Al对MgO—C—Al系耐火材料的显微结构及特性的影响

1.前言 为了改进含碳耐火材料在高温下容易氧化和高温强度低等缺点,对其添加了金属、合金及碳化物这样的非氧化物。在镁碳系耐火材料中,Al是最常用的金属,至今对其使用效果等仍在研究。其中,京田等人报道说,把Al-C系混合压制成型的试样,在氩气气氛中于各     

Thermal Shock Resistance of Bauxite-based β-Sialon Bonded Corundum Materials

Thermal shock resistant properties of reaction sintered bauxite-based β-Sialon bonded corundum have been investigated, and the results are compared with those of Al2 03 based counterpart. It is found they all have very good thermal shock resistance. Their residual strength ratios after one thermal shock cycle at AT=1200℃ and AT=1350℃ are61% -73% and53% -65% respectively. Their critical temperature difference(TSR) is 600℃-800℃. TSR parameters are calculated based on thermal expansion, modulus of elasticity,and fracture toughness determined. The reasons for improving TSR of these composite materials are discussed.Key words: Thermal shock resistance, Bauxitebased, Sialon, Corundum     

添加铝和硅的MgO-C耐火材料在空气中的氧化

镁碳砖内碳的相氧化的预防对于提高镁碳砖的性能是极其重要的。在空气中,添加铝和硅的金属粉末对MgO-C砖氧化的影响,在1200～1500℃的温度范围内,通过按固定时间间隔记录质量损失进行了研究。超过1450℃添加铝或超过1550℃添加硅时,观察到氧化完全被阻止了。采用光学显微镜、电子数据分析装置和X射线衍射检验了表面层。在热力学上,该机理是以铝或硅的气化以及它们在砖表面的氧化为基础进行的,结果产生了一个MgO·Al_2O_3或2MgO·SiO_2的连续层,因此抑制了碳的氧化。     

Reaction Sintering of β-sialon／Al2O3／SiO2 Mixtures in Flowing Nitrogen at High Temperatures

β-sialon/alumina/silica mixtures were sintered in flowing nitrogen at 1500℃ and 1600℃ respectively.The sintering properties and morphology of samples were investigated by SEM, EDS and XRD. Results show that sintered properties of the samples are influenced by soaking temperatures and compositions. Bulk densities of samples are increased with the increase of the soaking temperature, whereas the apparent porosities are decreased. Mass loss of the sintered samples at 1500℃ is lower than that at 1600℃, but all the mass loss remains approximately constant with the increase of sialon content. From the point of thermodynamic analysis,Complex chemical reactions take place in samples during sintering process and the volatile of SiO (g) is responsible for the mass loss of samples. Compared to cross section microstructure of β-sialon/Al2O3/SiO2 mixtures sintered in coke powder bed consisting of the dense center with well-developed column of sialon phase, the transitional part with needle like grain nitrogen-containing phase and the loose part with short granular Al2 O3 phase, those of mixtures sintered in flowing nitrogen is of well-developed sialon in dense center and slightly loose part with sialon debris.     

高铝耐火材料在电弧炉中的应用

近十年来在铸铁及铸钢工业中的进展主要表现在某些冶炼窑炉,特别是电弧炉操作方面的巨大变化。废钢的预热、氧气吹管、炉壁及炉顶水冷板、出钢口关闭系统等使电弧炉的操作条件更加严酷,从而要求改善耐火材料的性能。查明,炉子的操作效果和经济效益,以及炉子的维护在很大程度上取决于耐火材料对炉料熔炼时产生的侵蚀作用的抵抗能力。制约耐     

废弃物熔融炉用耐火材料

介绍了对于焚烧城市垃圾、产业废弃物、下水污泥等发生的焚烧灰和飞灰进行熔融处理，减轻环保负担，实现无害化和有效利用的熔融炉的型式及其耐火材料。熔融炉大致分为灰熔融炉和气化熔融炉。熔融炉根据炉子型式、处理物性状、运转条件，分别使用铝铬质、镁铬质等含铬耐火材料和高铝质、碳化硅质、石墨质、锆英石质、尖晶石质、白云石质等无铬耐火材料，并指出了无铬耐火材料的今后发展方向。同时，还介绍了环保以外的钢铁、有色金属、水泥、玻璃、化工等工业窑炉用耐火材料。     

氮化硅铁在炭系耐火材料中的反应性

研究了氮化硅铁在炭系耐火材料中的反应性及其在高炉出铁口等方面的应用。     

Fe2O3对天然原料合成Al4SiC4/Al4O4C复合耐火材料的影响（英文）

以焦宝石、活性炭和铝粉为原料并添加Fe2O3后制备了Al4SiC4/Al4O4C复合耐火材料。利用化学分析、X射线衍射和扫描电镜研究了Fe2O3对所制备复合材料的物相组成和显微结构的影响。结果表明：在烧结过程中,从1400℃开始,Fe2O3转变为低熔点物相Fe3Si,产生液相促进Al4SiC4成核、细化晶粒,同时包裹Al4SiC4。此外,未添加Fe2O3的样品中生成的Al4O4C短纤维,Fe2O3的加入使得Al4O4C相变为细小的晶粒。

Abstract：

Al4SiC4/Al4O4C composite refractory was synthesized by using flint clay,activated carbon and aluminum powders as the raw materials and Fe2O3 as the additive. The effects of Fe2O3 on the phase composition and microstructure of Al4SiC4/Al4O4C composite refractory were investigated by chemical analysis,X-ray diffraction and scanning electron microscopy. The results show that Fe2O3 transforms into a low melting point phase of Fe3Si above 1 400 ℃,which leads to generate liquid phase and promote the nu-cleation and grain refinement of Al4SiC4 phase. Fe3Si also could coat Al4SiC4 grains. Moreover,the morphology of Al4O4C in Al4SiC4/Al4O4C composite refractory without addition of Fe2O3 is short fibrous-like structure,but changes into fine granules structure after adding Fe2O3.     

在煤气化环境中采用改进的尖晶石基耐火材料

介绍了新研发的一种耐火材料体系,这项技术可以有效降低气化炉用衬里耐火材料的能源消耗。已经研发出专用于煤气化环境的材料,工作已经完成开发并应用,利用低成本的胶体涂层法来提高耐火材料的抗侵蚀能力,这种轻质砖可以替代高热导率的尖晶石材料作为备用耐火材料。本文系统论述了材料的研发、实验室测试和评估,结果显示该材料在正常工况条件下,尽管化学组成和过程稍有变化,但是化学还原反应和机械损毁明显减少。     

MgO—C—Al耐火材料的热化学稳定性

了解氧化镁-石墨-铝系的热化学稳定性对于设定这些砖的蚀损机理是至关重要的。然而热动力学数据虽易于获得,但对这些数据缺乏全面说阴。本文采用挥发性和Ellingham图对Mg-O、Mg-O-C和Mg-O-C-Al等非凝聚系统的热动力稳定性进行了评定。这些图可以深入了解氧和金属气体局部压力并示明在这些系统中受热动力因素影响突出的相。     

New refractory materials for the aluminum industry

A technology for production of andalusite-based refractory components for the lining of anode firing kilns is described. The formulation for a low-cement castable resistant to attack by molten aluminum is proposed. __________ Translated from Novye Ogneupory, No. 4, pp. 109–111, April, 2006. Based on materials reported to the conference “Aluminum of Siberia-2005.”     

中国耐火原料的新近发展

介绍了过去几年中国几种主要耐火原料,如矾土基原料(包括电熔刚玉、尖晶石、莫来石)、镁质原料(包括大结晶98电熔镁砂、高铁高钙镁砂、电熔或烧结镁铬砂)和非氧化物材料(包括氮化硅铁、氮化硅)的最新发展,同时讨论了非氧化物结合的新型材料在未来几年的发展趋势.     

建立完善的计量工作体系 保证耐火材料产品质量

叙述了建立计量工作体系对耐火材料产品质量的重要作用,并针对耐火材料行业特点,着重论述建立计量工作体系的一般模式     

自主创新,发展新型优质耐火材料

讨论了今后我国耐火材料品种、结构、调整、升级的问题,应当以自主创新为主旋律,充分利用资源优势发展有自己特色的新型质合成原料和高效制品,还介绍了近两三年来这方面的一些科技成果。     

耐火材料工业热工窑炉的技术进步

介绍了我国近年来耐火材料工业热土窑炉的最新成果，阐述了超高温隧道窑、超高温回转窑、超高温竖窑、轻型结构节能梭式窑等新型窑炉的原理、特点、系统配置及使用情况。这些新型窑炉的问世，大大地促进了我国耐火材料新品种的发展，不仅使耐火制品质量上了一个新台阶，单位产品热量消耗也大大降低。     

Hydration of refractory oxides in castable bond systems—II: alumina–silica and magnesia–silica mixtures

Isothermal conduction calorimetry was used to investigate binary mixtures of hydratable alumina-fumed silica and reactive magnesia-fumed silica for 22 h at 20 and 30 °C. Neither alumina nor magnesia formed a crystalline hydration product with silica under these experimental conditions. Silica tended to retard the hydration of magnesia, whereas it acted as an inert diluent when added to alumina.     

Reactive alumina production for the refractory industry

In this study, fine reactive alumina powder production was investigated using Bayer gibbsite as a starting material. Experimental studies consist of three steps; in the first step, the soda content was reduced by means of boric acid and distilled water. In the second step, the effect of heating rate and calcinations temperature on crystal size, phase transformation and surface area were investigated and characterization of the powders was performed by means of XRD and SEM analyses. In the third step, the powders obtained optimum conditions were ground in an attritor mill and then particle size distribution and surface area were measured. The soda content of the gibbsite was reduced from 0.325 to 0.05% by H₃BO₃ treatment, calcination at 1200 °C and then washing in distilled water. The higher the heating rate, the smaller the crystal size is. Alumina ceramics with a density higher than 94.70% of theoretical density were obtained.     

PTFE-纳米粒子复合材料的制备及性能研究

使用硅烷偶联剂KH560对纳米Si3N4和Al2O3进行了改性,随后将其分别填充到PTFE树脂中制备了PTFE-纳米粒子复合材料,研究了不同KH560含量对复合材料密度、硬度,力学性能及摩擦磨损性能的影响。结果表明,纳米Si3N4经质量分数6%的KH560改性后,填充制备的PTFE复合材料其拉伸强度、断裂伸长率与未经改性纳米Si3N4填充复合材料相比,磨耗量高、硬度低,但密度、摩擦系数等相差不大;纳米Al2O3分别经质量分数4%的KH560改性后,对应复合材料的拉伸强度和断裂伸长率大于未改性纳米Al2O3填充复合材料,但密度、硬度、磨耗量及摩擦系数等相差不大。     

Analysis of the intragranular microstructure in ceramic nanocomposites and their effect on the mechanical properties

The formation of intragranular microstructure in Al₂O₃/ZrO₂ and Si₂N₂O/Si₃N₄ nanocomposites was analyzed, and the effect of intragranular microstructure on the mechanical properties of nanocomposites was investigated. Results suggest 3 requisite conditions for the formation of intragranular microstructure and the role of intracrystalline glass phase and scar microstructure. In case of Al₂O₃/ZrO₂, the intragranular microstructure leads to the formation of transgranular fracture, which in turn improves the mechanical properties via strengthening and toughening. On the other hand, in case of Si₃N₄/Si₂N₂O nanocomposites, intragranular microstructure reduces the possibility of bridging, pulling out, and crack deflection, thereby leading to the deterioration of strength and toughness. Based on these results, we can conclude that the formation of intragranular microstructure does not necessarily improve the mechanical properties in all kinds of materials. Rather, the effect of intragranular microstructure on the mechanical properties of nanocomposites is related to the strengthening and toughing mechanism of matrix materials.     

Permeability of carbon refractory materials used in a blast furnace hearth

Permeability of experimental and standard micropore carbon materials, before and after the heat treatment at 1550 °C, was investigated using gas permeability measurements (GP) and mercury intrusion porosimetry (MIP). Permeability of both materials increased after the annealing. Experimental micropore carbon material was less permeable than standard one, both before and after the heat treatment. Measured gas permeabilities were compared with permeabilities determined based on MIP measurements using two different models: Hagen?Poiseuille and Carman?Kozeny equation. Using the inverse problem approach, for the first time Carman?Kozeny constant was determined for micropore carbon materials. Carman?Kozeny model gave more accurate results (i.e. close to gas permeability measurements) than Hagen?Poiseuille model. Performed investigations showed that mercury intrusion porosimetry might be alternative method to investigate infiltration resistance of low permeable materials.