微粉对矾土基超低水泥浇注料性能的影响

以高铝矾土熟料为主原料 ,加入 2 %的铝酸钙水泥及总量为 6 %的Al2 O3 微粉和SiO2 微粉 ,配制了矾土基超低水泥浇注料 ,研究了微粉对浇注料的烧结性能、力学性能及热震稳定性的影响。结果表明 :(1 )SiO2 微粉对浇注料的促烧结作用优于Al2 O3 微粉。这是因为与Al2 O3 微粉相比 ,由气相沉积生成的SiO2微粉的粒度小 ,比表面积大 ,活性较高。 (2 )随着SiO2微粉加入量的增加 ,在 1 1 0 0℃和 1 4 0 0℃处理后的常温强度以及在 1 30 0℃和 1 4 0 0℃下的高温抗折强度和抗热震性明显提高。这是由于引入的SiO2 微粉在高温下与Al2 O3 反应生成的针状莫来石穿插进入刚玉骨架 ,起着明显的强化和韧化作用     

Compatibilization of PP/elastomer/microsilica composites with functionalized polyolefins: Effect on microstructure and mechanical properties

The morphology and mechanical properties of polypropylene/elastomer/silica composites were investigated with the aim of improving stiffness and impact resistance. Two different types of silica were tested: Precipitated silica and polymer grade microsilica (silica fume). The composites were compatibilized with commercial polypropylene and polyethylene containing maleic anhydride functionality as a means of controlling their microstructure and ultimately their mechanical properties. Comparisons were made with surface coated silica and hydroxyl-functionalized copolymers prepared with metallocene catalysts. The effect of adding the polymeric compatibilizers was assessed by morphology studies, thermal analysis and mechanical testing. Significant improvements in impact strength were obtained by tailoring the microstructure of polypropylene/elastomer/microsilica composites. With introduction of PP-g-MAH as compatibilizer, stiffness was enhanced simultaneously with impact strength. DSC curves of crystallization provided evidence to support the formation of different microstructures.     

高炉出铁沟用Al2O3-SiC-C浇注料流动性和流动性衰减的研究

通过调整氧化硅微粉加入量和活性氧化铝微粉的类型 ,研究了Al2 O3-SiC -C浇注料的流动性和流动性衰减以及可工作时间的变化。结果表明 :在浇注料流动性相近的情况下 ,随着氧化硅微粉加入量的增加 ,加水量显著降低 ;浇注料的流动性与所引入的活性氧化铝微粉的特性密切相关 ;氧化硅微粉加入量的增加有助于延长浇注料的可工作时间 ;浇注料流动性的衰减呈现出先缓慢后迅速降低直至凝结的特点 ,一般在可工作时间之后迅速凝结     

Preparation and characterisation of self-flowing refractory material containing 971U type microsilica

Abstract

A newer composition of self-flowing low cement brown fused alumina castable containing 971U type microsilica was developed. Optimum flow characteristics were achieved using water addition of 4·6?wt-%. This batch was sintered at different firing temperatures up to 1500°C. To understand the effect of both firing temperatures and corresponding phases, the present castable was characterised in terms of X-ray diffraction, scanning electron microscopy, bulk density (BD), apparent porosity (AP), water absorption (WA), cold crushing strength (CCS) and self-leveling flowability. The results revealed that gradual increase in firing temperature from 1100 through 1500°C caused low AP and WA, and high CCS properties due to the densification of the castable.     

M- S-H formation in MgO-SiO2slurries via wet milling for magnesia based castables

It is believed that the formation of hydration phase, MgO-SiO₂-H₂O (M-S-H), contributes to good workability and reliable comprehensive properties for magnesia based castables. In order to stimulate the formation of M-S-H in magnesia based castables and understand the minimum introduction of microslica amount, wet milling process was used to promote the dissolution of MgO and SiO₂ in this work. The slurry containing different content of microsilica with wet milling technology and the castables with/without wet milling slurry were prepared. The effects of microsilica content on the formation of hydration phases were analyzed by XRD, FT-IR and TG/DSC and the properties of magnesia based castables were evaluated by explosion resistance, CMOR, HMOR and so on. The results showed that the formation of M-S-H was accelerated because of the dissolution of Mg²⁺ and HSiO₃^? in wet milling process. Higher amount of M-S-H led to a tight bonding in the early stage, and a denser structure after firing at high temperature due to the limited formation of brucite and in-situ formation of evenly distributed forsterite phase. In addition, much higher HMOR were obtained when less microsilica was added, attributing to the suppressed formation of low-melting-point liquid. Therefore, 2–3 wt% microsilica addition was recommended in this process.     

SiO2微粉加入量对刚玉质超低水泥浇注料高温性能的影响

研究了SiO2微粉加入量为0、2%、4%、6%和8%时对刚玉质超低水泥浇注料的烧结性能、高温强度及抗热震性能的影响.结果表明随着SiO2微粉加入量的增加,试样的烧结性能和抗热震性得到明显改善,在1400℃时的高温抗折强度也显著提高.讨论认为,试样高温性能提高的主要原因是SiO2微粉与Al2O3反应生成的莫来石穿插或弥散在刚玉颗粒形成的骨架结构的孔隙中起增韧作用.     

高铝矾土-尖晶石钢包砖用结合剂的研究

研究了以硅微粉作结合剂,以四种外加剂在不烧高铝矾土－尖晶石钢包砖中的作用机理;阐明了硅微粉和糊精作复合结合剂时砖体强度和温度之间的关系。生产的不烧砖在平炉钢包渣线上使用,取得了较好效果。     

Hydration mechanism and sintering characteristics of hydratable alumina with microsilica addition

Hydratable alumina is potential for the application in refractory industry as one of Ca-free binders, but it is greatly limited because of the excess hydration of rho-alumina (ρ-Al₂O₃). In this study, hydration mechanism and sintering characteristics of hydratable alumina with different microsilica addition are researched, via the rheological, hydration, and morphological characteristics of ρ-Al₂O₃–SiO₂–H₂O system during aging are analyzed using various techniques. Boehmite (AlOOH) initially appears and increases in content after 1 h aging at the setting temperature of 30 °C and relative humidity of 80%. As the addition of microsilica increases from 0 wt% to 8 wt%, the SiO₂ coating combines with the boehmite gel and efficiently suppresses the hydration reaction, resulting in decrease of relative hydrated densities from 5.42% to 4.27% and increase of zeta potential from −10.1 mV to −21.3 mV. Further, the thus-formed SiO₂-AlOOH gels cover the surface of hydratable alumina particles, connect with each other, and get distributed homogeneously around hydratable alumina particles to harden, thus inhibiting the further hydration. This is reflected by the high-temperature X-ray diffraction and the final sintering microstructures. Overall, these results indicate that the 6 wt% addition of microsilica makes hydratable alumina promising for application as a kind of controlled binders.     

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.     

硅微粉对铝镁系浇注料相组成及性能的影响

利用X射线衍射分析和相图分析,研究了硅微粉对高纯铝镁系浇注料物相组成和不同温度下的物理性能及蠕变性能的影响。