ZrO_2引入方式和引入量对MgO-ZrO_2砖性能的影响

镁铬砖一直被广泛应用于水泥回转窑烧成带和过渡带.但是,由于Cr5+对环境的污染,国外已经禁止使用含铬耐火材料,国内也在大力研究镁铬砖的替代产品[1].通过长期的摸索和试验发现,有希望替代镁铬砖的产品有镁白云石砖、镁锆砖和尖晶石砖[2].由于镁白云石砖的水化问题难以解决,镁锆砖和尖晶石砖便成为主要的研究对象.本工作主要研究了ZrO2引入方式(锆英石、单斜ZrO2、Zr(OH)4溶胶)和引入量对MgO-ZrO2砖常温物理性能的影响.     

无碱玻璃对含锆耐火材料侵蚀作用研究

介绍了旋转抗渣试验方法,研究了无碱玻璃对3种含锆耐火材料（熔铸AZS砖、致密锆英石砖和颗粒氧化锆砖）的侵蚀作用,采用该方法对试验后的试样利用SEM和EDAX对其物相组成和显微结构进行了分析。结果表明：无碱玻璃熔体的渗入及含锆耐火材料中的ZrO2的熔蚀是材料蚀损的主要原因;致密锆英石砖由于组成和结构的优化,抗无碱玻璃侵蚀性要优于另外两种砖。     

镁锆砖的抗RH炉渣侵蚀机制

为实现RH炉的无铬化,以电熔镁砂、单斜锆为原料制备了ZrO2质量分数为11%的镁锆砖,并采用回转抗渣法进行镁锆砖和电熔再结合镁铬砖的抗高、低碱度RH炉渣对比试验,并分析了其抗渣机制。结果表明:(1)镁锆砖抗高碱度渣侵蚀性能较再结合镁铬砖强,但其抗低碱度渣侵蚀性能相对较差;在高碱度渣中形成含锆酸钙反应层是镁锆砖抗渣侵蚀性能优越的关键。(2)镁锆砖中的ZrO2吸收渣中的CaO而使渣碱度降低,黏度升高,从而使渣在镁锆砖中的渗透程度降低。(3)镁锆残砖的渣层含微量的ZrO2,从工作面到原砖层,镁锆残砖呈现出明显变质层、轻微变质层和原砖层3个段带,而镁铬残砖只有明显变质层和原砖2个段带;镁锆砖的SiO2含量在轻微变质层中最高,而镁铬砖的SiO2含量从工作面到原砖层逐渐减小。     

还原冶炼时高铝石墨质耐火材料对熔体的抗侵蚀性

采用静止的方法及动力学方法研究了Al2O3-C质耐火材料在还原冶炼的熔体中的抗侵蚀性。研究了试验后试样的微观结构。查明,当向刚玉石墨质耐火材料中加入碳（以石墨形成加入）及ZrO2时其抗侵蚀性将随之降低。试验结果表明,含ZrO2的砖的抗侵蚀性高于不含ZrO2的砖。加入ZrO2时有助于提高耐火材料的抗氧化性,井使熔体和耐火材料之间的反应速度下降。Al2O3-C质耐火材料受到侵蚀的原因,一是熔体和耐火材料之间发生反应,二是耐火材料的组分在熔体中发生分解所致。     

玻璃熔窑耐火材料配套使用的现状与前景

(一)概述 近10年内我国玻璃熔窑耐火材料发展迅速,作为熔窑主体材料的含ZrO_2 33％电熔锆刚玉砖,近五年内产量翻了二番,质量亦有所提高;电熔砖新品种如含ZrO_2 36％锆刚玉砖已批量试产,氧化熔制的α-β刚玉砖已试制成功,含ZrO_2 41％锆刚玉砖正在突破中。新电熔浇注工艺的产品如池壁倾斜浇注大砖、密实浇注大砖均已投入生产。优质烧结材料如锆英石砖、含ZrO_2 8％、20％、30％的锆莫来石砖、锆英石散状料等品种,均处于试用阶段。硅砖的质量亦已引起重视。上述材料的发展与应用,为玻璃工业提高生产效益与节能提供良好的     

水泥回转窑烧成带用耐火材料的最新研究

对水泥回转窑烧成带用耐火材料的使用条件和要求进行了分析,并对近年来水泥窑用镁铬砖、镁尖晶石砖、镁钙锆砖的应用进行了探讨,指出所存在的缺点及改进措施。认为其发展方向为镁钙锆砖及尖晶石砖,并对其应用前景进行了展望,希望实现水泥回转窑的无铬化。     

水泥回转窑用无铬砖的演变

介绍了日本国内外水泥回转窑用耐火材料的演变和最近无铬砖的开发使用情况。目前无铬砖有白云石砖、镁尖晶石系无铬砖、铁尖晶石系无铬砖、镁钙锆系无铬砖等，其中Mgo—CaO-ZrO2系无铬砖具有与镁铬砖同等以上的性能。今后，无铬砖将象镁铬砖一样，可在水泥回转窑烧成带任何部位上使用。     

RH真空炉衬用无铬耐火材料抗渣性能的研究

对镁锆质、镁尖晶石质、镁尖晶石钛质和镁尖晶石锆质4种典型的无铬耐火材料的抗渣侵蚀性能进行了研究,并与RH真空炉下部槽用镁铬砖进行了对比。结果表明:炉渣对耐火材料的侵蚀主要是通过炉渣中铁氧化物、CaO、SiO2和MnO向材料内部扩散而产生的侵蚀反应造成的。镁锆质材料中的ZrO2吸收炉渣中的CaO生成高耐火性能的CaO.ZrO,使镁锆材料较其他3种MgO基无铬耐火材料具有更优良的抗炉渣侵蚀性。     

镁钙锆砖在新型干法回转窑烧成带的应用

50年代悬浮预热器和70年代预分解窑的出现,大大地提高了水泥窑的热效率和单机生产能力,促进了水泥工业大型化、现代化发展,而耐火材料随着水泥生产工艺的发展,也不断地开发出新的品种,以适应新型于法生产不断提高的要求,而其中碱性耐火材料的使用更为普遍。水泥回转窑常用的碱性砖有4种,即镁铬砖、尖晶石砖、白云石砖、镁锆砖,这4种砖在性能及使用过程中有不同的优缺点:镁铬砖有较高的抗高温性能、抗SiO2侵蚀和抗氧化还原作用,同时有较高的高温强度和抗机械能力以及较好的结窑皮性能,但是在水泥窑内使用时,在碱（或硫）的作用下,稳定的 Cr3 转化为氧化能力极强的Cr6 ,对人体的皮肤、呼吸神经、肺等造成严重危害;尖晶石砖、白云石砖、镁锆砖在水泥窑的使用中性能不断完善,但其在我国水泥工业的应     

白云石耐火材料在水泥回转窑上的应用

一、引言目前,白云石质耐火材料在水泥回转窑上的使用范围除主要用于烧结带外,已扩展到过渡带。品种以烧成白云石砖为主,包括各种普通烧成白云石砖、直接结合白云石砖、含ZrO_2白云石砖和烧成镁白云石砖等。本文主要介绍国外白云石质耐火材料在水泥回转窑上的使用效果、存在问题及今后的发展情况。     

m-ZrO2和ZrSiO4对MgO-CaO砖性能的影响

以镁钙砂、中档镁砂、高纯镁砂粉、单斜氧化锆(m-ZrO2)、锆英石等为原料,研究了ZrO2的加入形式与加入量对MgO-CaO砖性能的影响。结果表明:当ZrO2以m-ZrO2的形式加入到MgO-CaO砖中时,可以提高试样的常温性能、抗水化性、抗热震性等,m-ZrO2加入量(质量分数,下同)为2%~7%时,试样具有良好的常温性能,加入量为5%时抗水化效果较好,加入量为10%~15%时抗热震效果较好;当ZrO2以锆英石细粉的形式加入时,会明显提高试样的抗水化性及抗热震性,锆英石加入量为5%时,试样的抗水化性及抗热震性优越,但随着锆英石加入量的增加,试样的体积密度、强度明显下降,加入量大于10%以后,制品大多疏松开裂。     

活性石灰套筒窑煅烧带的材质选择

本文主要通过对几种耐火材料的热震稳定性、抗石灰侵蚀性和耐磨性能的实验和分析,以及对本钢活性石灰套筒窑煅烧带坍塌原因的分析,最终得出应该选择镁铝尖晶石材质的制品代替原来所用的纯镁质制品作为活性石灰套筒窑煅烧带的砌筑材料的结论。     

富铝尖晶石对镁质耐火材料抗侵蚀性的影响

研究了富铝尖晶石对镁质耐火材料抗钢渣与抗钙处理钢侵蚀性的影响。结果表明 :随着富铝尖晶石加入量的增加 ,镁质耐火材料的抗钙处理钢和钢渣熔蚀性逐渐减弱 ,而抗钢渣渗透性逐渐增强 ;纯镁质和镁尖晶石质耐火材料在抗钢渣与抗钙处理钢侵蚀方面远远优于铝锆碳质材料     

A Retrospective Review of Alumina-magnesia-carbon Refractories

The residual expansion of in-situ spinel formation in using of alumina-magnesia-carbon(AMC)bricks monolizes the lining of steel-making ladles with the closure of their joints,which has been an effective solution avoiding washing out of the joints in ladle lining by the reduction of the penetration of liquid slag and molten steel.Alumina-magnesiacarbon refractories are overall reviewed,in terms of major raw materials,thermal evolution,corrosion and oxidation,and thermomechanical behavior,as well as type,addition and fraction of magnesia used.General commercial products contain 5%-10%MgO and 5%-10%C with a certain amount of metallic aluminum powder,which is believed to facilitate spinel formation at early stage of heating-up,although high magnesia containing AMC bricks are studied and used sometimes.With low ratio of Al₂O₃/C=12.9 and the carbon content of 6.4%C,AMC brick exhibits the highest corrosion resistance.It is important to determine the type,addition and fraction of magnesia used in AMC refractories for demonstrating high corrosion resistance and superior thermomechanical behavior.     

Enhanced corrosion resistance of magnesia-chrome refractories impregnated with zirconia sol

In order to enhance the corrosion resistance to molten vanadates and silicates of middle and upper checker bricks in glass furnace regenerator with petroleum coke as fuel, the present research improved the microstructure, compactness and corrosion resistance of magnesia-chrome refractories by vacuum impregnation with zirconia sol. The results show that the vacuum impregnation of zirconia sol and the increased impregnation times led to the significant increase in the bulk density and decrease in the apparent porosity of refractories, and the impregnated zirconia particles enhanced the corrosion and penetration resistance. The penetrated zirconia particles in the pores decreased the porosity and pore size of refractories, resulting in the inhibited penetration of vanadate and silicate liquid phases during the corrosion process. In addition, the zirconia particles around periclase particles also prevented the reaction between molten corrosion reagent and periclase, thus enhancing the corrosion resistance of refractories. The present study provides an effective method for improving the corrosion resistance of magnesia-chrome checker bricks in regenerator of glass furnace with petroleum coke as fuel.     

水泥窑用烧成富镁白云石砖抗热震性的研究

在烧成富镁白云石砖中加入含锆添加剂,能显著提高制品的抗热震性能。不同含锆添加剂有不同的效果,加入粒状氧化锆的效果最佳。抗热震性的改善归功于添加剂所引起的微裂纹,而锆酸钙的形成也起着极其重要的作用。     

水泥回转窑用碱性耐火材料显微结构的控制

根据显微结构特征分析研究了水泥回转窑用无铬碱性耐火材料的性能和发展。这些氧化镁基或白云石基材料,引入低膨胀性且抗侵蚀的加入物改善其显微结构。镁铝尖晶石砖是从直接加入粒状氧化铝、烧成过程中生成原生尖晶石,到直接加入预合成的尖晶石,发展至细粒晶型尖晶石再增强的含电熔尖晶石镁质砖;白云石砖以其良好的对水泥熟料的粘着性而被广泛用于水泥回转窑烧结带,加入氧化镁粉和氧化锆改善其基质增强了抗侵蚀性及抗热震稳定性;新发展的氧化镁-铁铝尖晶石和氧化镁-锰铝尖晶石耐火材料以其优越的柔性而被用于轮箍部位。     

A novel approach to prepare graphite nanoplatelets exfoliated by three-roll milling in phenolic resin for low-carbon MgO-C refractories

Development of nano carbon containing magnesia graphite refractories to reduce the total carbon content is urgently required for application of low carbon steel smelting. In this work, a novel approach to prepare graphite nanoplatelets (GNPs) by exfoliating flake graphite (FG) in the medium of phenolic resin (PF) via three-roll milling, and the as-prepared GNPs/PF mixtures were used in MgO-C bricks to develop a novel low carbon magnesia-carbon refractories (LCMCRs). The results show that with the increasing of exfoliation times, the FG was constantly thinned, and the production of GNPs had thicknesses of 10–20 nm after exfoliation for 16 times. As a carbon source for LCMCRs, the GNPs and/or GNPs/PF mixture with 2 wt. % carbon could improve the comprehensive performance of the LCMCRs, including the higher cold crushing strength and hot modules of rupture, the better oxidation resistance and slag corrosion resistance. The GNPs continue uniformly dispersed and wrapped with magnesia aggregate, playing an importance role and positive impaction on the corrosion resistance of refractories.     

Corrosion behavior of carbon,Al2O3, and MgO refractories during the preparation of a Ti–Si–Al alloy via the aluminothermic reduction of a Ti-bearing blast-furnace slag

The extraction of Ti from Ti-bearing blast-furnace slag (TBFS) via aluminothermic reduction to prepare Ti–Si–Al alloy has several promising applications. However, the refractories of the furnace lining can dissolve into the molten slag and change the composition of the slag, not only shortening the life of the refractories, but also influencing the preparation of Ti–Si–Al alloys for industrial applications. The main purpose of this study was to explore the corrosion behavior of refractories (carbon, alumina, and magnesia bricks) and determine the most suitable refractories for the aluminothermic reduction of TBFS. Herein, for the first time, the dissolution equilibrium of refractories during the aluminothermic reduction of TBFS and its effect on aluminothermic reduction were revealed. The results revealed that the alumina and magnesia bricks were more effective for obtaining bulk Ti–Si–Al alloy and avoiding high mass loss of the Ti–Si–Al alloy compared to the carbon bricks. Furthermore, the corrosion of alumina and magnesia bricks increased with an increase in the content of the added CaO; however, the corrosion of the alumina bricks was more severe compared to the magnesia bricks. In addition, the largest extraction ratio of Ti (maximum value: 99.85%) was achieved when magnesia bricks were employed. The results of this study indicate that magnesia bricks are the optimal refractory for the preparation of Ti–Si–Al alloy via the aluminothermic reduction of TBFS. This work provides important experimental information for the industrial application of the aluminothermic reduction of TBFS in the preparation of Ti–Si–Al alloys.     

Role of ZrO2 in sintering and mechanical properties of CaO containing magnesia from cryptocrystalline magnesite

As main components of magnesia-based refractories, magnesia exhibits excellent properties such as high refractoriness and good basic slag corrosion resistance. However, magnesia produced from CaO containing cryptocrystalline magnesite has limited application owing to the low hydration resistance and poor thermal shock resistance (TSR). This work aimed to investigate the reinforcing effects of microscale monoclinic ZrO₂ on free CaO containing magnesia for optimizing mechanical properties, TSR and hydration resistance. The results showed that adding ZrO₂ could promote the removal of the open pores, strengthen the interface bonding between various grains and produce crack deflection, which improved flexural strength and fracture toughness. As a result, the TSR of the specimens was enhanced effectively due to increased strength and toughness and reduction in the thermal expansion coefficient. Besides, as the ZrO₂ was introduced, hydration resistance of the specimens improved significantly, mainly attributing to the decrease in apparent porosity and elimination of the free CaO by forming CaZrO₃ and cubic ZrO₂ phases.