不同碱度渣对刚玉-尖晶石浇注料的侵蚀行为研究

浇注料的抗渣侵蚀性能与钢渣的碱度密切相关。以烧结刚玉、缺陷尖晶石微粉、活性α-Al₂O₃微粉、电熔镁砂细粉和铝酸钙水泥(Secar71)为主要原料,制备了刚玉-尖晶石浇注料,采用静态坩埚法于1 600℃保温3 h进行抗渣试验,并用热力学模拟计算了液相量和液相组成,研究了刚玉-尖晶石浇注料对3种不同碱度渣(1.6、2.3和7.6)的抗渣侵蚀性能。结果表明：刚玉-尖晶石浇注料在高碱度渣中溶解能力有限,在熔渣-耐火材料界面极易形成尖晶石固溶体和六铝酸钙等高熔点物相,形成致密层阻挡熔渣渗透和侵蚀。而其在低碱度渣中溶解度较高,在浇注料-熔渣达到较高反应程度时,才开始形成尖晶石固溶体和六铝酸钙等高温相,无法形成有效的致密层阻止熔渣对浇注料的侵蚀和渗透。因此,刚玉-尖晶石浇注料对高碱度渣抗渣侵蚀能力较强,对低碱度渣抗渣侵蚀能力较弱。     

不同碱度渣对铝镁浇注料的侵蚀行为

以板状刚玉颗粒(≤5 mm)、电熔镁砂粉(≤0.088 mm)、电熔尖晶石粉(≤0.044 mm)、α-Al2O3微粉(d50≤0.7μm)为主要原料,经配料、混料、成型、烘干后制备了铝镁质坩埚试样,采用2种不同碱度的钢包渣(碱度分别为3.40和1.03),通过静态坩埚法对铝镁浇注料进行抗渣试验(1 600℃3 h),分析了抗渣试验后试样的渣蚀指数和显微结构,以研究不同碱度渣对铝镁浇注料试样的侵蚀行为。结果表明,低碱度渣对铝镁浇注料的侵蚀和渗透比高碱度渣严重,这主要是因为不同碱度渣与浇注料反应生成的产物不同。低碱度渣对铝镁浇注料侵蚀时,材料内部CA6和钙铝硅系化合物多相共存的组织以及CA6生成时的体积膨胀效应加剧了渣对材料的侵蚀和渗透;在高碱度渣条件下,渣与材料界面生成了CA2致密层和大量的原位MA,有效地降低了渣对材料的蚀损。     

尖晶石加入量对刚玉-尖晶石浇注料性能的影响

以板状刚玉、尖晶石、氧化铝微粉和纯铝酸钙水泥为原料,研究了尖晶石加入量(质量分数分别为0、3%、6%、9%、12%、15%、18%)对刚玉-尖晶石浇注料性能的影响。结果表明:随着尖晶石加入质量分数在0～18%范围内的增加,试样的高温抗折强度和抗渣性能均逐渐改善;试样的抗热震性呈先下降后上升趋势,以尖晶石加入质量分数为9%时最差;试样1 550℃3 h处理后的冷态强度呈先上升后下降的趋势,以尖晶石加入质量分数为9%时最大。     

尖晶石种类对刚玉-尖晶石浇注料性能的影响

采用板状刚玉颗粒（6～3、3～1、≤1 mm）及细粉（0.045 mm）、电熔尖晶石颗粒（≤1 mm）及细粉（0.045 mm）、烧结尖晶石颗粒（≤1 mm）及细粉（0.045 mm）、活性尖晶石微粉(d₅₀=1.82μm)、活性α-Al₂O₃微粉(d₅₀=1.68μm)、Secar 71水泥等原料制备了刚玉-尖晶石浇注料。研究了不同种类尖晶石（电熔尖晶石、烧结尖晶石、烧结尖晶石+活性尖晶石）对浇注料性能的影响。结果表明：1)在刚玉-尖晶石浇注料中引入不同的尖晶石对试样经110℃保温24 h烘干后的抗折强度和耐压强度影响不大，但采用电熔尖晶石能降低加水量，提高流动性，得到优良的施工性能；2)采用电熔尖晶石有利于材料的抗渣侵蚀性能，但在抗渣渗透性及抗热震性方面，烧结尖晶石更占优势；3)加入适量的活性尖晶石微粉可以弥补烧结尖晶石的不足，提高浇注料的可施工性能，但对抗热震性会产生一定负面影响。     

以微孔刚玉-尖晶石骨料替代刚玉骨料制备刚玉-尖晶石浇注料

为提高钢包工作衬用刚玉-尖晶石浇注料的保温性能，以微孔刚玉-尖晶石骨料部分或全部替代同粒级的烧结刚玉骨料，制备了刚玉-尖晶石浇注料，对比研究了不同骨料对浇注料的体积密度、气孔率、力学强度、热导率、抗渣性等的影响。结果表明：采用微孔刚玉-尖晶石骨料部分或全部替代同粒级的烧结刚玉骨料制备的刚玉-尖晶石浇注料，其体积密度和热导率均明显降低，抗渣性能与传统烧结刚玉骨料制备的浇注料相当。将其用于钢包工作衬，有助于钢包减重，提高钢包保温性能。     

HiPerCem水泥对刚玉-尖晶石浇注料抗渣性的影响

以板状刚玉、尖晶石细粉和活性α-Al2O3微粉为主要原料,使用HiPerCem水泥作为结合剂制备刚玉-尖晶石浇注料,对比研究了HiPerCem水泥与Secar71及CMA72水泥在浇注料中的凝结行为及其对浇注料常温物理性能、抗渣性能的影响.结果 表明,在保持引入浇注料中一铝酸钙含量为1.8％,尖晶石含量为10％的情况下,HiPerCem水泥结合浇注料的凝结速度居中,脱模及烘干强度较另外2种水泥结合浇注料的低.抗渣侵蚀实验表明,以HiPerCem水泥为结合剂的浇注料因引入的CaO含量较CMA72和Secar71水泥结合浇注料低,大尺寸气孔少,具有较好的抗渣性;而CMA72水泥结合浇注料因试样中大尺寸气孔比例较高,熔渣渗透严重,未能发挥出其水泥中微晶尖晶石相改善抗渣性的优势.     

尖晶石粒度对高纯刚玉-尖晶石浇注料性能的影响

研究了尖晶石粒度对高纯刚玉 -尖晶石浇注料的抗折强度、抗热震性、抗侵蚀性等性能的影响。实验表明 :(1)随着配料中尖晶石颗粒含量的增加 ,试样的烧后强度呈先升高后降低趋势 (烘后强度变化不明显 ) ,烧后收缩减少 ,然后变为膨胀 ;(2 )尖晶石细粉与颗粒为 1:3的试样抗热震性较好 ;(3)对于高碱度渣 ,尖晶石颗粒加入量较多的试样抗侵蚀性较好 ;(4)对于低碱度渣 ,尖晶石细粉加入量较多的试样抗侵蚀性和抗渗透性均较好。     

烧结刚玉骨料致密度对刚玉-尖晶石浇注料性能的影响

为了研究烧结刚玉骨料致密度对刚玉-尖晶石浇注料性能的影响,首先以工业Al₂O₃粉为原料制备不同致密度的烧结刚玉;然后以不同致密度的烧结刚玉为骨料制备刚玉-尖晶石浇注料,并研究了刚玉-尖晶石浇注料的致密度、强度、抗热震性和抗渣性等性能。结果发现：1)随着工业氧化铝粉成球坯体致密度的增大,制成的烧结刚玉的致密度和晶粒尺寸逐渐增大。2)随着烧结刚玉骨料致密度的增大,刚玉-尖晶石浇注料的需水性减小;烧后浇注料的致密度和常温强度增大,抗热震性变差。抗渣侵蚀性除采用体积密度为3.45 g·cm^-3的烧结刚玉骨料的浇注料明显较差外,其他浇注料的差别不大。3)综合考虑,烧结刚玉骨料的体积密度以3.51～3.55 g·cm^-3为佳。因此,不能片面地认为烧结刚玉的体积密度越大越好;过高的体积密度会导致耐火材料抗热震性能变差,并增加耐火材料单重。     

促凝剂对刚玉-尖晶石质喷射浇注料性能的影响

本文研究了促凝剂对添加尖晶石细粉和镁砂细粉的两种刚玉-尖晶石质喷射浇注料性能的影响,结果表明:添加镁砂细粉后,喷射浇注料的流变性能下降;通过四种促凝剂对刚玉-尖晶石质喷射浇注料性能的影响研究,发现加入促凝剂后,含镁砂的喷射浇注料增粘变稠的速度快,施工时附着率高;铝酸钠和氢氧化钠复合的促凝剂与两种有机物复合的促凝剂都能使喷射浇注料快速增粘变稠、凝结硬化,但含Na+促凝剂的引入,提高了材料中Na+的含量,降低了喷射浇注料的高温抗折强度、热震稳定性能、抗渣侵蚀性能和常温物理性能.     

不同组成尖晶石对MgO-尖晶石浇注料抗渣性能的影响

采用静态坩埚法和动态回转法研究了不同组成尖晶石对MgO-尖晶石浇注料抗渣性能的影响,并采用扫描电镜和能谱分析测定了渣蚀残样中尖晶石的存在形式和化学组成。结果表明,在基质组成相同的情况下,添加富铝尖晶石的浇注料在加热过程中可生成较多的原位生成尖晶石,原位生成尖晶石吸收渣中FeO3、CaO能力是合成尖晶石的3～5倍,因而该浇注料具有较好的抗渣性能。     

刚玉-尖晶石浇注料基质部分最佳配比研究

以致密电熔刚玉为骨料,研究了刚玉-尖晶石浇注料基质中电熔刚玉、电熔镁砂和烧结尖晶石细粉的配比关系,测试了材料的物理性能和抗渣侵蚀性能。结果表明：在电熔刚玉细粉与电熔镁砂细粉之比为72：28,尖晶石细粉加入量为15％时,材料具有合理的线变化率和良好的抗渣性能。     

Corrosion resistance of Al–Cr-slag containing chromium–corundum refractories to slags with different basicity

Al–Cr slag is the solid waste generated by the smelting of Cr metal. It presents a range of environmental hazards. This study addressed the corrosion resistance of Al–Cr slag containing chromium–corundum refractories to slags with different basicity. Herein, we provide suggestions for the use of Cr–corundum of different basicity in kilns. Al–Cr slag, brown fused Al₂O₃, and chrome green were used as the raw materials, with pure calcium aluminate cement being used as a binder. The brick samples, prepared using different blends of chrome green and corundum, were fired at 1600?°C, and subsequently subjected to a slag corrosion test. After corrosion by slag of different basicity, the phase composition and microstructure of the sample were analyzed by X-ray diffraction, energy dispersive spectrometer and scanning electron microscopy. There were two major findings. First, Cr–corundum brick made from Al–Cr slag has a better slag corrosion resistance than that made from Cr₂O₃ and brown fused Al₂O₃. Second, Cr–corundum brick made from Al–Cr slag has superior corrosion resistance to slag with a CaO:SiO₂ ratio of 2:1.     

高档钢包浇注料的开发与应用

研究了刚玉的种类、粒度及加入量,以及结合剂的种类及加入量对浇注料性能的影响。以刚玉、矾土熟料为骨料,高档电熔镁砂粉、刚玉粉为基质,开发出了更加适合国情,价廉物美的高档钢包浇注料。该产品在马钢三炼钢７０ｔ钢包上使用后证明,其抗剥落性好,蚀损率小,且包壁整体光滑,达到了上下同步蚀损的理想效果。     

低硅刚玉自流浇注料的研制

以刚玉为主要原料 ,并辅以纯铝酸钙水泥和其它外加剂 ,研制出了Al2 O3含量达 98% ,CaO含量 2 %的自流浇注料 ,其烧后体积密度 2 .98g·cm- 3,常温耐压强度 94.4MPa ,常温抗折强度2 0 .4MPa,均超过了国外同类产品的性能指标。     

铝镁浇注料的抗渣侵蚀机理

采用静态坩埚法进行了铝镁浇注料的抗渣侵蚀试验 ,从动力学和热力学角度分析了铝镁浇注料的抗渣侵蚀机理。结果表明 :浇注料的熔渣侵蚀过程受化学反应和扩散的混合控制 ;熔渣侵蚀的表观活化能约为 4 2 4 .8kJ·mol- 1;渣中CaO与Al2 O3反应生成高熔点的CA6 ,抑制了熔渣的进一步侵蚀 ;渣中CaO含量的不断降低 ,使熔渣的粘度增大 ,渗透能力降低。     

Analysis of corrosion of corundum refractory castables in relation to increased MgO content in dendromass ashes

Biomass ash has a significantly lower proportion of Al₂O₃ and higher proportions of K₂O, CaO and SiO₂ than coal ash. Biomass combustion in power plants increases demands on refractory linings and metal fittings in boilers. Grates and linings of combustion chambers in furnaces and boilers are more susceptible to clogging and are degraded by bio-ash slag. The results of this study suggest that the addition of approximately 2% of powder magnesite waste to the wood-chip fuel can significantly mitigate ash slagging and also corrosion of the corundum refractory material. With regard to the resulting increased MgO content in the dendromass ash, the corrosion of corundum refractory material was studied. The MgO content in the ash was increased by adding powder magnesite waste to ash samples. The results of corrosion tests (1450 °C/7 h) showed that ash slag with MgCO₃ addition corroded the corundum material less. Analyses of the post-mortem slag and corrosion interface confirmed: (i) higher K₂O concentration in the ash caused increased corundum material corrosion by both vapours (g-s) and melt (l-s); (ii) K₂O reacted with Al₂O₃ at the corrosion interface and also penetrated intensively into the fine-grain matrix by surface diffusion; (iii) MgO remained in the slag; (iv) increased Al₂O₃ content in the molten slag initiated a liquation of MA-spinel. These results (especially MA spinel liquation from the slag and K₂O diffusion through the matrix followed by micro-grain dissolution) indicate that replacing the mullite binder phase in the matrix with MgO and/or spinel could lead to improved resistance of the refractory material to biomass ash slag.     

Effect of composite micro-powder added with α-Al2O3 and zirconium basic carbonate on the structure and properties of corundum castable

This article aims to illustrate the influence of the composite micro-powder of α-Al₂O₃ and zirconium basic carbonate (ZBC) on the microstructure, mechanical and thermal properties, and slag resistance of corundum castable. The results show that the addition of the composite micro-powder to corundum castable sintered at 1550 °C optimized its pore structure, which presented an apparent porosity of 16.8% and a slump in pore size from 10.80-45.72 μm to 0.36–1.83 μm. The ZrO₂ dissolving from ZBC combined with corundum matrix to form “intergranular” and “intragranular” submicron structures, which promoted the densification of matrix structure and improved the strength of castable by 25.8%–42.9%. In terms of slag resistance, castable with composite micro-powder saw an absorption of liquid slag in micropores and a Cr-rich complex spinel blocking layer with high melting point during slag erosion. Moreover, the in-situ ZrO₂ could enter slag to boost its viscosity, thus inhibiting the penetration capacity. Consequently, the penetration and erosion ratios of castable reduced by 6.32% and 83.99%, respectively.     

Corrosion of alumina-magnesia castable by high manganese steel with respect to steel cleanness

High manganese steel has been widely used in the national defense, automobile and petrochemical industry fields due to its excellent wear resistance and low temperature toughness. Alumina-magnesia refractory plays a significant role in high manganese steel smelting. In this paper, the interaction between alumina-magnesia castable and high manganese steel, and its effects on the quality of high manganese steel were analysed. The Fe and Mn of the molten steel transferred into the castable during the early smelting stage, so a reacted metamorphic layer with lower melting point was formed between the refractory castable and high manganese steel. With the prolongation of smelting time, the thickness of the reaction layer and number of molten steel droplets entrained into the refractory castable-high manganese steel reaction layer were increased under dynamic conditions. Some refractory particles were loosed and dropped into the reaction layer, which accelerated the erosion of the refractory castable, causing an increase in the total [O] content in the steel. An isolation layer of (Fe, Mg, Mn)Al₂O₄ composites began to form after 30?min and the total [O] content in the steel decreased gradually to below 10?ppm after 60?min. The formation of an isolation layer prevented the corrosion of the refractory castable and guaranteed steel cleanness within 90?min of smelting, but resulted in a 2% decrease of the Mn content in the high manganese steel during the smelting process.