Quartzites for crucibles and methods of lining crucible induction furnaces (Review)

Conclusions With observation of the requirements of chemical and grain-size compositions, progressive methods of lining work, and sintering of the crucible, domestic quartzites provide a long lining life of induction crucible furnaces in melting of iron and sufficient life in melting of carbon steel.Translated from Ogneupory, No. 6, pp. 48–52, June, 1985.     

Effects of mixture composition on the lining stability of a crucible induction furnace

Research results are reported on the effects of components on the resistance of acid lining for the crucible induction furnace. To raise the lining resistance, one needs to eliminate components that react with the silica crucible. The extent of silicon reduction from the lining is dependent on the heating of the metal and the contents of carbon and silicon in the liquid. Increasing the carbon content and reducing the silicon concentration in the metal favor wear on the crucible. The slag components most actively influencing the resistance of the lining are magnesium and calcium oxides, which are produced on modifying cast iron, ferrous oxide, and manganese on account of reduction in the viscosity of the slag, increase in its wetting power, and penetration into the pores and unevenness in the walls of the crucible. Translated from Novye Ogneupory, No. 5, pp. 41–43, May, 2008.     

Manufacture and service of induction furnace crucibles made of magnesite with sintering additives

Conclusions The use of rammed magnesite masses with sintering additives in the lining of induction furnace crucibles makes it possible to increase their strength by a factor of two or three. The sintering additives recommended are cheap and easy to obtain, and the procedure for ramming crucible linings is simple.     

Effect of Melting Temperature Regimes on Change of Interplanar Distance in Quartzite

Refractories and Industrial Ceramics - The reliability of an industrial frequency crucible (IFC) induction furnace, used in casting manufacture, depends on its lining life. For this reason...     

Refractory for lining induction furnaces

Conclusions Studies established that the lining body made from Karel'sk quartzites is not inferior to the Swedish material used for lining induction furnaces by many foreign companies.The great reserves and favorable mining conditions for obtaining these materials enable us to examine quartzite from the central Karel'sk area as raw materials for producing the lining bodies of induction furnaces.Translated from Ogneupory, No.5, pp.39–42, May, 1972.     

Corundum-Based Mixtures for Refractory Lining in Ferrous Metallurgy

The development and industrial applications of new corundum and bauxite-based mixtures for the refractory lining of iron-melting units (furnace, crucible, ladle), and a new mortar for refractory brickwork, are reported.     

Behaviour of spinel-forming DVM using crucible induction furnaces. A case study on material failure

This article contributes to the understanding of the sintering behaviour of spinel forming dry vibrating mixes (DVM) that are in common use in crucible induction furnaces (CIF) for metallurgic treatment. At present, an unwanted sintering of the DVM as far as to the cold face is reported from the industry. For safety reasons it is indispensable that an unaffected layer is remaining at the cold face of the lining. If not, the material becomes brittle and the risk of crack formation gets unacceptable. The access of liquid melt to the induction coil may cause severe accidents that destroy the furnace which bears the risk of industrial injury.Systematic research on breakout materials by means of SEM-supported microtextural and microanalytical investigations come to the result that a sintering occurs already in areas of the lining where the prevailing temperature could not have exceeded 300 °C. Furthermore, it can be carved out that the sintering at the cold face is caused by the formation of spinel. This result is in contradiction to the generally accepted opinion that the spinel formation is kinetically hampered at temperatures lower than 900 °C and should not occur. The increased MgO:Al2O3 ratios of the newly formed spinels indicate lower crystallization temperatures. The gradual transformation starts with marginal dissolution of the magnesia grains at the cold face and progrades with the development of skeleton structures of matrix spinels.The spinel formation is favoured of different components as chemical additives, a reduced atmosphere, hydration, and a momentary overheating. However, it is suspected that water and short-term overheating, respectively, play the key role since other known major agents as untypical oxides, and in particular fluorides and chlorides can be excluded by their erratic occurrence. We identified water as a primary unwanted additive which left typical microstructures in magnesia grains of the studied lining breakouts.     

Service conditions and improvement of the lining of vacuum induction furnaces

Conclusions A study was made of the temperature conditions in the lining of 1.0 and 2.5 ton vacuum induction furnaces. It was established that after the fourth heat the temperature conditions are stabilized and the values of the temperature gradient and the temperature at different distances from the working surface of the crucible were obtained.A design of vibropacking unit was developed making it possible to accomplish uniform packing of the crucible lining simultaneously over the whole volume.The failure stresses in the lining were relieved by introducing into its composition coarse grained corundum and by packing the mass by vibration over its whole volume.Translated from Ogneupory, No. 6, pp. 29–32, June, 1982.     

Pervoural'skii and Karel'skii Quartzites for the Lining of Crucible-Type Induction Furnaces

Requirements placed on the quartzite-based lining of crucible-type induction furnaces are discussed. The properties of Pervoural'skii and Karel'skii quartzites (P- and K-quartzites) are studied. Mineral impurities (in particular, mica) and their effect on properties of quartzite mixtures are considered. Industrial tests show that the fine-grained, predominantly intergranular mica is mainly responsible for the high wear resistance of K-quartzites. A characterization of the Metchangjarvi quartzite deposit is given and its commercial potential for production of refractory materials is discussed.     

Effect of Quartzite Heat Treatment on Induction Furnace Lining Failure Mechanism

Refractories and Industrial Ceramics - The wear mechanism of a quartzite lining of induction crucible furnaces during iron and steel smelting is presented. It is established that the main cause of...     

Production of Periclase-Carbon Refractories at Semiluki Refractory Plant

The technology and commercial production of periclase-carbon articles with a regular grain composition from a raw material with unstable grain size are described. A comparative study of casting, elemental, and crucible graphite as the basic carbon component has shown that the best commercial properties are provided by the use of crucible graphite. Tests of periclase-carbon refractories without metallic aluminum and with various contents of aluminum have shown the possibility of a differentiated approach to the use of the antioxidant with allowance for the specific service conditions of the lining.     

A high-alumina lining for crucible-type induction furnaces

Conclusions In crucible-type induction furnaces, the durability of a lining of compound MLM-1 (Technical Specifications 14-8-119-74) is several times higher than that of a quartzite lining or a sintered lining based on corundum and kyanite-sillimanite concentrate. The compound can be recommended for crucible furnaces when melting high-grade cast iron and steel.The density of compound MKE-78 can be increased by adding up to 20% synthetic corundum No. 6 and 3–4% orthophosphoric acid solution. Its high refractoriness makes it possible to use this lining as well for melting steel with a casting temperature of 1680–1700°C Its durability in this case is at least 2 months.Translated from Ogneupory, No. 3, pp. 24–28, March, 1977.     

Interaction of zirconia refractories with molybdenum ingots in induction furnaces

Conclusions The oxidation of molybdenum ingots during heating in an induction furnace may be the result of the loss of oxygen from the zirconia and the liberation of gases from the lining but it should not be significant at 2000–2100°C in a furnace sealed airtight. The interaction of the metal with the refractory lining proceeds through a gaseous phase and is the result of the vaporization of the molybdenum oxides which are formed when air enters the furnace, while the ingot is placed in it and is subsequently not replaced by argon.Translated from Ogneupory, No. 4, pp. 38–42, April, 1978.     

无芯感应炉用炉衬材料的选择

介绍了感应炉炉衬耐火材料的使用环境 ,分析了感应炉炉衬结构以及在不同的使用环境下的使用情况和材料选择     

CaZrO_3耐火材料的制备及其与钛合金熔体的界面反应

合成了一种CaO-ZrO_2系复合耐火材料,用模压法成型,分别在1 650℃和1 680℃烧结制成坩埚.使用此坩埚在感应炉中熔化钛合金(TiNi),在真空条件下, 1 500℃保温5min.对在1 680℃烧结成的坩埚进行了抗水化性能测试.用X射线衍射仪对CaZrO_3材料进行物相分析.用扫描电子显微镜观察钛合金与此材料的界面反应层的微观形貌,结合能谱仪进行微区成分分析.结果显示:1 680℃烧成的CaZrO_3材料具有良好的抗水化性;用此坩埚熔化TiNi合金后,液态钛合金和耐火材料的界面反应层厚度约为30μm,界面反应层中,Ca,Zr,Ti,Ni等元素无明显扩散.     

Experience of using mixture KSVKh-1 in induction furnaces at the AMO ZIL Works

The service results of submerged-resistor induction furnaces for pig iron exposure of the vertical (capacity 30 tons) and horizontal (capacity 60 tons) types at the AMO ZIL Works are described. The furnace lining is made of KSVKh-1 corundum mixture by casting. The lining is found to be reliable in service, and its resistance is more than two times higher than that of mixture MK-90. __________ Translated from Novye Ogneupory, No. 5, pp. 13–14, May, 2007.     

Phase composition of the products of encrustation of the channels of magnetodynamic feeders for aluminum alloys

Conclusions The investigations made it possible to establish the composition of the crust and the influence on its formation of certain service factors. In operation of MDN-6A feeders encrustation of the channels has a local character. The crust is formed in one of the side vertical portions of the channel. Failure of the crucible lining, contamination of the metal with coarse nonmetallic particles, and the occurrence of local overheating in the channel influence the operating life of the channel and the feeder in general. The rate of crust formation is determined by the quality of the lining fluorophlogopite material. The presence of cracks, shrinkage porosity, and an increased quantity of free glassy substance causes acceleration of failure of the channel lining.Translated from Ogneupory, No. 3, pp. 49–52, March, 1988.     

Production and performance of dense corundum refractories

Conclusions The production technology was developed and production was launched of dense superduty corundum refractories with mullite—corundum binder. The products proved to be highly durable in the lining of a channel type induction furnace at the Volga Automobile Plant.The refractories are used also for the masonry of the roof of the high-temperature glass furnaces used in the production of glass fiber and are suitable as lining material for in-vacuo steel refining installations and other high-temperature heat-using equipment.Deceased.Translated from Ogneupory, No. 7, pp. 17–18, July, 1978.     

Designing a band for a detachable unit of an induction channel furnace

Conclusions The calculations carried out indicate that a metal cylinder applied with a tolerance to the lining of the longitudinal channel creates stresses that are inverse in sign to the tensile forces at the danger site of the lining. This excludes the development of tensile forces in the danger zone of the lining, both during short-term heating and during prolonged service, i.e., it eliminates one of the main causes of cracking in the lining of the longitudinal channel of a detachable unit.During the development of microcracks in the lining, when the induction furnace is working, the band, tightening the lining, prevents microcracking. Moreover, the metal cylinder prevents penetration of melt into the heat-insulating layer through the pores of the lining, especially during vacuum melting.Translated from Ogneupory, No. 6, pp. 14–16, June, 1992.     

Experience in using zirconia refractories in linings of furnaces for the production of amorphous alloys

The structure of a two-layer lining of a melting chamber with a functional zirconia-based layer and a nonfunctional periclase layer is described. The lining has been tested in service and installed in Sirius industrial installations. It proved to have high endurance in service and ensured reliable operation of an induction furnace and the requisite purity of amorphous alloys.Translated from Ogneupory, No. 7, pp. 29 – 31, July, 1995.