Study of carbon-containing refractories for steel smelting production units

Carbon-containing refractories exhibiting different or similar resistance in steel smelting production units are studied. Properties are analyzed for articles of domestic and overseas production under conditions of a single metallurgical plant. The greatest resistance is demonstrated by articles containing a liquid binder with a significant amount of coke residue, a greater amount of fine fractions of a mineral filler, and additions of finely dispersed carbon. The substance and grain size composition and production technology form an article structure with a specific pore distribution with respect to size. The amount of pores smaller than 45 μm and an increase in their content govern an increase in refractory resistance. __________ Translated from Novye Ogneupory, No. 10, pp. 22–26, October 2007.     

含炭耐火材料中Si与SiC抑制碳氧化的机理

本文报导了含炭耐火材料氧化过程中Ｓｉ、ＳｉＣ所发生的氧化还原反应。脱碳层中Ｓｉ和ＳｉＣ所发生的氧化还原反应对含炭耐火材料的抗氧化性起着重要作用。文中解释了在反应ＳｉＣ＋２ＣＯ→ＳｉＯ２十３Ｃ不能进行热力学温度内，ＳｉＣ仍能对含炭耐火材料中碳的氧化有抑制作用的原因．从而进一步阐明了Ｓｉ和ＳｉＣ通过ＳｉＣ气相扩散到脱碳层，再氧化生成ＳｉＯ２，沉积在气孔壁上，堵塞气孔的抗氧化机理．     

含碳耐火材料的防氧化方法

结合含碳耐火材料的抗氧化要求,对添加抗氧化剂技术、表面浸渍抑制氧化法与抗氧化涂层技术及其作用机理进行了综合介绍,并在此基础上对含碳耐火材料防氧化技术的研究方向提出了一些见解。     

含炭耐火材料抗氧化涂料的配制及抗氧化原理

含炭耐火材料在高温下易被氧化,从而造成材料性能急剧下降.靠浸渍溶液或在基质中添加抗氧化剂已不能满足工业发展及某些特殊场合的要求.文章通过对多种氧化物及非氧化物原料的特点进行分析,探讨了研制的自愈合系列高温抗氧化涂料(RefractoryAnti-OxidationCoating,RAOC)的抗氧化机理.     

Fireclay refractories for service in reducing conditions

Conclusions The Chasov-Yar Refractories Combine has organized the production of firebrick of 57 standard sizes for lining the shafts of furnaces used for direct reduction of iron oxides.Tests of brick with an open porosity of up to 16% and up to 1.5% Fe₂O₃ showed that they are resistant to reducing conditions in a current of CO at 500°C for 500 h. These refractories have been in use since 1983 at OÉMK in the linings of shaft furnaces used for reduction firing of nodules. During service the working layer of the refractories becomes saturated with fine dust from the nodules, become densified and worn due to abrasion. The pores of the refractory are saturated with a small amount of finely dispersed carbon.A TU 14-8-606-90 standard specification is being prepared — Refractory fireclay shapes for constructing shaft furnaces used for nodule metallization. The bricks will be designated ShPSh-41.Translated from Ogneupory, No. 5, pp. 33–34, May, 1991.     

钢液对连铸用含碳耐火材料的侵蚀作用研究

采用中频炉的实验室模拟试验(试验条件:钢液温度1600℃,浸入时间30min,气氛分别为空气和真空)和通过对用后耐火材料的显微结构分析,研究了钢液对3种连铸用含碳耐火材料(Al2O3-C、MgO-C和ZrO2-C)的侵蚀作用。结果表明,脱碳层的形成及钢液中夹杂物与脱碳层中耐火氧化物的反应是材料蚀损的主要原因。因此,在含碳耐火材料接触钢液的表面形成致密耐火层,能有效抑制钢液对连铸用含碳耐火材料的侵蚀。     

Production of lightweight refractories from semidry bodies

Summary In the manufacture of lightweight by the semidry pressing method using thermoanthracite as the combustible addition, it is possible to obtain goods corresponding to GOST 5040-58. The firing time is 144 h. The firing should be carried out in an oxidizing atmosphere with a ten-course setting in separate chambers with a special schedule. It is necessary to carry out further work to find whether it is possible to reduce the firing time in the low-temperature interval by selecting the appropriate draft schedule.     

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.     

Rice husks as a combustible addition for making lightweight refractories

Conclusions Rice husks are an effective combustible additive for making lightweight refractories. The first products obtained in Soviet industry using rice husks were BL-1.0 and BL-1.3 lightweights corresponding to GOST 5040-58. It is of interest to consider making industrial products from clays and ash. Although the bulk density is somewhat higher than that specified by GOST for BL-1.3 goods, in their heat conductivity they correspond to class BL-1.0. The compressive strength is 220 kg/cm², the RUL is 1320°C. This makes them effective for lining heating units.     

Microstructures and properties of microporous mullite-corundum aggregates for lightweight refractories

Five microporous mullite-corundum refractory aggregates were prepared from Al(OH)₃ and kaolinite gangue through in situ decomposition synthesis technique. The effects of the sintering temperature (1400–1600°C) and the particle sizes of raw materials (20.6–94.5 μm) on the microstructures and strengths of the aggregates were investigated through X-ray diffractometer, scanning electron microscopy, and energy-dispersive spectrometer etc., to find out the technological conditions to be controlled in industrial production. The higher sintering temperature promoted the reaction between Al(OH)₃ and kaolinite gangue, leading to the development of primary-mullite as well as the generation of secondary-mullite, which promoted the formation of the neck and improved the strength. Meanwhile, the dense mullite layers were formed continuously on the surface of Al(OH)₃ pseudomorphs, making the micropores inside the pseudomorphs become closed pores, which increased the closed porosity of the aggregates. The reduction of the particle sizes of raw materials changed the particle packing behavior, accelerated the rearrangement of the Al(OH)₃ pseudomorph particles during the process of reactive sintering, and then reduced the closed porosity. To realize the industrial production of microporous mullite-corundum refractory aggregate with high strength (103 MPa) and high closed porosity (16.1%), the sintering temperature should be at about 1600°C, and the median diameter of raw materials should be at 94.5 μm.