Rheological Behavior of Bauxite-Based SiC-Containing Castables

Low cement (LC) and ultra-low cement (ULC) bauxite-SiC castables are important and high performance monolithic refractories and they have been widely used in iron-making and incinerator lining.In this work,rheological behavior of LC and ULC bauxite-based SiC-containing castables has been studied,including the effects of SiC content and cement content on rheological properties of the castables.The results show that with an increase of SiC and Cement contnet,rheological properties of the castables deteriorate.On the other hand,moderate amounts of SiC(4%-8%) and of calcium aluminate cement (2%-4%) have very slight influence on rheological properties (i.e.when the castables are sheared their torque and yield torque only slightly increase with the shearing speed).The rheological characteristics of the castables follow Bingham fluid and always show shear thinning behavior.     

矾土基浇注料基质的流变性

浇注料的流变性在很大程度上受基质流变行为的影响和控制。本工作主要研究了矾土基浇注料基质中的SiO2微粉、Al2O3微粉、水泥的加入量、分散剂以及矾土细粉粒度对基质流变性(粘度、剪切速率和剪切应力)的影响根据研究结果,得出了具有较好流变性的基质组成。     

Preparation and Microstructure of Bauxite-Based Sialon by Reduction Nitridation

The phase composition and microstructure of Sialon prepared from Chinese bauxite have been studied. The use of Si powder is more effective than that of activated carbon for reduction-nitridation. For bauxite specimens with 40～50% Si addition, more than 90% of Sialon may be obtained when nitrided at 1450～1500℃ ; the main crystalline phase is O‘-Sialon ( Z =0.2).     

Zeta Potential and Rheological Behavior of ULC Castables Matrix

Effects of starting materials and four dispersants （ STP, SHP, FDN and FS60 ） on Zeta potential and rheological behavior of alumina based ULC castables matrix were investigated. The results show that： characteristics of silica fume and alumina cements play a very important role in Zeta potential and viscosity of suspensions of the castables matrix; the dispersants STP and SHP can change Zeta potential values of the matrix suspensions remarkably; the four dispersants can effectively improve the rheological properties of matrix suspensions. For the point of lower viscosity of the matrix suspensions, the suitable additions of the three dispersants （ SHP , FDN and FS60 ） are about 0. 2% while that of STP is about 0. 3%.     

Influences of Polycarboxylate Superplasticizers on Rheological Behavior of Low-cement Castables

Influences of different superplasticizers(STP,KSJS70 and LMS-P) on rheological behavior of low-cement castables and the mechanisms were analyzed.The shear stress and viscosity under different shear rates of matrix slurry were determined using a NXS-11A rotary viscometer. Effects of different admixtures on the rheological properties of slurry was analyzed theoretically.Sodium tripolyphosphate and polycarboxylate superplasticizers (KS-JS70 and LMS-P) can improve the fluidity and initial setting time.With STP.the slurry is plastic flow. With KS-JS70 or LMS-P increasing.the slurry changes from plastic flow,pseudoplastic flow to dilatant flow successively. The optimum dosages of STP.KS-JS70 and LMS-P are 0.15%.0.25%and 0.40%.respectively. KS-JS70 and LMS-P can significantly reduce the slurry viscosity and shear stress to improve the workability of construction.Both shear stress and viscosity shall be taken into account for on-site construction.     

Additives to Control the Rheological Properties of Unshaped Castables

Comparative test data are reported for additives (available from domestic and foreign manufacturers) that are commonly used to control the rheological properties of castables. The domestic additives are shown to be effective thinners for refractory castable compositions and provide conditions for adequate water demand of castable mixes not inferior to those of foreign additives. The physicomechanical properties of refractory castables conditioned by domestic superplasticizers are likewise not inferior to foreign analogs except perhaps for the mechanical strength. __________ Translated from Novye Ogneupory, No. 9, pp. 44 – 48, September, 2005.     

耐火浇注料的干燥性能

对浇注料干燥性能的了解是帮助耐火材料生产商优化加热过程的一个重要因素，由此可将在生产过程中替代损毁砖所花费的时间和能源费用降至最低。     

无水泥高铝浇注料的热机械性能

测定了高铝质无水泥自流浇注料的机械性能,并将其结果与相似组成的超低水泥（ULC）浇注料的机械性能做了对比。     

Effect of Water Addition on Rheological Behaviour of Bauxite Based Low-cement Castables

Water addition has direct impact on castables and needs to be under control placement and properties, In this work, two rheological properties, flow resistance and torque viscosity, have been measured against time, with different water addition in the same bauxile-based LC Castable mix. The flow resistance indicates the mobility, whereas the torque viscosity dictates the stability of a castable during installation. It has been observed that with 6.0 wt% water addition, such a mix possesses good vibration castable characteristics; with 6. 5 wt% , it shows good self-flow castable characteristics; and with 7.0wt%, it can be a good pumpable castable, in every case with comparable mechanical properties. While with 7.5wt% water addition, the properties of such castable ared efinitively impaired.     

设计粒度分布的耐火浇注料的渗透性和干燥行为

控制粒度分布可以改变浇注料制品的流变学特性和机械性能。基于PSD设计软件的不同，对浇注料试样进行了渗透性试验和干燥试验，指出控制粒度分布对耐火材料用户而言是调整产品流动性能和机械性能的有效途径。     

含聚丙烯纤维自流浇注料的流变特性和物理性能

自流浇注料是一种特殊类型的浇注料，它可以不用振动进行浇注。本文对在板状氧化铝基低水泥浇注料系统中添加聚丙烯纤维的尺寸和数量进行了研究。纤维添加物通过改变基质的粘度大大减小了系统的自流性。本文就纤维添加物对自流浇注料显气孔率、气孔大小及孔径分布的影响进行了详细的研究。     

丙烯腈-苯乙烯-丙烯酸酯共聚物的流变性能

用毛细管流变仪测试了丙烯腈-苯乙烯-丙烯酸酯（ASA）树脂的表观黏度、黏流活化能、非牛顿指数等流变参数,讨论了剪切速率、剪切应力、温度对ASA的表观黏度的影响,研究了黏流活化能与剪切速率的变化规律。结果表明,随着温度升高, 共聚物的表观黏度下降,非牛顿指数增大;随着剪切速率的增大,树脂的黏流活化能降低;其非牛顿指数n小于1,说明ASA是典型的假塑性流体。     

茂金属聚乙烯流变特性的研究

研究了自制中试茂金属聚乙烯的流变特性，并将流变试验结果用于改进中试茂金属聚乙烯产品熔体破裂使熔体破裂现象基本消失。     

改性聚乙烯醇体系熔体的流变性能

采用HAAKE RHEOCORD－90挤出式毛细管流变仪测定了改性PVA体系的流变性能。结果表明，改性PVA熔体是对剪切速率敏感的假塑性流体，非牛顿指数n较小，熔体偏离牛顿流体的程度较大。在相同温度及剪切速率下，随水含量增加，改性PVA体系的表观粘度下降。改性PVA体系的粘流活化能随剪切速率提高和水含量减少而降低，即温度敏感性降低。     

试样尺寸对高铝质浇注料干燥性状的影响

分析了试样尺寸对超低水泥高铝质浇注料的干燥性状的影响，通过从室温到800℃进行的热重量分析试验所获得的不同尺寸试样的重量损失数据，绘制出了试样的升温曲线和干燥曲线，而且查明了试样的尺寸对产生炸裂也有重大的影响。还论述了包括这些因素在内在工业上的应用。     

干纺氨纶纺丝原液的流变性能

利用RS150L型流变仪研究了干纺氨纶纺丝原液的流变性能。讨论了剪切速率、温度和溶液浓度对纺丝原液流变性能的影响,获得了纺丝原液在不同温度下的非牛顿指数,计算了不同剪切速率下纺丝原液的粘流活化能。进一步建立了干纺氨纶纺丝原液的零切黏度与温度、溶质的质量分数的关系式。     

羟丙基纤维素溶液的流变性能

采用ARES-RFS流变仪测定了羟丙基纤维素溶液的流变性能,考察了温度、溶液浓度、醚化剂量对溶液流变行为的影响,并得到了溶液的非牛顿指数、黏流活化能及结构黏度指数。结果表明:羟丙基纤维素溶液属于假塑性流体,随温度升高、浓度降低、醚化剂用量的增加,该溶液的表观黏度降低,非牛顿指数增大。     

mLLDPE流变与加工特性的研究

主要研究国产mLLDPE加工特性,通过流变试验确定mLLDPE的临界剪切速率范围,并在mLLDPE中加入加工助剂,消除mLLDPE的熔体破裂现象,利用mLLDPE与LDPE共混,增强mLLDPE熔体强度,提高膜泡稳定性。     

氧化铝陶瓷料浆流变性的研究

主要研究了氧化铝料浆的流变性能,确定了分散剂的加入量与料浆浓度的关系,测得氧化铝浓料浆为剪厚型流体,通过对浓悬浮体流变性的研究得到其稳定分散的最佳pH范围是11～12.