铝铬耐火材料抗侵蚀的热力学模拟

采用了热力学模型模拟方法,计算模拟了铝铬耐火材料与熔融还原炼铁渣的反应过程.计算结果表明三种耐火材料(10Cr2O3-90A12O3,50Cr2O3-50Al2O3和90Cr2O3-10Al2O3)与熔渣在1500℃条件下发生反应生成尖晶石相MgCr2O4和MgAl2O4.反应后熔渣中Al2O3和Cr2O3含量有所增加,说明在此条件下耐火材料在一定程度上发生了溶解,Al2O3和Cr2O3因而渗入熔渣.热力学模拟能够预测由于耐火材料的溶解作用使得该熔融还原炼铁渣对铝铬耐火材料的渗透深度更深.     

纳米Fe2O3对镁铬耐火材料烧结及力学性能的影响

在镁铬耐火材料中添加纳米Fe2O3,研究了它对镁铬耐火材料烧结性能与常温力学性能的影响.结果发现,在相同的工艺条件下,加入1%(外加)的纳米Fe2O3即可使镁铬砖的烧成温度降低150℃左右,并在相同烧成温度下能使试样的常温抗折强度和耐压强度大幅度提高.分析认为,在镁铬耐火材料中添加少量纳米级Fe2O3,可促进MgO-FeO固溶体中Cr3+和Al3+含量的提高,增强镁铬砖的直接结合程度,从而提高其力学性能.     

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。     

纳米Al_2O_3和Cr_2O_3对镁铬材料烧结与力学性能的影响

利用纳米粉的粒径小及活性高等特性,在镁铬材料中加入不同质量分数(分别为2%、4%、6%)的纳米A l2O3或纳米Cr2O3粉体,研究了这两种纳米粉取代相应的微粉后对不同温度烧成的镁铬耐火材料烧结与力学性能的影响。结果表明:适量地用纳米粉体取代相应微粉可有效改善镁铬材料的烧结,提高其常温与高温力学性能,且烧成温度越低,纳米粉对镁铬材料性能的提高作用越明显;在本试验的镁铬材料的颗粒级配条件下,两种纳米粉的加入质量分数均以4%为最佳;纳米A l2O3的加入能降低镁铬质耐火材料的烧结温度,加入4%质量分数的纳米A l2O3可降低约100℃。     

铁浴式熔融还原渣对镁铬材料侵蚀的研究

以市售w(Cr2O3)=26.02%的电熔再结合镁铬砖和自制预合成的不同FeO含量的铁浴式熔融还原渣为研究对象,采用旋转圆柱法,研究了铁浴式熔融还原渣中FeO含量(其质量分数分别为0、5%、10%和15%)和试验温度(1 450、1 500、1 550和1 600℃)对镁铬砖试样侵蚀量、显微结构的影响。结果表明:(1)不含FeO的渣对镁铬试样的侵蚀量大于FeO含量(w)为5%的渣,渣中FeO含量(w)为5%~15%时,随着FeO含量的增加,镁铬试样的侵蚀量增大,侵蚀加剧;(2)温度是影响镁铬材料抗渣性能的重要因素之一,温度提高,熔融还原渣对耐火材料的侵蚀加剧。     

耐火喷补料的形成工艺

炼钢、炼铜、炼铝和玻璃等行业对耐火材料使用条件要求比较苛刻 ,氧化铝质耐火材料由于具有良好的抗热震性 ,因而得到广泛的应用。利用陶瓷焊接喷补技术对氧化铝质耐火材料表面进行修补 ,可进一步提高耐火材料的使用寿命。陶瓷焊接喷补技术所用的混合物包括含氧化铝的耐火材料、金属易燃物和添加剂。含氧化铝的耐火材料从矾土 (Al2 O3·2H2 O)、莫来石 (3Al2 O3·2SiO2 )、烧结氧化铝 (Al2 O3)和镁铝尖晶石中选取 ;金属易燃物在混合物中的含量至少占 5% ,易燃物可以是金属铝、镁、锆、铬中的一种或几种 ,但金属铝至少占 3 0 % ;添加剂从…     

废弃物熔融回转窑用耐火材料的损毁

介绍了处理废弃物回转窑式熔融炉及其耐火材料。回转窑式熔融炉能够在回转窑内同时进行气化的熔融，具有投入物的大小、形状之自由度大等优点。回转窑式熔融炉使用的耐火材料主要是Al2O3-Cr2O3-ZrO2砖，其中包括低Cr2O3砖D和高Cr2O3砖E。在实际使用中，高Cr2O3砖E由于具有优异的耐蚀性，所以获得了非常好的使用效果，其蚀损量是低Cr2O3砖D的三分之一。     

镁锆砖和镁铬砖的抗RH炉渣侵蚀性对比

为取代RH炉用镁铬材料,以电熔镁砂为主原料,分别加入单斜锆、脱硅锆、单斜锆与脱硅锆的混合粉、锆英石制备了ZrO2质量分数分别为15%和20%的镁锆砖,并利用静态坩埚法对比研究了镁锆砖和镁铬砖的抗RH炉渣侵蚀性。结果表明:对于Al2O3含量高且碱度(CaO/SiO2比)大的RH炉渣,镁锆砖抗侵蚀性能优于镁铬砖的;镁锆砖的侵蚀机理是砖中的ZrO2与渣中的CaO迅速反应,形成高熔点物相CaZrO3,能堵塞砖中的孔隙而形成致密保护层,从而阻止钢渣对镁锆砖的进一步侵蚀;而镁铬砖的侵蚀机理是渣中的Al2O3、Fe2O3等R3 和镁铬尖晶石中Cr3 交换,渣与砖反应生成的镁铝尖晶石和镁铁尖晶石使得材料变性,同时由于体积效应使镁铬材料鼓胀开裂,从而导致镁铬砖的严重侵蚀。     

垃圾熔融炉用无铬耐火浇注料的开发

过去主要采用Al2O3-Cr2O3质耐火材料作为垃圾熔融炉内衬,然而此类材料的Cr2O3可转变为有毒的六价铬。从无铬条件出发,本文主要就MgO-MgO·Al2O3-ZrO2浇注料的开发进行了研究。采用旋转侵蚀实验装置和EPMA,重点研究了直接加入尖晶石、反应生成二次尖晶石、加入ZrO2等对MgO-MgO·Al2O3-ZrO2浇注料性能的影响。     

熔融炉用无铬耐火材料

1 序言 如今环境问题已经成为全球性问题，废弃物的处理方法以前是采用焚烧和填埋，现要求熔融处理以便实现无害化和减容化。熔融炉中发生的炉渣成分是低碱性的(C／S=0．5～1．2)，而且含有许多碱成分(Na_2O，K2_O)以及酸性成分(Cl，SO_3)，所以熔融炉的内衬耐火材料严重受到炉渣侵蚀，故常用Cr2O_3质耐火材料。但是，由于存在生成六价铬的问题，所以希望出现不使用Cr_2O_3的耐火材料，也就是无铬耐火材料。本文介绍耐用性相当于镁铬质或铝铬质耐火砖的熔融炉用无铬耐火材料的研究经过和工业试验结果。     

Fabrication and Properties of Closed-pore Al_2O_3-based Refractory Aggregates

A novel Al_2O_3-based refractory aggregate with closed-pore structure was fabricated utilizing superplasticity with submicro-sized Al_2O_3 and MgO as raw materials,and SiC as a high temperature pore-forming agent.The effect of MgO on porosity,phase composition and microstructure of the refractory aggregate has been investigated. For comparison,the common Al_2O_3-based refractory aggregates and porous ones with open-pore structure were also prepared. The results indicate that the closed porosity of Al_2O_3-based refractory aggregate increases as the content of MgO increases. When the content of MgO is 15 mass%,the closed and apparent porosities are 14. 5% and 1. 1%,respectively. The main phase compositions are Al_2O_3 and MgAl_2O_4. The formation mechanism of closed pores is that the fine-crystallinegrain Al_2O_3 ceramic possesses superplastic deformation ability after adding MgO at high temperatures. When SiC powder is added to the Al_2O_3 ceramic,the generated gases by the reaction of SiC at the sintering temperature can provide a pressure to make grain boundaries slide. Then,the gases are enclosed by crystalline grains to form the closed pores. The slag corrosion resistance of the fabricated closed-pore Al_2O_3-based refractory aggregate is better than the common refractory aggregate and porous ones.     

Corrosion mechanism of magnesia-chrome refractory bricks with FetO-SiO2-Cr2O3 copper converter slag

The paper investigates the effect of Cr₂O₃ on the resistance of magnesia-chrome refractory bricks to copper converter slag. The static crucible method was employed to carry out the slag resistance experiment. The corrosion of magnesia-chrome refractory bricks under the action of Fe_tO-SiO₂-xCr₂O₃ (x = 0–5 wt%) slag at 1300 °C was discussed. The microstructure of the corroded sample was analyzed by XRD and SEM-EDS to elucidate the corrosion mechanisms of magnesia-chrome refractory bricks with Fe_tO-SiO₂-Cr₂O₃ slag. The results indicated that the permeability index of the slag-resistant samples gradually decreased with increasing Cr₂O₃ content in the Fe_tO-SiO₂-Cr₂O₃ slag. Combined with SEM and XRD characterization, the MgO in the refractory reacted with FeO and SiO₂ in the molten slag, leading to dissolution and reaction corrosion of the refractories. Meanwhile, forming a (Mg, Fe)O solid solution layer in corroded samples can prevent further chemical reactions and high-temperature dissolution between the Fe_tO-SiO₂-Cr₂O₃ slag and refractories. With the addition of Cr₂O₃ in the Fe_tO-SiO₂-Cr₂O₃ slag, the corrosion effect of slag on refractories was weakened, and the (Mg, Fe)O solid solution layer became thinner. The magnesia-chrome refractory bricks showed excellent slag resistance when the Cr₂O₃ content in the copper converter slag was 5 wt%.     

Influence of chrome-bearing sols vacuum impregnation on the properties of magnesia-chrome refractory

Two kinds of nanosized chrome-bearing sols, i.e. Cr₂O₃ precursor sol and MgCr₂O₄ spinel precursor sol, were obtained by homogeneous precipitation. Properties of the sol vacuum impregnated magnesia-chrome refractory, such as bulk density, cold crushing strength, pore distribution, and chemical composition, etc., are superior to those of the un-impregnated sample. SEM micrographs show a different microstructure of the impregnated sample as compared to the un-impregnated one. The influence of vacuum impregnation on copper slag corrosion resistance of magnesia-chrome refractories has also been evaluated. The results show that both sols could improve the magnesia-chrome bricks corrosion resistance in impregnation.     

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.     

含磁性γ-Fe_2O_3核的TiO_2/Al_2O_3催化剂的制备及光催化性能

TiO2作为光催化剂,可有效地用于水处理,但存在催化剂如何回收再利用和反应器怎样放大设计的问题。该文提出了含磁性核的TiO2催化剂的合成方法,并对典型污染物的降解作了动力学研究,力求解决此类问题。首先,采用共沉法和溶胶-凝胶法制得磁载光催化剂TiO2/A l2O3/γ-Fe2O3,并对该催化剂分别用TEM和XRD进行了形貌和晶相表征。随后,研究了该催化剂对可溶性染料中间体对硝基甲苯邻磺酸(NTS)和直接耐酸大红染料(4BS)的光催化降解性能。结果表明:该催化剂在水溶液中具有良好的分散效果和较高的催化活性,以250 W高压汞灯为光源,经1.5 h的光催化降解,染料去除率可达90%以上;在外加磁场的作用下,催化剂可与液相迅速分离。经实验数据处理,发现NTS在该催化剂上的光催化降解过程符合零级反应动力学模型。     

水泥窑用MgO-MgAl2O4-ZrO2-La2O3复合耐火材料的研究

根据耐火材料和水泥熟料的反应机理,找到一种既可阻止窑皮中C2S相变,又不损害镁铝质耐火材料的高温性能的添加物,开发了一种基于MgO-MgAl2O4-ZrO2-La2O3体系的新型复合耐火材料。该材料具有优异的耐火性能、抗热震性能、挂窑皮性能、抗侵蚀性能和较高的机械强度,是一种替代镁铬砖的理想材料,适用于水泥窑烧成带。     

熔铁催化剂活性与其母体铁氧化物形态和组成的关系(Ⅰ)母体铁氧化物活性次序

以磁铁矿和还原剂为原料采用高温熔融法分别制得Fe_3O_4、FeO和二者不同比例的混合物,研究了FeO的非化学整比性、氧化性和亚稳定性以及以这些氧化物为母体的熔铁催化剂的活性。发现铁氧化物还原后催化合成氨的活性次序为Fe_(1-x)O＞Fe_3O_4＞Fe_2O_3＞任何两种氧化物的混合物。     

Corrosion Resistance of High-Alumina Graphite Based Refractories to the Smelting Reduction Melts

1 Introduction The corrosion resistance of the refractories is one of the imperative problems for the development of smel- ting reduction with iron bath[1 ~4]. The Al2O3-C based refractories have been widely and successfully used in the metallurgy industr…