On the problem of heat resistance of chamotte refractories

Results of a study of the heat resistance of chamotte refractories as a function of the composition of their binder are presented. The introduction of a refractory particolored clay or clay DN2 rich with alkaline and alkaline-earth oxides into chamotte-kaolin mixtures hampers the formation of cristobalite. The cristobalite effect and the temperature coefficient of linear expansion of the specimens decreases up to a temperature of 600°C, which enhances their heat resistance     

A study of the slag-induced wear of the refarctories made from magnesia-spinellid bodies with an argillaceous binder

Conclusions Among the experimental additives introduced into the composition of the magnesia-spinellid bodies, the highest resistance to the synthetic slag is exhibited by the fused and the sintered spinels and electrocorundum, and the least resistance is shown by the tricalcium and dicalcium silicates. Forsterite is the most stable silica-bearing phase.The plasticizer additions (refractory clays or bentonite) that ensure satisfactory shaping properties of the bodies are found to have an adverse effect on the slag-resistance of the systems: the interaction period required for the initiation of erosive wear decreases with increasing plasticizer content. The bentonite content in the body must not exceed 3% and the refractory clay content must not exceed 5–6%.A direct correlation with a correlation coefficient of 0.94–0.99 was established between the amount of the direct bonds existing in the refractory and the interaction period up to the initiation of erosive wear; this fact indicates the significant effect of the refractory structure and the phase distribution on the erosive wear. When the refractory clay amounts to 7–10%, erosive wear is observed within the very initial stage of interaction.Under the action of the molten synthetic slag, one does not observe much difference in the destruction of the systems containing the Latnensk and the Novoraisk clays; on the other hand, the systems containing the Latnensk clay possess a high resistance to the molten mixture of the synthetic and the converter slags. The mixture of the synthetic and the converter slags has a significant destructive action.We showed that it is advisable to introduce fused spinel and electrocorundum additives into the composition of the magnesia-spinellid based ramming bodies.Translated from Ogneupory, No. 1, pp. 5–9, January, 1986.     

Influence of Silicon Oxynitride on Slag Resistance of Al_2O_3-Si C-C Refractory

Silicon oxynitride was added in shaped Al_2O_3-SiC-C refractory material to improve the slag resistance in this paper.Optimum adding quantity of silicon oxynitride powder was also studied. The results show that the slag resistance of Al_2O_3-SiC-C shaped refractory is improved when 2% or 3% Si_2N_2O is added. A reasonable amount of Si_2N_2O added into Al_2O_3-Si C-C shaped refractory can produce silicon oxide into the slag, which can improve the viscosity of slag and prevent the slag erosion and penetration.     

CARBORUNDUM BRICK1

A study of carborundum-clay mixtures with reference to the relation between the proportioning and sizing of the constituents and the properties of the refractory as expressed by the tensile strength, the load test, the slagging and the spalling tests. For good working conditions the amount of clay must suffice to cover the grains of SiC. When subjected to crushing the linear compression varies as the second power of the percentage of carborundum. Oxidizing furnace conditions and the presence of iron oxide, lead oxide and lime reduce the resistance to slag action. The resistance to spalling depends upon the content of SiC, the tensile strength, the coefficient of expansion and the thermal conductivity of the clay. A formula is proposed for the estimation of the life of the carborundum refractories, and a theoretical explanation of their physical properties is offered.     

A comparative study on the slag resistance of dense corundum-spinel refractory and lightweight corundum-spinel refractory with density gradient

Lightweight corundum-spinel refractory with a density gradient structure from exterior to interior was fabricated. Slag resistance of lightweight and dense corundum-spinel refractory is investigated by X-ray diffraction, scanning electron microscopy, energy dispersive analysis, mercury intrusion porosimetry and Factsage. The results show that lightweight corundum-spinel refractory with high apparent porosity exhibits comparable slag resistance to dense corundum-spinel refractory, especially with superior slag penetration resistance. The dense exterior with small pore size in the lightweight corundum-spinel refractory can effectively hinder slag penetration. Corrosion product phases (C₂S, CA₂, CA₆, and C₂M₂A₁₄) with high melting point and inconsistent melting temperature, most of Fe and Mn elements in steel slag solubilizing in spinel, especially strip CA₆ around corundum aggregate, prevent the refractory from further slag penetration and corrosion.     

Slag conditioning effects on MgO–C refractory corrosion performance

Slag conditioning practice provides important benefits to the steelmaking processes including ladle refractory life improvement, lower flux cost/additions, better control of metal recovery, among others. Furthermore, with the advent of thermodynamic and mass balance calculations it is possible to predict the slag saturation and define the most suitable conditioner (oxide components) that should be added during the operational process. Thus, the aim of this work was to analyze the interaction of industrial slags and a MgO–C refractory composition by thermodynamic simulations (FactSage^™). Based on the attained results, a conditioned slag was designed and corrosion tests in the laboratory were carried out (cup-tests and induction furnace), for two MgO–C materials containing distinct magnesia sources. According to the calculated slag penetration area and refractory corrosion rate, a remarkable enhancement of the MgO–C bricks wear resistance was observed when such materials were placed in contact with the conditioned molten slag. Therefore, proper slag engineering can be a suitable replacement for purchased synthetic slags and the conditioning practices can directly improve refractory life, with more competitive costs for both, refractory producers and end-users.     

Al2O3-ZrN-Sialon-C复相耐火材料抗渣侵性能研究

以板状刚玉、石墨、α-Al2O3、金属铝粉、单质硅粉为主要原料,ZrN-Sialon复相粉体为添加剂,采用酚醛树脂结合制备了Al2O3-ZrN-Sialon-C复相耐火材料.采用静态坩埚法研究了ZrN-Sialon复相粉体加入量对材料抗渣侵蚀性能的影响,借助SEM与EDS面扫描对渣蚀后材料的结构和成份进行分析,并探讨了Al2O3-ZrN-Sialon-C复相耐火材料的抗渣侵蚀机理.结果表明:ZrN-Sialon复相粉体加入量为9wt％时,材料表现突出的抗钢渣侵蚀性能.研究表明材料中Sialon氧化后生成的SiO2能形成致密的氧化保护层,同时ZrN氧化后形成的ZrO2有利于提高抗钢渣的浸润,阻止钢渣的渗透与侵蚀.分析认为Al2O3-ZrN-Sialon-C复相耐火材料的钢渣侵蚀机理为氧化-熔蚀-渗透.     

Slag resistance of periclase-carbon refractories based on modified phenol formaldehyde resin

Results are provided for a study of the slag resistance of periclase-carbon specimens based on modified phenol formaldehyde resin using different forms of filler, i.e., sintered and fuzed periclase. It is established that penetration of molten slag and its reaction with refractory is independent of the form of periclase filler. There is a reduction in slag penetration into refractory with introduction of modifying additions.     

Methods of determining the corrosion resistance of glass-tank refractories

Conclusions When laboratory investigations are being carried out to find resistant refractories for glass tank furnaces it is desirable to make simultaneous use of indirect and direct methods of assessing corrosion resistance.The use of indirect methods for determining corrosion resistance in refractories permits us to explain the nature of the interaction between the refractory and glass, to study the nature and properties of the reaction products, and also to select refractories that form with the glass the most infusible or viscous reaction products for subsequent investigation in molten glass.The direct methods permit direct determination of the rate of corrosion of refractories by glass at working temperatures and allow us to recommend the most corrosion resistant refractories for tests in service conditions.In laboratory conditions we established that the most corrosion resistant refractories in regard to original glass used for obtaining slag sitalls are bakor-33 and dense zirconium refractory. This may be explained by the formation of viscous reaction products in the contact layer which have a protective action on the refractory.Translated from Ogneupory, No. 5, pp. 56–60, May, 1967.     

Experience in pressing standard brick from clays and kaolins in thermoplastic state

Conclusions The pressing of argillaceous raw material reduced to a thermoplastic state by heating produces ultradense refractory of high quality.Standard brick made of 50% Vladimirovka kaolin, 3-1 mm, and 50% Chasov-Yar clay finer than 0.5 mm, pressed to 100 kg/cm² and at about 1380°, containing 40% Al₂O₃, shows a high degree of slag resistance and spalling resistance, and has an apparent porosity of 3% bulk density 2.52 g/cm³.     

Cladding and corrosion characteristics of magnesium-aluminum spinel refractory by alkaline slag during alkali recovery

The alkaline slag produced during alkali recovery might cause harm to the furnace's refractory components. The seat-drop technique and static dry pan method are used to explore the cladding features and corrosion characteristics of alkaline slag on the surface of magnesia-alumina spinel refractory in this paper. SEM-EDS and XRD are used to study the microstructure, fundamental changes, and compound composition of the molten cladding and interfacial layers, as well as the trends of slag column alterations. Factsage 7.2 software is used to model the interaction between the molten slag and the refractory. The results demonstrate that the wettability process of the slag column is impeded in a reducing environment. Combine with the results of the thermodynamic simulate, it is found that the formation and transformation of a large number of high melting point compounds in a reducing atmosphere is the decisive reason for the inhibition of wettability. Temperature increases promote the production of high melting points substances such as magnesium silicate and sodium metal aluminate, which alters the micro-morphology of the materials and improves slag resistance and permeability resistance of refractories.     

Slag and hot-slag resistance of basic refractories

Conclusions Using the instrument described, which has been improved in design for testing refractory materials for slag and hot slag resistance, we investigated the properties of magnesite, magnesite-chromite, and chrome-magnesite specimens. It was established that their life is determined by the resistance of the refractory bond. The best resistance is possessed by periclase-spinel specimens. An increase in the content of calcium oxide in the slags reduces the slag resistance of all periclase-spinel refractories that were tested. Impregnating the magnesite products with a saturated solution of chromium acetate and firing them after impregnation at 400–500°C markedly increases their slag resistance.Translated from Ogneupory, No. 7, pp. 47–52, July, 1968.     

高炉矿渣对玻璃熔窑用耐火材料的侵蚀研究

利用冶金固废(矿渣)制备玻璃产品成为近年来行业关注的热点,研究矿渣对耐火材料的侵蚀情况有助于选用合适的耐火材料作为熔窑的主体,延长熔窑寿命,减小生产成本。本文以某钢厂的高炉矿渣作为原料,对玻璃熔窑常用的几种耐火材料(α-β电熔刚玉砖,1195致密锆砖,41~#电熔砖和33~#电熔砖)进行了侵蚀实验。通过1 450℃保温12 h、24 h、48 h对比实验,结果表明,α-β刚玉砖和1195致密锆砖耐矿渣侵蚀能力明显优于41~#电熔砖和33~#电熔砖,气孔率低的耐火材料更耐侵蚀。     

浅析影响耐火制品抗渣性的因素

简要阐述了熔渣侵蚀耐火材料的侵蚀机理和侵蚀方式，详细分析了影响耐火材料抗渣性的几个因素，进而提出了在生产工艺中提高耐火制品抗渣性的途径。     

Influence of the aluminum oxide content of chamotte gunite masses on their slag resistance

Conclusions The authors investigate the influence of the aluminum oxide content of chamotte gunite masses on their slag resistance in contact with converter and synthetic slags. The refractory undergoes wear by dissolution of its surface in the fused slag; the slag does not penetrate very deeply into the refractory.A significant increase in slag resistance is observed only when the aluminum oxide content of the slag is 40% or more. An increase in the aluminum oxide content from 34–35 to 37–39% is not accompanied by a marked increase in the slag resistance. Linear regression equations with high correlation coefficients (0.70–0.98 in absolute value) have been constructed for different aluminum oxide content ranges.A more significant decrease in slag corrosion can be attained by introducing special additives into the chamotte mass composition.Translated from Ogneupory, No. 6, pp. 30–32, June, 1980.     

Experience with the use of Latnensk siliceous fireclays

Conclusions Using semiacid Latnensk clay LT1PK and LT2PK it is possible to produce refractories meeting the requirements of GOST 4873–49. The articles were distinguished by excellent slag resistance, and satisfactory thermal-shock resistance, and can be used by the consumer together with firebrick, for those applications including conditions of molten metal and slag action.The production technology developed by the All-Union Institute and the Novomoskov Firebrick Factory for semiacid products specifies the firing of semiacid clay LT2PK in a rotary kiln, and semidry pressing of the articles from bodies containing average quantities of nonplastics.Translated from Ogneupory, No. 3, pp. 10–15, March, 1972.     

Slag resistance of vibration-cast refractory concretes with an aluminosiliceous composition

The slag resistance of refractory concretes prepared from mechanically activated aluminosiliceous binding suspensions is investigated. The composition of the binding part of vibration-cast refractory mixtures strongly affects their slag resistance. A good effect is obtained by introducing finely milled corundum-, zircon- and chromium-containing additives. The concretes were tested in the lining of a heating well and in the lining of the doors of the charging gates of open-hearth furnaces.Translated from Ogneupory, No. 2, pp. 28 – 30, February, 1996.     

A basic gunning material interfaces study

Corrosion mechanisms of various basic gunning materials were investigated using crucible tests. The low corrosion resistance of olivine-containing materials was shown to be related to melted phases formation which occurs, at the gunning material/slag interface, at high temperature. MgO-rich materials are more resistant to basic slag attack. Moreover, increasing the refractory material CaO content by means of dolomite addition rises the slag penetration resistance and lowers the bulk modification resulting from slag interaction. In these materials, the corrosion mechanism involves a slag reaction with the starting binder, (NaPO₃)_n, and dolomite initially contained in the gunning material. A dolomite-containing material was projected on slag-covered MgO-C bricks, using a laboratory test equipment. Investigations carried out at the gunned material/slag/bricks interface show that the suitable silicophosphate bond still forms, at interface, despite slag interaction.     

基于数字图像相关法的铝镁质耐火材料抗侵蚀性能研究

钢渣侵蚀是耐火材料在服役过程中的主要损毁形式之一,实际侵蚀过程难以直接观察。传统上采用蚀后分析方法来评价耐火材料的抗侵蚀能力和了解侵蚀机理,但易缺少过程信息,导致结果存在偏差。因此,本文在高温可视化系统基础上,结合数字图像相关法,选取三种典型钢渣,开展铝镁质耐火材料的渣蚀行为研究,并探讨了不同钢渣及热处理温度对材料抗侵蚀能力的影响。结果表明：碱度越低的熔渣对铝镁质耐火材料的侵蚀越严重;对铝镁质耐火材料进行1 000℃以上的热处理,可有效提高材料的抗侵蚀能力;通过数字图像相关法可以获得随时间变化的平均应变曲线和侵蚀应变云图,其中平均应变曲线可以对比铝镁质耐火材料对不同钢渣的抗侵蚀能力,侵蚀应变云图可以反映侵蚀的演变过程,两者为耐火材料渣蚀过程的表征提供了量化指标。     

Improvement of low carbon MgO-C refractories by MA-CA2 additives fabricated from metallurgical waste

In the present work, MA-CA₂ material was fabricated by adding industrial alumina into industrial waste residue, and its effect on the physical properties, oxidation resistance, slag resistance, and thermal shock resistance when it was added to the composition of a low carbon MgO-C refractory was discussed in detail. Although the introduction of MA-CA₂ material led to a slight inferior slag corrosion resistance, the volume stability and oxidation resistance of refractories were improved. Moreover, the samples containing MA-CA₂ addition showed significantly lower thermal expansion coefficients and increased thermal shock resistance performance. However, owing to the dissolution of SiO₂ impurity into the MA-CA₂ material, an excessive addition of MA-CA₂ material would increase the liquid phase amount in the sample during the heat treatment and slag attack, resulting in a performance degradation. In this study, the best comprehensive performance of the MgO-C refractory was obtained with 6 wt% MA-CA₂ addition.