Effect of sintering temperature on the microstructure and properties of foamed glass-ceramics prepared from high-titanium blast furnace slag and waste glass

Foamed glass-ceramics were prepared via a single-step sintering method using high-titanium blast furnace slag and waste glass as the main raw materials The influence of sintering temperature(900–1060℃) on the microstructure and properties of foamed glass-ceramics was studied. The results show that the crystal shape changed from grainy to rod-shaped and finally turned to multiple shapes as the sintering temperature was increased from 900 to 1060℃. With increasing sintering temperature, the average pore size of the foamed glass-ceramics increased and subsequently decreased. By contrast, the compressive strength and the bulk density decreased and subsequently increased. An excessively high temperature, however, induced the coalescence of pores and decreased the compressive strength. The optimal properties, including the highest compressive strength(16.64 MPa) among the investigated samples and a relatively low bulk density(0.83 g/cm^3), were attained in the case of the foamed glass-ceramics sintered at 1000℃.

Influence of aluminium nitride as a foaming agent on the preparation of foam glass-ceramics from high-titanium blast furnace slag

To effectively reuse high-titanium blast furnace slag （TS）, foam glass-ceramics were successfully prepared by powder sintering at 1000℃. TS and waste glass were used as the main raw materials, aluminium nitride （AIN） as the foaming agent, and borax as the fluxing agent. The influence of the amount of A1N added （lwt%-5wt%） on the crystalline phases, microstructure, and properties of the produced foam glass-ceramics was studied. The results showed that the main crystal phases were perovskite, diopside, and augite. With increasing A1N content, a transformation from diopside to augite occurred and the crystallinity of the pyroxene phases slightly decreased. Initially, the aver- age pore size and porosity of the foam glass-ceramics increased and subsequently decreased; similarly, their bulk density and compressive strength decreased and subsequently increased. The optimal properties were obtained when the foam glass-ceramics were prepared by adding 4wt% AIN.

Influence of CeO_2 addition on the preparation of foamed glass-ceramics from high-titanium blast furnace slag

Foamed glass-ceramics doped with cerium oxide（CeO_2）were successfully prepared from high-titanium blast furnace slag by one-step sintering.The influence of CeO_2 addition（1.5wt%–3.5wt%）on the crystalline phases,microstructure,and properties of foamed glass-ceramics was studied.Results show that CeO_2 improves the stability of the glass phase and changes the two-dimensional crystallization mechanism into three-dimensional one.XRD analysis indicates the presence of Ca（Mg,Fe）Si_2O_6 and Ca（Ti,Mg,Al）（Si,Al）_2O_（6 ）in all sintered samples.Added with CeO_2,Ti CeO_4 precipitates,and crystallinity increases,leading to increased thickness of pore walls and uniform pores.The comprehensive properties of foamed glass-ceramics are better than that of samples without CeO_2.In particular,the sample added with a suitable amount of CeO_2（2.5wt%）exhibits bulk density that is similar to and compressive strength（14.9 MPa）that is more than twice of foamed glass-ceramics without CeO_2.

Volume and Surface Nucleation of Crystals in Glass Based on Blast-Furnace Slag

Using differential thermal analysis, X-ray phase analysis, electron microscopy, and optical microscopy, the nucleation of crystals in glass obtained by blending metallurgical slag with silicon dioxide has been studied. The type of crystallization (homogeneous or heterogeneous, volume or surface) is revealed for each of nine compositions of synthesized glass. It is shown that the first crystalline phase in a volume crystallizing glass is perovskite (CaO·TiO2);in this phase a nucleation of the main phase occurs: melilite (solid solution of gehlenite 2CaO·Al2O3·SiO2 in akermanite 2CaO·MgO·2SiO2). The fundamental characteristics of homogeneous (for a catalizing phase, perovskite) and heterogeneous (for a catalyzed phase, melilite) of crystallization are determined: the steady state nucleation rate Ist, time of unsteady state nucleation τ, crystal growth rate U, and activation energy of frictional flow. The temperature dependences of Ist, τ, and U are obtained. The kinetics of the crystallization of glass is studied and the rates of the surface crystal growth are determined in the glass of nine compositions. The influence of grinding the particles of the original glass on the sequence of deposition of the crystalline phases was studied. Practical recommendations are presented for the use of blast-furnace slag as a raw material for the synthesis of glass and their further utilization.

Effect of Fe_2O_3 on the crystallization behavior of glass-ceramics produced from naturally cooled yellow phosphorus furnace slag

CaO–Al2O3–SiO2(CAS) glass-ceramics were prepared via a melting method using naturally cooled yellow phosphorus furnace slag as the main raw material. The effects of the addition of Fe2O3on the crystallization behavior and properties of the prepared glass-ceramics were studied by differential thermal analysis, X-ray diffraction, and scanning electron microscopy. The crystallization activation energy was calculated using the modified Johnson–Mehl–Avrami equation. The results show that the intrinsic nucleating agent in the yellow phosphorus furnace slag could effectively promote the crystallization of CAS. The crystallization activation energy first increased and then decreased with increasing amount of added Fe2O3. At 4wt% of added Fe2O3, the crystallization activation energy reached a maximum of 676.374 kJ·mol−1. The type of the main crystalline phase did not change with the amount of added Fe2O3. The primary and secondary crystalline phases were identified as wollastonite (CaSiO3) and hedenbergite (CaFe(Si2O6)), respectively. © 2017, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

Effect of Glass Powder on Chloride Ion Transport and Alkali-aggregate Reaction Expansion of Lightweight Aggregate Concrete

The effects of glass powder on the strength development, chloride permeability and potential alkali-aggregate reaction expansion of lightweight aggregate concrete were investigated. Ground blast furnace slag, coal fly ash and silica fume were used as reference materials. The re- placement of cement with 25% glass powder slightly decreases the strengthes at ？ and 28 d, but shows no effect on 90 d＇s. Silica fume is very effective in improving both the strength and chloride penetration resistance, while ground glass powder is much more effective than blast furnace slag and fly ash in improving chloride penetration resistance of the concrete. When expanded shale or clay is used as coarse aggregate, the concrete containing glass powder does not exhibit deleterious expansion even if alkali-reactive sand is used as fine aggregate of the concrete.

Mechanism of phase separation in BFS (blast furnace slag) glass phase

XRD,TEM,ED,and NMR analyzed four types of blast furnace slags (BFS) with different structures in this paper. The composition requirement for phase separation in BFS glass phase was then put forward,that is the composition of slag locates in the coexisting phase region of melilite and any silicate mineral with Q0 units. The special structure of melilite units,a 5-membered ring with high degree of polymerization (DOP),plays a key role in the formation of phase separation. In BFS system,one with chemical composition of larger ratio of (CaO + MgO/(SiO2 + Al2O3) would be more promising to meet the requirement for phase separation.

高炉渣和低碳铬铁合金渣协同制备微晶玻璃

这是一篇矿物材料领域的论文。为对大宗工业固废进行高值化利用和无害化处理,以包钢高炉渣、低碳铬铁合金渣和石英砂为原料熔融法制备CaO-MgO-Al_(2)O_(3)-SiO_(2)-Cr_(2)O_(3)体系微晶玻璃。并通过差热分析(DSC)、X射线衍射(XRD)、扫描电子显微镜(SEM)等分析手段探究较优原料配比。结果表明:当高炉渣、低碳铬铁合金渣、石英砂质量比例为60∶40∶31时,制得微晶玻璃的晶相为透辉石和绿辉石,此时微晶玻璃性能较优,抗折强度达到126.25 MPa,晶化度达到89.19%,显微结构较理想。较优原料配比条件下制备的微晶玻璃满足国家A类装饰装修材料IRa≤1.0和Iγ≤1.3的要求,且微晶玻璃中重金属铬的浸出浓度符合国家标准,表明采用高炉渣和低碳铬铁合金渣制备微晶玻璃具有可行性。

高炉渣制备微晶玻璃的研究

以济南钢铁厂的高炉渣为主要原料,辅以其它化学试剂,制备了微晶玻璃,对高炉渣微晶玻璃的配方,核化和晶化温度进行了研究,并用SEM,DTA,XRD分析表征了制得的微晶玻璃样品的微观结构和结晶情况.

CaF_2对自然冷却黄磷炉渣微晶玻璃析晶行为影响

借助DTA、SEM、XRD等分析测试手段,研究氟化钙晶核剂含量对自然冷却态黄磷炉渣微晶玻璃析晶及其性能的影响规律。利用修正后的JMA方程计算微晶玻璃的析晶活化能E及晶体生长指数n动力学参数。结果表明:Ca F2晶核剂的引入可以促进微晶玻璃的析晶,改变析晶峰温度和活化能。随着Ca F2进一步添加并不能改变主晶相(硅灰石)类型,而是生成新的Ca F2晶相,同时改晶粒尺寸。当添加2.5wt%Ca F2时,微晶玻璃的析晶动力学参数最优,产品性能优异,可以作为优良的建筑装饰材料。

矿渣微晶玻璃产品的研究与开发

对矿渣微晶玻璃的开发与研究情况进行了评述 ,重点介绍了矿渣微晶玻璃生产线的研究与发展成果 。

中钛型含钛高炉渣制微晶玻璃及其性能研究

以中钛型含钛高炉渣为主原料制备微晶玻璃,利用渣中的TiO_2作晶核剂。采用差示扫描量热法(DSC)、X射线衍射(XRD)和扫描电子显微镜(SEM)等分析技术研究了含钛高炉渣用量的变化对基础玻璃晶化、微晶玻璃性能的影响。结果表明,渣中适量的TiO_2对玻璃晶化有较好的促进作用。渣用量较低时制得的微晶玻璃的主晶相为硅灰石,但当渣用量超过70%时,主晶相发生变化,变为钙铝黄长石等长石类矿相。中钛型含钛高炉渣用量为63%左右时,制得的微晶玻璃晶相含量合适,性能最好。此时采用的热处理制度为:核化温度720℃,保温1h,晶化温度945℃,保温2h,制得的微晶玻璃抗弯强度为121.68 MPa,显微硬度为7.81GPa。

利用新疆高炉渣制备微晶玻璃的研究

以新疆高炉渣为原料,辅以少量钾长石为助熔剂,采用直接烧结法制备高炉渣微晶玻璃。利用DSC、XRD及SEM等测试手段,对微晶玻璃热处理制度、物相组成及显微结构进行了研究并探讨了粉体粒度大小和钾长石含量对微晶玻璃性能的影响。结果表明,微晶玻璃主晶相为钙镁黄长石,晶体呈颗粒状。样品的各项性能和析晶能力随粉体粒度减小而增大,钾长石对微晶玻璃析晶能力有一定促进作用,但随着粉体粒度的减小而逐渐减弱。钾长石含量过高时,导致玻璃内液相过多而影响制品的力学性能。由球磨60 h的粉体添加5wt%钾长石制备的样品各项性能最好,密度为2.81 g/cm3,抗弯强度为87.76 MPa,显微硬度为5.60 GPa。

直接烧结法制备高炉渣微晶玻璃的研究

介绍了以安阳钢铁集团公司高炉渣为主要原料,采用直接烧结法制备炉渣微晶玻璃.用DSC,XRD,SEM研究了微晶玻璃的热处理制度及微观结构,确定其主晶相为钙铝黄长石,晶粒尺寸约为1μm,抗弯强度为72MPa.实验表明,直接烧结法是一种较为简单的制备微晶玻璃的方法,制备的炉渣微晶玻璃性能可与传统工艺相比,且性能优于其他建材.高炉渣的利用率可达90%以上.

矿渣微晶泡沫玻璃核化及晶化制度的优化

目的利用高炉矿渣、粉煤灰和废玻璃为原材料制备矿渣微晶泡沫玻璃,在确定微晶泡沫玻璃配方范围的基础上,对制备微晶泡沫玻璃的核化和晶化工艺参数进行了优化,使之具有轻质高强的优良性能.方法采用粉末烧成法工艺和正交试验优化设计的试验手段.结果严格控制核化及晶化工艺参数对制备具有较高抗压强度的矿渣微晶泡沫玻璃是十分必要的.晶化温度对微晶泡沫玻璃抗压强度影响显著,晶化温度不宜过高,否则材料的抗压强度明显下降.结论确定了热处理的优化条件:核化温度为740℃,核化时间为50 min,晶化温度为910℃,晶化时间为40 min.在优化条件下制备的矿渣微晶泡沫玻璃由泡径2～3 mm的气孔、晶体和玻璃相组成,XRD显示主晶相为透辉石;表观密度946kg/m3,抗压强度17.9 MPa,吸水率为0.25%,可代替实心粘土砖作为墙体材料使用.

碳酸钙对缓冷高钛高炉渣制备泡沫微晶玻璃的影响

利用缓冷高钛高炉渣和废玻璃为主要原料,通过发泡和析晶同时进行的“一步法”在980℃烧结制备泡沫微晶玻璃。研究了CaCO3对制备泡沫微晶玻璃的影响。结果表明,CaCO3对发泡和析晶过程都有影响。在不同的CaCO3添加量（1%～5%,质量分数）下,泡沫微晶玻璃的主要晶相类型无明显差异,都以透辉石 Ca（Mg,Al）（Si, Al）2 O6和普通辉石Ca（Mg,Fe,Al）（Si,Al）2 O6为主晶相,以硅辉石 CaSiO3为次晶相；CaCO3添加量由1%增至3%时晶相含量明显增加,而在3%～5%范围内晶相含量增加不大。随着CaCO3含量增加,泡沫微晶玻璃晶体由不规则颗粒状变成针状和短柱状,泡孔孔径减小,气孔率和吸水率减小,体积密度和抗压强度增大,其中当 CaCO3含量为3%时泡沫微晶玻璃的综合性能最佳。

高炉熔渣微晶玻璃的结构与性能研究

高温熔渣具有大量显热与渣体。采用熔融法制备微晶玻璃可以更好地利用其热和渣,达到高效利用的目的。通过高温条件下混熔的方式制备性能稳定的基础玻璃。利用差示扫描量热仪(DSC)确定基础玻璃的热处理工艺制度。结合高分辨透射电子显微镜(TEM)、X射线衍射分析(XRD)、场发射扫描式电子显微镜(FE-SEM)对微晶玻璃的结构进行了研究。研究表明:基础玻璃中氟含量的增加,有利于促进微晶玻璃成核和晶体长大,降低微晶玻璃的形核结晶温度。在低温热处理得到微晶玻璃的主晶相为萤石,高温热处理得到的微晶玻璃析出了霞石和萤石两个微晶相。高炉渣微晶玻璃中,微晶相的出现可有效提高微晶玻璃的力学性能,试样的显微硬度最高可达585.68MPa,抗折强度最高可达126.21 MPa。

烧结温度对高钛高炉渣制备微晶泡沫玻璃的影响

采用高钛高炉渣和废玻璃为主要原料,Ca CO3作为发泡剂,硼砂Na2B4O7·10H2O作为助熔剂,磷酸钠Na3PO4·12H2O作为稳泡剂,通过"一步法"烧结制备了微晶泡沫玻璃。研究了烧结温度对微晶泡沫玻璃的影响,通过SEM及XRD对高钛高炉渣制备微晶泡沫玻璃的显微组织结构和物相进行分析。研究表明:在850~950℃之间,高钛高炉渣内的钙钛矿随烧结温度的增加逐渐分解,与其他物质反应生成透辉石Ca(Mg,Al)(Si,Al)2O6、普通辉石Ca(Mg,Fe,Al)(Si,Al)2O6、Ca(Mg,Fe)(Si,Al)2O6和硅辉石Ca Si O3等晶体。微晶泡沫玻璃的孔径随烧结温度的增加逐渐增大,最后形成大孔和连通孔,同时,孔壁上析出的晶体数量增加,且晶体的形状从颗粒状变成层片状。在烧结温度为900℃时,微晶泡沫玻璃综合性能达到最佳:密度为0.631 2 g/cm3,气孔率为74.5%,吸水率为8.3%,抗压强度为9.09 MPa。

Na_2B_4O_7·5H_2O对用高钛高炉渣制备微晶泡沫玻璃的影响

为更好地利用废弃物高钛高炉渣,以高钛高炉渣和废玻璃为主要原料,硼砂Na2B4O7·5H2O为助熔剂,Al N为发泡剂,通过'一步法',即同步实现发泡和析晶,在1 000℃条件下制备微晶泡沫玻璃。通过对微晶泡沫玻璃进行XRD、SEM检测分析,以及物理、力学性能测试,研究了助熔剂添加量((wt)4%~7%)对微晶泡沫玻璃的物相、微观组织和性能影响。结果表明:助熔剂添加量对微晶泡沫玻璃的物相影响不大,仅为不同辉石类间转变,即由透辉石、钙铁辉石和绿辉石向普通辉石转变;随助熔剂添加量增加,体系软化程度显著增加,孔壁更密实,气孔显著增大,有连通孔形成;微晶泡沫玻璃的气孔率增大,体积密度、抗压强度和导热系数减小;当助熔剂添加量为5%时,微晶泡沫玻璃的综合性能最好。

包钢高炉渣制备微晶玻璃的析晶方式研究

以包钢高炉渣为主要原料,采用熔融法制备CaO-MgO-Al_2O_3-SiO_2系微晶玻璃,通过差热分析(1TA)、X射线衍射(XRD)、扫描电子显微镜(SEM)分析方法,并借助Ozawa方程研究了添加不同数量晶核剂时的析晶方式。研究结果表明:分别加入8%CaF_2、8%TiO_2和4%P_2O_5作晶核剂时,晶化指数n均小于3,析晶方式为表面析晶;当加入晶核剂为8%P_2O_5时,晶化指数n大于3,析晶方式为整体析晶。