Life of refractories in the lining of a cyclone reactor

Conclusions Tests of refractories in the linings of cyclone reactors for the production of industrial carbon showed that mullite-corundum, corundum, and zirconium-containing refractories, which are recommended for wide use, possess the longest life. Alumina-silicon carbide, kaolin-base chamotte, chamotte-graphite, and silicon carbide parts fail rapidly in the reactor linings and are not suitable for these service conditions. Disthene-sillimanite and kaolin-base chamotte (with a mullite-corundum binder) parts showed satisfactory results in service and occupy an intermediate place in life between the first and second groups of refractories.Translated from Ogneupory, No. 2, pp. 46–50, February, 1985.     

Resistance of silicon carbide referactories to the effect of aluminum melt and aluminum chloride vapor

Silicon carbide refractories with binders of silicon nitride and silicon oxynitride are compared with dense aluminum silicate refractories. It is shown that silicon carbide refractories possess high stability in aluminum melts and vapors of aluminum chloride, whereas aluminosilicate refractories are severely damaged under these conditions. Silicon carbide refractories with a binder of silicon nitride possess the highest resistance to the effect of the tested aggressive factors and are recommended for operation in aluminum melts and gaseous aluminum chloride media.Translated from Ogneupory, No. 12, pp. 2–5, December, 1995.     

An investigation of different forms of refractories for the service conditions in coke ovens

Conclusions Investigations of different forms of refractories established that it is desirable to use refractory parts with high heat resistance (MK-80 mullite-corundum, silicon carbide, chamotte-cordierite) as extreme roof and hearth parts in place of chamotte ones for increasing the life and providing reliability in service of these elements of the coke oven lining. The most promising for these purposes from the economic point of view and taking into consideration high heat resistance, resistance to reduction, and minimum thermal expansion are chamotte-cordierite parts.Translated from Ogneupory, No. 2, pp. 36–37, February, 1991.     

Future application of aluminosilicate refractories for aluminum electrolyzers. Part 4. Wettability of aluminosilicate refractories with molten industrial electrolyte and sodium fluoride

Optical microscopy is used to determine wetting angles for aluminosilicate refractories with molten industrial electrolyte and NaF. Kinetic wetting parameters and interaction of electrolyte with refractory are determined. It is shown that removal of silicon from refractory also occurs in the form of silicon monoxide. It is established that aluminosilicate refractories, prepared with addition of mullite-corundum chamotte, are wetted worse by fluoride salts, but the corrosion resistance of them is better than for refractories prepared by normal technology. __________ Translated from Novye Ogneupory, No. 1, pp. 17–21, January 2008.     

Silicon carbide refractories with a sialon binder

An investigation concerning molding of silicon carbide refractories with a sialon binder was carried out. It is shown that the alumina-containing component plays an important role in the synthesis of the sialon binder. A corundum addition to the composition of silicon carbide refractories ensures higher parameters for the refractory as compared to a mullite addition. With an increase in the content of crystalline silicon the strength of silicon carbide refractories grows sharply due to the increased amount of -sidalon. Refractories with elevated contents of sialon in the binder have better resistances to alkali, slag, and molten metal than refractories with binders containing silicon nitride.Translated from Ogneupory, No. 4, pp. 2–4, April, 1995.     

Sialon-containing silicon carbide refractories

Conclusions We worked out the technology of sialon-containing silicon carbide refractories for lining the shafts of blast furnaces. It was shown that addition of MgO in combination with the waste products of the oxides of the rare-earth elements improves the strength and the other properties of the products fired at 1550°C in nitrogen atmosphere.The sialon-containing silicon carbide refractories exhibit a high resistance to the action of slags and are recommended for lining the lower portion of the shaft and the bosh of blast furnaces.Translated from Ogneupory, No. 5, pp. 6–8, May, 1992.     

Advanced Refractory Products and Materials Developed at the A. S. Berezhnoi Ukrainian Research Institute for Refractories Joint-Stock Co.

A brief survey of R&D activities carried out at the A. S. Berezhnoi Ukrainian Research Institute for Refractories (UkrRIR) Joint-Stock Co. is presented aimed at the output of unique high-tech refractory products for metallurgical, machine building, glass-making, petrochemical, and other branches of industry. A wide range of products recently developed and/or commercially available is considered: refractory components of different size and shape — mullite-corundum, corundum with zircon added, chromium oxide, periclase-lime-carbon, silicon carbide, zirconia, high-efficient lightweight calcium hexaaluminate and anorthite-based composites, concrete and ramming mixes of corundum zirconia, mullite-corundum, mullite-silica, chamotte and silicon carbide composition (low-cement included).     

Corrosion of oxide bonded silicon carbide refractories by molten salts in solid waste-to-energy facilities

Oxide bonded silicon carbide refractories are used successfully in solid waste-to-energy facilities (WtE). They are submitted to severe thermo-chemical stresses that limit their performance. Even if the corrosion resistance of silicon carbide is high, wear and failure of refractory lining are currently observed.For a better understanding of corrosion mechanisms, oxide bonded silicon carbide refractories, collected in the combustion chamber of several WtE facilities, were examined. The main mechanisms of corrosion, according to the environment of refractories, were determined. The chemical composition and the nature of the corrosive agents were calculated from the thermo-chemical modeling. They are mainly condensed phases of sulfates and chlorides (CaSO₄, K₂SO₄, Na₂SO₄, KCl, and NaCl). In service conditions, these molten salts react with the SiC aggregates and the matrix of the refractories to form low melting compounds.The post-mortem analyses showed the formation of para-wollastonite in the porosity and around the SiC grains, on the hot face of refractory tiles. Other phases such as cristobalite and microline (KAlSiO₈) were also formed down to the core of refractories. The volume expansion created by the formation of new mineral phases (cristobalite, para-wollastonite) causes the formation of micro cracks in the refractory lining.In this paper, the degradation mechanisms of oxide bonded silicon carbide refractories are presented and the main research developments for the future are discussed.     

氮化物结合碳化硅耐火材料的研究进展

对氮化物结合碳化硅结合耐火材料的研究现状进行了综合评述，认为氮化硅或赛隆结合的碳化硅在性能上更适宜于高炉内应用；氧化法烧成的含氮化物结合产品性能还需要进一步改进。     

Mullite-alumina refractories with combined nitride-containing binders

Formation of a combined nitride-containing binder for mullite-alumina refractories is studied. An optimal combination is found to consist of 80% crystalline silicon, 10% silicon carbide, and 10% aluminum, magnium, or zirconium oxide. Mullite-alumina refractories with selected binders showed high resistance to the effects of slag, alkali, and iron.Translated from Ogneupory, No. 6, pp. 9–13, June, 1994.     

Determining the resistance of refractories in a slag stream

Conclusions A method is proposed for testing refractories for slag resistance at 1500–1600°C. The results of investigation into high-grade refractories showed that their resistance is variable, and in the main is extremely low. Only silicon carbide, nitride-bonded silicon carbide, and carbon specimens will resist convective slag at 1500–1550°C. The other refractories were destroyed in varying degrees by the slag.Destruction of oxide refractories with an increase in the basicity of the slag is markedly increased, In these conditions nonoxide materials have about the same degree of destruction.Translated from Ogneupory, No. 8, pp. 53–58, August, 1967.     

Sialon结合SiC耐火材料的化学稳定性

采用高岭土、炭黑为主要结合相原料,合成了Sialon结合SiC耐火材料。考察了Sialon结合SiC耐火材料的氧化行为、高温碱侵蚀行为和冰晶石熔体的侵蚀行为。结果显示,合成Sialon结合SiC耐火材料具有高的机械强度和化学稳定性。     

Industrial development of vibroimpact molding of silicon carbide refractories

Conclusions A technology was developed for the vibrocompaction of silicon carbide refractories. The efficiency of the process was confirmed in industrial conditions.The properties achieved by vibrocompaction in silicon carbide refractories and their uniformity of distribution appreciably exceeds similar characteristics for tamped, and to some extent pressed, refractories.Vibromolding equipment is very simple in design, of low metal content, low power rating and cost, and can be used to obtain product qualities at pressures of 1–2 kg/cm² that are achieved in pressing only by pressures of about 1500 kg/cm².The use of vibrocompacted silicon carbide slabs in the porcelain industry as kiln furniture increased the inter-repair periods for shelf cars for firing pottery.Translated from Ogneupory, No. 8, pp. 7–12, August, 1970.     

Silicon carbide refractories in the lining of the cooler drum

Conclusions Tests were carried out at the Magnezit Combine with silicon carbide refractories in the lining sections subjected to maximum wear in the 36-m-long drum for the cooling of fired magnesite powder. The durability of the experimental bricks was 3–4 times greater than that of chamotte bricks.It was established that silicon carbide scrap and spoilage material are suitable for the production of high-durability refractories for service in a lining subjected to severe abrasion.Translated from Ogneupory, No. 5, pp. 28–30, May, 1978.     

Silicon carbide articles for linings of reactors for the production of aluminum chloride

The technological parameters of the production of silicon carbide refractories with a silicon nitride binder are investigated. An experimental industrial batch of refractories has been produced by the Semiluki Refractory Plant and shipped to the Kaustic Production Association to be used in linings of reactors for the production of aluminum chloride. Translated from Ogneupory, No. 9, pp. 15 – 17, September, 1995.     

Review of corrosion of refractory in gaseous environment

Advancing high temperature technologies pushes the envelope of the service conditions to new extremes. However, corrosion of refractories substantially decreases the service life and causes unscheduled shutdown of manufacturing and processing plants. In this paper, corrosion of refractories in gaseous environments is reviewed. The corrosion mechanisms of alumina refractories, including alumino-silicates and zirconia as oxide, and silicon carbide as non-oxide refractory are emphasized due to their broad array of applications. It is shown that carbonaceous atmosphere and water vapor are detrimental for the oxide refractories. Interaction with water vapor leads to formation of the volatile species and subsequent recession of the refractories. Carbonaceous atmosphere leads to the decomposition of even mullite, which is categorized as neutral refractory due to its excellent thermochemical stability. Oxidizing atmosphere with water vapor dominates the corrosion of non-oxide refractories. Presence of impurities, even parts per million level, in the gas stream such as alkali vapor and halogens can alter the corrosion mechanisms and favor “hot corrosion.”     

Mullite corundum articles for electric furnace roofs

Conclusions Using a method developed by the Institute we produced an experimental batch of synthetic mullite-corundum refractories containing more than 72% Al₂O₃. The properties of these refractories exceed similar properties for regularly produced articles close in composition, which enables us to recommend them for use in the roofs of arc electric steel-melting furnaces.The experimental batch of synthetic mullite-corundum articles is being sent for testing in DSP-100 furnaces at the Chelyabinsk Metallurgical Combine.Translated from Ogneupory, No. 7, pp. 22–25, July, 1986.     

氮化硅结合碳化硅耐火材料在钢水中的腐蚀行为

运用扫描电镜（ＳＥＭ）技术，研究了氮化硅结合碳化硅耐火材料在钢水中的腐蚀行为。结果表明，金属与氮化硅结合碳化硅材料之间的界面清晰，基体内部无任何金属渗入，但氧化的材料表面有氧化物粘附。     

Deformation characteristics of silicon carbide and chamotte refractories

Conclusions It was established that silicon-carbide refractories with bonds of silicon nitride and oxynitride, and also self-bonded silicon carbide articles possess 2–3 times higher elasticity moduli compared with chamotte (firebrick) refractories.The anisotropy of the elasticity modulus determined in the longitudinal and transverse directions of the refractories is markedly higher (anisotropy coefficient n=2.28–2.49) than for chamotte refractories (n=1.22).In high-temperature conditions (1600–1650°C) the compressive strength of SiC refractories is about 28 N/mm², and the tensile strength 2.1 N/mm², i.e., the compressive strength is about 10 times higher than the tensile.At room temperature the strength of SiC refractories is double that of chamotte, while at 1200–1400°C this difference increases to 10 times.Silicon carbide self-bonded articles at high temperatures possess the highest strength properties, which confirms the effectiveness of using them in service under the action of abrasive forces.A new method was developed for determining the deformation and strength characteristics of refractories on the UITS-0.5/2.5 test machine.A method was developed for obtaining tension and compression diagrams from the results of tests for pure and longitudinal-transverse bending.Translated from Ogneupory, No. 7, pp. 8–13, July, 1989.     

Effect of additives on the properties of silicon carbide-based refractories obtained by self-propagating high-temperature synthesis (SHS)

The effect of refractory additives (alumina, alumosilicate mortar, and zircon concentrate) on the properties of SHS refractories based on silicon carbide is studied. It is shown that introduction of the additives favors enhancement of the compressive strength of the material. The enhancement is especially efficient in the case of an admixture of zircon concentrate. The resistance of the silicon carbide material to corrosion in slags of titanium production and iron foundry production is improved when the content of the additives is increased from 5 to 30%. The addition of zircon concentrate allows the slag-resistance of the silicon carbide material to be increased by a factor of 6, while the effect of alumina and alumosilicate mortar is less pronounced. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 1, pp. 17–18, January, 1997.