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     

抗渣性耐火材料的研究进展

主要从耐火材料的侵蚀机理出发简单叙述了改善耐火材料抗渣性的几种方法;通过几种典型的耐火材料总结了研究者们在耐火材料抗渣性提高方面所做的工作。     

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.     

不同条件下白云石耐火材料抗侵蚀性的研究

采用真空感应炉法与静态坩埚法,分别研究了烧成白云石耐火材料在碱度为0.6、1.1、1.5和1.8的CaO-SiO2渣与Al2O3含量为37.98%的CaO-Al2O3渣中的抗侵蚀性。真空感应炉浸棒法的试验条件是真空度5kPa、1650℃保温25min;静态坩埚法的试验条件为空气气氛下于1650℃保温60min。对侵蚀后的试样进行观察与测量,并用SEM与EDAX分析了试样的断面形貌和化学组成变化。结果表明,在静态坩埚法抗渣试验条件下,在CaO-SiO2渣中,随着熔渣碱度的升高,试样与熔渣生成高熔点的C2S保护层,阻挡了熔渣的侵蚀,表现出较好的抗侵蚀性。在真空感应炉浸渍试样的试验中,在CaO-SiO2渣中,随着熔渣碱度的升高,试样抗侵蚀性呈现出先增强后减弱的趋势;在CaO-Al2O3渣中,试样侵蚀后形成低熔点的C12A7,试样的抗侵蚀性很差。     

电站锅炉用SiC质耐火材料抗渣性的研究

以SiC粉和Al2O3粉为主要原料,分别添加5%(质量分数,下同)的ZrO2粉或锆英石粉和5%、10%的Cr2O3粉以及4%的羧甲基纤维素(CMC),按照配料组成配料后,以成型压力为20 MPa制成40 mm×40 mm×30 mm的试样.试样经120℃干燥8 h后,置于硅钼棒炉中.于1 420 ℃保温5 h烧成后,分别采用经900℃保温2 h处理后的粉煤灰在1 400和1 450 ℃下进行抗侵蚀试验.结果表明:SiC质材料随着温度的升高,抵抗灰渣侵蚀能力不断下降,在1 400 ℃时的抗渣性明显优于1 450 ℃时的;在SiC质材料中分别加入5%的ZrO2或锆英石,前者的抗渣性能强于后者;含Cr2O3为10%的SiC质材料比含5%Cr2O3的具有更好的抗渣性.     

Reaction between zinc oxide and chamotte refractories

Conclusions As a result of chemical reaction between chamotte and zinc oxide, zinc aluminate ZnAl₂O₄ and zinc silicate Zn₂SiO₄ are formed.The mullite is not chemically resistant under the action of zinc oxide. Even at 900°C mullite reacts with zinc oxide, forming ZnAl₂O₄ and SiO₂.In accordance with the quantity of melt formed in the refractory under the action of zinc oxide, high-alumina products should be more resistant to the action of vapors and oxides of zinc at elevated temperatures than chamotte and semiacid refractories.Translated from Ogneupory, No. 7, pp. 36–39, July, 1971.     

微孔刚玉和板状刚玉耐火材料的抗渣性对比

分别以微孔刚玉和板状刚玉为原料,按粒度为3～1、≤1和≤0.088 mm的原料质量分数分别为35%、30%和35%配料,外加4%的纸浆废液作结合剂,压制成坩埚试样,在1 600℃保温3 h烧成后,加入10 g碱度为3.2的转炉终渣,在1 600℃保温3 h条件下进行抗渣试验,然后测量并计算试样的侵蚀指数和渗透指数,并对侵蚀后试样进行了形貌观察、元素面分布分析和微区成分分析.结果表明:两种刚玉质耐火材料的抗渣侵蚀性基本相同,但是,以微孔刚玉制备的试样的抗渣渗透性却比以板状刚玉制备的差.     

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.     

镁铬耐火材料在真空条件下的抗渣性

采用真空感应炉抗渣法,研究了半再结合镁铬耐火材料在碱度分别为0.6、1.1、1.5和1.8的CaO-SiO2渣与Al2O3含量为37.98%的CaO-Al2O3渣中的抗侵蚀性,试验条件是真空度5kPa、1650℃保温25min。对侵蚀后的试样进行观察与测量,并用SEM与EDAX分析了试样的断面形貌和化学组成变化。结果发现:在CaO-SiO2渣中,随着炉渣碱度的升高,镁铬试样中的尖晶石更易于受到熔渣的侵蚀,并且尖晶石中的Cr2O3、Fe2O3被CO与钢水中的C还原为金属态的铬铁合金,试样的直接结合被破坏,侵蚀量变大。在CaO-Al2O3渣中,镁铬试样在边界层生成致密的MA尖晶石,抑制了熔渣的进一步侵蚀和Cr2O3、Fe2O3的还原,显示出较好的抗侵蚀性。     

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.     

Berlin clay as binder for chamotte products

Conclusions A. technology was developed and introduced for the production of ladle and steelcasting refractories bonded with a mixture of 75% Berlin clay and 25% Arkalyk clay.The durability of the ladle lining was 1.5 melts higher when constructed of this brick.Translated from Ogneupory, No. 7, pp. 4–6, July, 1977.     

Systems analysis of the technology for unfired lightweight chamotte refractories

General principles of systems analysis of self-compaction technology are considered. A group of factors responsible for functioning of individual blocks and the process as a whole is established. Analytical dependences relating the characteristic factors of the manufacturing process are derived by methods of statistical analysis and interpreted graphically. The results of the study are used to solve practical problems of choosing raw materials for refractory compositions and the process regimes. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 4, pp. 2–7, April, 1998.     

Improving the quality of chamotte made from Berlinsk clay

Conclusions The optimum firing temperature for Berlinsk clay to convert it into chamotte is 1300–1330°C. Above this temperature the chamotte bloats and has a low apparent density (below 2.10 g/cm³). The fireclay goods should be made from chamotte with an average or high apparent density (2.14–2.30 g/cm³).The articles made with the overtired chamotte have a high porosity and low apparent density. It is not recommended for use in firebrick production.Translated from Ogneupory, No. 2, pp. 14–16, February, 1981.