免养护轻质耐火浇注料的研制

采用轻质页岩陶砂、漂珠、闭孔膨胀珍珠岩为原料 ,以改性固态水玻璃为结合剂研制了免养护轻质耐火浇注料。研究了结合剂、促凝剂及SiO2 超微粉添加量对轻质耐火浇注料性能的影响。结果发现 :当结合剂的用量为 1 2 %～1 5 % ,促凝剂的用量为结合剂的 4.5%～5 .5 %时 ,可保证轻质浇注料具有优良的性能 ;SiO2 超微粉的加入 ,既可以提高浇注料的高温强度 ,又可以改善其使用性能 ,最佳添加量为 5 %左右。研制的免养护轻质耐火浇注料具有体积密度小 ,热导率低 ,耐压强度高 ,易于施工等特点 ,是使用温度在1 1 0 0℃以下的各类加热炉炉衬的理想材料     

高纯铝镁浇注料的研究

对诸多的结合剂进行试验后，选定了两种结合剂作了高纯铝镁浇注料的研究。研究结果表明：对于高纯铝镁浇注料，电熔镁砂细粉的加入量不宜多过，而且因结合剂的种类不同镁砂的加入量也有差异。     

结合剂对氧化铝-碳化硅-碳质铁沟浇注料力学性能和显微结构的影响

分别以水泥、氧化镁-硅灰和硅溶胶三种结合剂制备了氧化铝-碳化硅-碳铁沟浇注料,借助相关测试标准和SEM、EDS、XRD等测试手段对比研究了三种浇注料的力学性能、显微结构和物相组成.研究结果表明:以水泥和硅溶胶结合的浇注料常温强度较大,以氧化镁-硅灰为结合剂的浇注料常温强度最小;硅溶胶为结合剂浇注料高温抗折强度最大,氧化镁-硅灰为结合剂最小.原因在于:尽管以水泥和硅溶胶为结合剂的浇注料在高温烧成时都生成莫来石,但以水泥结合试样中只是在基质中部分生成莫来石晶体,而以硅溶胶为结合剂试样由于硅溶胶分散性好,脱水后微粒活性更高,在试样中均匀生成了大量交错分布的莫来石晶体,且长径比更大,因此显著提高了高温抗折强度;以氧化镁-硅灰为结合剂的浇注料高温生成镁铝尖晶石、镁橄榄石和堇青石,由于镁铝尖晶石促进了碳化硅的氧化,使得结构疏松,强度降低.     

新型MgO-C浇注料的开发

利用纯碳作结合剂开发了MgO-C浇注料,而且其中的含水量较低（4%-5%）。该结合剂系统由特殊的树脂和其它炭素物质组成。这两种组分可保证结合剂具有一定的强度。在高温分解之后,凝固的浇注料中除了含有碳和氧化镁之外,不含任何其它组分。当含水量较低及在最佳的干燥制度和成型方法情况下氧化镁几乎不发生水化。     

高纯铝镁浇注料的研究

对诸多的结合剂进行试验后,选定了两种结合剂作了高纯铝镁浇注料的研究。研究结果表明：对于高纯铝镁浇注料,电熔镁砂细粉的加入量不宜过多,而且因结合剂的种类不同镁砂的加入量也有差异。     

含有2CaO.AlO3.SiO2的高铝水泥的各种性状

本文详细叙述了增加浇注料中作结合剂的高铝水泥中ＳｉＯ２粉的含量，浇注料的物理性能的变化，并延长浇注料的可使用时间。     

一种快干无水泥浇注料用新型结合剂

法国Calderys公司开发了一种用于快干无水泥浇注料的新型结合剂,简称QD NCC结合剂。有研究者对使用该结合剂的黏土质快干无水泥浇注料的透气性、干燥速率、蒸汽压等技术参数的变化进行了试验研究。     

耐火材料用有机-无机复合结合剂的研制

以水泥为结合剂的浇注料中含有CaO,在烧成过程中能够生成低共熔相而影响了其高温性能。为了提高浇注料的高温使用性能,需要在保证浇注料具有一定的常温强度的基础上,研制低水泥或者无水泥的新型结合剂来替代水泥结合剂。以丙烯酰胺体系为基础,探讨了丙烯酰胺系有机-无机结合剂在矾土基浇注料中的实际使用效果。结果表明,浇注料在110℃烘干后的体积密度、显气孔率、耐压和抗折强度等常温性能良好,尤其是抗折强度得到很大的提高。在不同高温烧成后,有机结合剂的浇注料性能得到提高。     

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.     

超低水泥和无水泥浇注料的抗热性及热机械性

制备了两种浇注料，即超低水泥和无水泥浇注料，或是含有高铝水泥或是含有水合氧化铝作为结合剂。对每一种类，制备了两种不同浇注料系统，一种是在其基质中含有氧化铝-二氧化硅混合物，另一种含有氧化镁一氧化铝，均采用煅烧氧化铝作为骨料。测定了相应的抗热性、热循环前后的抗弯强度、高温抗折强度和蠕变变形。     

Ceramic Castables — Final Stage in the Evolution of Low-Cement Refractory Castables. Part 3

Technological and service characteristics of ceramic castables and low-cement refractory castables (LCRCs) are compared. Unlike LCRCs prepared from dry-ground powders, the ceramic castables contain a nanoparticle phase (5 – 100 nm), which to a significant extent determines their operational properties. The initial mechanical strength of ceramic binders can be increased substantially by adding water-soluble resins to their composition. A way toward developing oxide-carbon ceramic castables is outlined. Compositions for binding agents with enhanced high-temperature strength are developed.     

The main role of silica—Based cement free binders on the microstructural evolution and mechanical behaviour of high alumina castables

One of the major innovations for monolithic refractories in the past decade has been the development of cement-free binders, no-cement castables (NCCs). NCCs with colloidal silica suspensions as binders are extended at industrial scale. Microsilica-based powder binders are valuable alternative to colloidal silica to avoid installation and transport difficulties.The success of NCCs depends on the high temperature microstructure developed. Phase equilibrium diagrams are a powerful tool for the understanding of such development.This work deals with the study of alumina castables fabricated using both silica gel technologies with the aim of establishing the main factors that determine the high temperature (1300–1400?°C, 30–300?min) microstructure and how it affects the mechanical behaviour. Deformation and fracture are determined by the formation of mullite in the matrix. Reaction kinetics is highly dependent of temperature, time and the alumina - silica relative amount at local level, determined by the composition of the binder.     

Hydration of CAC cement in a castable refractory matrix containing processing additives

A growing demand for refractory castables with a particular behavior has been inducing a continuous technological evolution, where one of the most important aspects, is an in-depth knowledge of hydraulic binders. These materials greatly influence the rheological properties and mechanical strength evolution of castables, defining their workability range and demolding time, respectively. The hydration process of hydraulic binders is influenced by the presence of matrix and additives (dispersants and accelerators), which affect the setting and demolding time of shaped bodies. In this work, the influence of these variables on the hydration process of calcium aluminate cement was studied by means of temperature measurements, oscillatory rheometry and normal force measurement. These techniques were able to evaluate the setting behavior of different binders, either in plain water or in matrix-representative suspensions. In both cases, the dispersants presented a retarding effect on the hydration process, which was more significant for citric acid and diammonium citrate. The combination of these additives with an accelerator (Li₂CO₃) was shown to be an efficient tool to control the setting time of castables.     

Does a tiny amount of dispersant make any change to refractory castable properties?

A growing demand for refractory castables with specific behaviors has given rise to a continuous technological evolution, mainly due to the broad knowledge of hydraulic binders available nowadays. The high alumina cements remain as the most important hydraulic binders for castables. Nevertheless, calcium aluminate bound castables still show a characteristic drop of strength at intermediate temperatures, which could also be affected by the castable chemical additive. Thus, this paper aims to highlight the influence of dispersants on the refractory castable properties with the firing temperature. It was noticed that the hydrates formed during the curing process of castable depends on the dispersing additive used. The FS60, a polycarboxylate ether, induced the AH₃ formation and its decomposition resulted in a more stable hydrate (AH), which increased the splitting strength with the thermal treatment temperature. At a high temperature, the CA₂ and CA₆ formation is also favored in the presence of this additive. However, it did not bring benefits to the castables creep behavior, resulting in a less tough structure.     

陶瓷废弃物的资源化研究

以废瓷砖为耐火骨料,叶腊石为细粉,硅微粉、铝酸钙水泥为结合剂,研制了具有耐酸碱特性的浇注料。结果表明,该浇注料完全能够满足水泥窑、垃圾焚烧炉等中温窑炉(1200℃)恶劣气氛的需要,且使用寿命在五年以上。     

Nano-bonded refractory castables

Calcium aluminate cement (CAC) contents higher than 3 wt% in refractory castables can have some drawbacks in the various processing steps (mainly drying) and also in their refractoriness when in contact with SiO₂. The use of colloidal silica as an alternative binder has been studied by many researchers in recent years and recently reports have also explored the use of colloidal alumina for the same purpose. This article reviews the recent developments in nano-bonded refractory castables focusing on the use of colloidal silica or alumina. In the first part of the paper, a comparison of different binding systems for refractory castables is shown. The benefits of replacing CAC or hydratable alumina by colloidal binders are discussed. In the second part, the advantages of colloidal silica/alumina as a refractory binder are highlighted. Meanwhile, the characterization techniques and functional mechanisms of these binders are presented in order to understand the behavior of these systems. Finally, in the last section, the challenges for suitable use of colloidal binders are discussed and the future direction of nano-structured refractory castables is outlined.     

大强度脱硫搅拌器用耐火浇注料的改进

针对大强度脱硫搅拌器用耐火浇注料工作衬损坏严重,搅拌混合性能下降快的问题,选择普通电熔莫来石、烧结锆莫来石为主要原料,CA-80水泥和α-Al2O3微粉、ρ-Al2O3微粉、SiO2微粉为复合结合剂,通过浇注料配方设计、性能检测、显微结构分析、工业试验、实际应用,完成了性能优良的大强度WG-3Y搅拌器用耐火浇注料的改进,在200 t铁水罐搅拌脱硫实际应用中获得高于425次的平均使用寿命。     

New refractory concretes and binding systems: Basic trends of development, production, and use of refractories in the XXIst century. Part I. Trends of development, binding systems

General trends in the development, production, and service of refractories are considered. The share of refractories used in ferrous metallurgy amounts to 60–70%, which means that the predominant trend is determined by the requirements imposed on the refractories used in the steel industry. The proportion of unshaped refractories in the total production will inevitably grow. The basic problem in this field is the improvement of their matrix (disperse) phase, i.e., the binding system. The main types of refractory binders, of which highly concentrated ceramic binding suspensions (HCBS) are the most interesting, are considered. In contrast to natural ceramic binders (clays) HCBS are artificial systems that can be obtained on the basis of many refractory materials. The priority aspect in the creation of new refractory concretes (castables) and binders is described. The first artificial ceramic binders and cement-free refractory concretes based on them were created and installed by the author at the end of the 60s, and in the 70s he suggested many types of ceramic castables, including superlow-cement ones. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 2, pp. 4–13, February, 1998.     

Materials based on highly concentrated ceramic binding suspensions (HCBS). The effect of heat treatment temperature on the strength properties of siliceous ceramic castables

Mechanical properties of siliceous ceramic castables shaped by vibration and static pressing with binders of quartz sand HCBS (pure and with a 5% additive of refractory clay) are studied. Other conditions being equal the porosity and the strength of the materials is affected by the content of the binder (varied from 10 to 33%). Ceramic castables heat treated at 1200 — 300°C exhibit a compressive strength of 50 –60 MPa at a porosity of 12–16%. The effect of the porosity on the strength of the materials is analyzed.     

Novel drying additives and their evaluation for self-flowing refractory castables

The drying step of dense refractory castables containing hydraulic binders is a critical process, which usually requires using slow heating rates due to the high explosion trend of such materials during their first thermal treatment. Thus, this work investigated the performance of alternative additives to induce faster and safer drying of self-flowing high-alumina refractory castables bonded with calcium aluminate cement (CAC) or hydratable alumina (HA). The following materials were analyzed for this purpose: polymeric fibers, a permeability enhancing compound (RefPac MIPORE 20) and an organic additive (aluminum salt of 2-hydroxypropanoic acid). The drying behavior and explosion resistance of the cured samples were evaluated when subjecting the prepared castables to heating rates of 2, 5 or 20 °C/min and the obtained data were then correlated to the potential of the drying agents to improve the permeability and mechanical strength level of the refractories at different temperatures. The collected results attested that the selected additives were more efficient in optimizing the drying behavior of the CAC-bonded compositions, whereas the HA-containing castables performed better when the aluminum-based salt was blended with a small amount of CAC (0.5 wt%), which changed the binders hydration reaction sequence and optimized the permeability level of the resulting microstructure. Consequently, some of the designed compositions evaluated in this work showed improved drying behavior and no explosion was observed even during the tests carried out under a high heating rate (20 °C/min).