conclusions We developed and evaluated, in industrial conditions, a technology for the production of unfired, mullite-corundum refractories, and also fired, mullite-siliceous refractories with additons of chrome ore for lining steel ladles.The life of the 150-tonne steel ladles, with steel processing outside the furnace, when the ladles were lined with the experimental unfired mullite-corundum refractories, equals the life of the ladles lined with similar, industrial fired bricks. The same resistance (on average 20 pourings) was possessed by the ladles lined with the experimental mullite brick of improved quality. The resistance of the ladles lined with the experimental, fired mullitesiliceous refractory with the chrome additive was 26–27 pourings.To explain the effectiveness of using the newly developed refractories in the linings of steelcasting ladles, it is necessary to continue testing them in different metallurgical enterprises.The first part of the discussion was published in No. 8, 1988, and it was continued in Nos. 9–12, 1988, and Nos. 1–3 and 5, 1989.Translated from Ogneupory, No. 7, pp. 4–8, July, 1989.     

Competitiveness of products: A key to success in an incipient market economy

The Borovichi Refractory Plant has organized the production of new advanced refractories, including graphite-containing articles for continuous casting of steel, a variety of mullite-corundum articles, mortars, and refractories for lining blast furnaces. The prospects for refractory production are considered. Properties of the new refractories and data on their use in the metallurgical industry are presented.Translated from Ogneupory i Tekhnicheskaya Keramika, No. 8, pp. 23–26, August, 1996.     

Service of refractories in continuous casting of stainless steel

Conclusions Work was done on studying the service of refractories in continuous casting of stainless steel.It was established that refractories produced by domestic industry are suitable for this process and make it possible to obtain continuously cast billets in accordance with the requirements of TU 14-105-469-83. Gas protection of the stream of metal causes additional refining of the metal of nonmetallic inclusions and makes it possible to increase the quality of the cast billet.Stream treatment of the metal with inert gas makes it possible to significantly reduce encrustation of the nozzle channel with products of interaction of the molten metal with the refractory material of the ladle nozzle.Translated from Ogneupory, No. 6, pp. 52–55, June, 1985.     

Use of unfired periclase-carbon refractories in parts of linings of 350-ton steel-teeming ladles

Workers of the Azovstal’Company have established the causes of the decrease in the endurance of slag-line areas of linings of 350-ton steel-teeming ladles. In 1995–1996 they conducted industrial tests and introduced a process for lining the slag areas of 350-ton teeming ladles with unfired periclase-carbon refractories. The mean service life of a lining of a 350-ton teeming ladle with a slag line made of periclase-carbon refractories amounts to 23 heats on the average without hot repairs of the slag line during the campaign. The wear of the periclase-carbon lining in the slag line is 3.6–4.3 mm per heat. The specific consumption of refractories and materials for a lining has been decreased by 0.6–0.8 kg per ton of converter steel. Such an operating capacity for the periclase-carbon refractories in slag lines is provided by the composition and structure of the refractories, which possess a high heat resistance and resist the effect of the molten metal and slag. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 2, pp. 37–39, February, 1998.