基于电石渣的硬硅钙石晶须的制备与表征

利用水热合成工艺,以电石渣作钙源合成了硬硅钙石晶须.用HCl对电石渣进行酸洗除杂,采用控制电石渣浆pH值,Ca(OH)2选择性溶解的方法去除电石渣中的其它杂质.采用ICP、XRD、SEM和DSC-TG分析了电石渣酸洗后的杂质含量及产品的晶相组成、微观形貌和耐温性.结果表明:控制pH值让电石渣中的化学组分选择性溶出,可使电石渣得以净化,成为制备硬硅钙石晶须的钙源;不同酸洗pH值、水热合成温度及保温时间对电石渣钙回收率、杂质去除率及合成的硬硅钙石晶须形貌具有很大的影响.比较适宜的制备条件是:电石渣酸洗pH=8、水热合成工艺参数220 ℃保温20 h.制备出的硬硅钙石晶须长径比为100～400,最高使用温度可达1000 ℃.     

A composite thermal insulator based on xonotlite and perlite

A low cost thermal insulating material can be produced by compounding an active xonotlite slurry, fired-perlite, HOMO PAN fibers and glass fibers. The maximum service temperature of the product is 800℃; linear shrinkage after 800℃×16 h firing is 0.9%; the cold crushing strength is 1.56 MPa; the flexural strength at ambient temperature is 0.81 MPa; the thermal conductivity at ambient temperature (25℃) is 0.056 and 0.128 W/(m·K) at 800℃. The production cost of such a composite is only 1/3 of that of the normal xonotlite thermal insulators. It can substitute the normal xonotlite thermal insulators on most occasions with a similar cost to that of normal perlite products.     

C2S对硬硅钙石型硅酸钙保温材料质量影响

研究了以天然石灰和天然粉石英为基本原料，添加了2CaO,SiO2对合成硬硅钙石型硅酸钙保温材料的影响，结果表明，随着2CaO,SiO2加入量的逐渐增多，硬硅钙石型硅酸钙保温材料的烘干收缩率逐渐降低，当添加量由0上升到5％时，制品的烘干收缩率由2．19％降低到0．92％，制品由不合格变为合格；烘干收缩率降低的原因是2CaO.SiO2的加入促进了二次粒子形成。     

激光脉冲法测量硬硅钙石绝热材料热扩散率

本文采用非线性参数估计方法来确定硬硅钙石型微孔硅酸钙绝热材料的热扩散率.首先将绝热材料夹在两个金属片之间制成夹层结构试样,采用激光脉冲法测量试样背面温升;然后通过理论温升曲线与实验测得的温升曲线的拟合,来估计绝热材料的热扩散率.采用非线性参数估计可同时估计出热扩散率、散热系数以及试样吸收的能量.通过实验确定出进行热扩散率测量的绝热材料最佳厚度为1.6～1.9mm;由试样厚度精度和接触热阻所引起的测量误差在5.8%以内.     

FORMATION OF MICRO-POROUS SPHERICAL PARTICLES OF CALCIUM SILICATE （XONOTLITE）IN DYNAMIC HYDROTHERMAL PROCESS

Stiming during hydrothermal synthesis plays an important role in the formation of porous spherical xonotlite particles.The size of spherical particles formed during dynamic hydrothermal process is related to the size of minimum vortices in the reaction slurry,which is determined by stirring speed.The kinetics of growth of xonotlite particless is de-termined by measuring the apparent viscosity of the reactant slurry at various reaction time and reaction temperatures.It is found that the growth of particles follows the contracting-volume equation.and the activation energies for nucleation and growth are 104 and 123 kJ-mol,respectively.     

制备条件对硅酸钙复合纳米孔超级绝热材料热导率的影响

为解决SiO2气凝胶质脆和硬硅钙石热导率偏高的问题,以正硅酸乙酯为硅源采用溶胶-凝胶法制备SiO2气凝胶先驱体,而后将其与硬硅钙石复合经超临界干燥制备了硅酸钙复合纳米孔超级绝热材料.采用瞬时热带法测试样品常温下1.01×105～1×10-2Pa范围内的热导率,研究了制备条件对复合材料热导率的影响.结果表明,复合材料热导率随硬硅钙石体积质量的减小以及复合增重率的增加而降低,但随气凝胶体积质量的增大先降低后升高.     

Effect of Al~(3+) on Tobermorite Crystallinity

The difference betWeen the systems of CaO-Sio,-H,o and CaO - S iO, -Al(oH), -H,o, was studie d,esPecially the effect ofAl3' on the crystallinity oftobermorite was focussed. As a result, in the system ofCaO-Sio,-H,o, tobermorite formed early, howeveY, with reaction tdrie forward, tobermorite was replaced byxonotlite. So far as CaO-SiO,-Al(OH),-H,O was concemed, hydrothermal reaction was carried out under thesaJne condition as CaO-Sio,-H,o to study the morphological changes oftobermorite crystals. It was found thatAls+ accelerated the crystal growth oftobermorite to some extent and was in favor ofplaty crystals. Moreovef,with the Al3+ contCllt increasing in the staning matCrial, the morphology of tobermoritC did not change mag-niflcentiy but platy crystals became more and more eminent. As soon as the Al,O, content was over 15.6%,synthetic mineral greatly changed in strUctUre and tUmed into hibschite different from l. l nm tobermorite. Ob-viously xonotlite was not aPt to form in the presence of Al3+.     

利用电石渣制备硬硅钙石活性料浆的初步研究

利用动态水热合成工艺,用电石渣作钙质原料合成了硬硅钙石活性料浆。采用XRD和SEM对合成的硬硅钙石料浆结构和形貌进行了检测及表征。结果表明,煅烧后的电石渣可以制备出纯度较高的,毛栗状球形"二次粒子"明显,且数量多直径大的硬硅钙石活性料浆。研究表明,制备硬硅钙石为电石渣二次回收利用提供了一条有效的途径。     

Evaluation of phases in a hydrothermally treated CaO-SiO2-H2O system

The evolution of hydration products with reaction time in a hydrothermally cured CaO-SiO₂-H₂O system, when using quartz of different fineness, was investigated by means of thermal, X-ray diffraction and wet chemical techniques. A combination of second derivative differential thermal-, first derivative thermogravimetric- and the equivalent differential thermal- and thermogravimetric curves provided more critical information about the nature of phases formed than X-ray diffraction alone. Phenomena including overlapping dehydration reactions and interactions of phases during the thermal experiment are discussed and illustrated by examples. This revised version was published online in July 2006 with corrections to the Cover Date.     

TBX 多孔陶粒滤料制备及废水吸附除磷试验研究

提供微碱性氛围和足够的钙离子浓度是实现高效吸附除磷的重要条件。以白色硅酸钙水泥、硬硅钙石、粉煤灰、黏土和氧化钙等为主要原料, 经水热反应和高温蒸汽养护制备了TBX 多孔陶粒滤料。通过考察试验材料的钙离子浸出速度和浸出液 pH 值变化过程, 确定了高效吸磷滤料的制备工艺。应用制备滤料处理低浓度含磷废水的试验结果显示:在投加量质量分数为 1% , 磷酸盐溶液浓度为10 mg/ L, 吸附 2 小时后, 残 留液磷含量可达0.2mg/L以下, 远低于城镇污水处理厂综合排放一级 A 标准。由于高效吸附除磷特性和低廉造价, 在城市污水除磷和富营养化水体修复领域, TBX 多孔陶粒滤料将有着 良好的工程应用前景。