碱铝硅酸盐玻璃化学强化关键影响因素概述

化学强化是一种玻璃机械强度增强方法,适用于异型、超薄、高碱、高膨胀玻璃增强,因新型超薄显示产品的屏幕保护玻璃发展需要,化学强化技术重新在碱铝硅酸盐玻璃品种掀起研究热潮。本文对化学强化本质及铝硅酸盐玻璃在屏幕保护玻璃应用进行了回顾,基于玻璃化学强化的高CS、DOL和低CT诉求,归纳总结了关键影响因素,第1,碱铝硅酸盐玻璃的成分及结构是基础,氧化铝有利玻璃网络孔隙增大创造交换通道,氧化钠或氧化锂是离子交换关键物质;第2,对于玻璃组成和结构设计,要求玻璃网络键合度R=O/Si或O/(Si+Al)满足2.15~2.40,碱金属氧化物质量分数大于13%且膨胀系数大于6×10^-6/℃;第3,在化学强化工艺方面,化学强化温度决定离子扩散系数,化学强化时间决定DOL,一步法仅能获得相对较大的CS,而DOL不很理想,只有两种离子参与交换的二步法才有利于CS和DOL同步提高。     

某羟硅铍石矿中浮选富集含铍矿物的试验研究

新疆某羟硅铍石矿BeO品位0.47%,脉石矿物主要是石英、长石、云母等硅酸盐类矿物。为回收利用其中的铍矿物,采用浮选的方法对其进行试验研究。最终在磨矿细度-0.074 mm粒级占90%,调整剂氟化钠用量400 g/t、碳酸钠用量1 500 g/t、硫化钠用量2 000 g/t、六偏磷酸钠用量50 g/t,捕收剂油酸900 g/t+GYB 100 g/t的条件下,进行了一次粗选、一次扫选、四次精选的闭路浮选试验,可获得BeO品位8.31%、回收率84.56%的铍精矿。该羟硅铍石的浮选富集程度较好,可为同类型矿石的开发提供依据。     

Mg-bearing quartz solid solutions as structural intermediates between low and high quartz

Glass powder samples of cordierite composition (doped with 8 mol% TiO₂) were heat-treated to produce a series of increasingly SiO₂-enriched Mg-bearing quartz solid solutions (Qss). The obtained materials were then analyzed by X-ray diffraction: Rietveld structural refinements revealed that Mg-bearing Qss phases possess trigonal symmetry and a compositionally dependent intermediate structural arrangement between those of low and high quartz. High-temperature diffraction measurements were performed up to 700°C to characterize the thermal expansion behavior of the crystals. At SiO₂-rich compositions, a reversible high-to-intermediate inversion of the quartz structure is observed, which shifts with increasing stuffing to lower temperatures than the conventional 573°C for pure quartz. Similarities and differences to the better-established Li-bearing Qss are discussed in the text.     

Thermal behaviour and phases evolution during the sintering of porous inorganic membranes

Anorthite-based highly porous membranes were successfully produced using calcined oyster shell to enhance the pore network. The calcined oyster shells produce CaO responsible for the crystallisation of gehlenite and anorthite at relatively low temperature. While the crystallisation produced nano and meso size of intergranular pores, vitrification of feldspar is responsible for development of the capillary porosities. The increasing sintering temperature from 1200 °C to 1300 °C implies the increase in average pores radius from 1.2 μm to 14.3 μm due to the formation of spherical pores from vitrification. The combination of different class of porosities in the matrices results in the interconnection with improvement of the permeability of the porous network. Porosity, permeability and chemical stability were improved with 20 wt.% of calcined oyster shell addition allowing the possible development of high strength porous network which is promising for the membranes support and other applications including liquid separation as well as liquid filtration where high pressure is used.     

Synthesis of hexacelsian barium aluminosilicate by film boiling chemical vapour process

An original oxide/oxide ceramic-matrix composite containing mullite-based fibers and a barium aluminosilicate matrix has been synthesized by the film boiling chemical vapour infiltration process. Alkoxides were used as liquid precursors for aluminum, silicon and barium oxides. The structure and microstructure of the oxide matrix were characterized by Scanning Electron Microscopy, Energy Dispersive Spectroscopy and X-ray diffraction. Apart from small residual mullite and amorphous phase amounts, the oxide matrix is composed of the hexacelsian phase, conferring to the material interesting perspectives for high-temperature electromagnetic and structural applications.     

ZnO·Al2O3·nSiO2玻璃抗裂纹萌生能力反常演化的结构起源探索

为探究ZnO·Al₂O₃·nSiO₂玻璃抗裂纹萌生能力(C_R)随SiO₂含量变化的演化规律,制备了一系列不同n值(n=2,2.35,2.5,2.65,3,3.5)的样品。基于C_R和结构表征发现,C_R随着n的增加呈先增大后减小的反常演化,并于n=2.5时出现极值(31.1 N)。这是源于随着n增大:(1)原子堆积份数逐渐减小,可致密化体积逐渐增加,从而导致C_R逐步提高;(2)Al—O多面体结构单元含量逐步减少,导致C_R逐步下降;(3)考虑到相界面对裂纹生长的强阻挡能力,中程异构分相(富Al和富Si相)致相界面数量呈先增多后减少的变化趋势,导致C_R产生类似的非单调演化。上述三个因素的竞争和协同作用是该体系中C_R呈反常演化的结构起源,但考虑到极值点附近较小的组分变化,中程异构致相界面数量随n增加呈现的非单调演变才应是C_R呈反常演化的主要结构根源。     

钾/钠离子对水热合成铯榴石结构的影响

水热合成铯榴石能低温、晶格固化放射性废物¹³⁷Cs，但在放射性废物中Cs⁺通常与同族的K⁺/Na⁺共存，两者可能会对水热合成铯榴石组成和结构产生影响。基于此，参考铯榴石化学计量组成CsAlSi₂O₆，首先利用偏高岭土、纳米二氧化硅和CsOH•H₂O为原料水热合成了铯榴石。然后分别以不同摩尔质量的KOH或NaOH取代CsOH•H₂O，研究了K⁺/Na⁺对水热合成产物组成和结构的影响。结果表明，铯榴石水热晶化温度相对较低，产物微观下呈多晶微球态；K⁺与Cs⁺共存时，体系水热产物主要为铯榴石微球，微球尺寸随K⁺掺入比例的提高而增加，但K⁺主要存在于晶化程度较低的钾铝硅酸盐水合物中，并未参与铯榴石形成；Na⁺与Cs⁺共存时，体系水热产物主要由铯榴石和方沸石(NaAlSi₂O₆•H₂O)组成，Cs⁺和Na⁺各自存在于铯榴石或方沸石结构中。铯榴石相对较低的水热晶化温度及其结构中Cs⁺不能迁移和进行离子交换的特性，使得水热条件下K⁺/Na⁺不能进入先形成的铯榴石结构中的碱金属离子位点。尽管如此，K⁺或Na⁺的存在可降低铯榴石的水热晶化温度、促进铯榴石晶粒生长，且当K⁺或Na⁺与Cs⁺共存时，Cs⁺仍优先进入并稳定固化于铯榴石晶体结构中。     

氧化铝生产过程中结疤的生成及防治技术的探索

探讨了碱法生产氧化铝过程中结疤的生成机理和危害以及传统处理方法的弊端,结合中国铝业山东分公司第二氧化铝厂生产物料的结疤状况,对预脱硅工艺预防管道化溶出器结疤进行试验和研究,得出了技术控制条件;将新型化学阻垢剂应用在管式降膜蒸发器,减少了蒸发器结疤速度,延长了蒸发器酸洗周期;将永磁防垢装置应用在精液管道上,减少精液结疤,延长精液降温板式换热器的清洗周期,同时预期解决结疤影响流量计计量准确问题;通过对几种防治结疤的技术在预防氧化铝生产结疤生成方面的实际应用效果展开综合论述,总结并提出了几种切实可行的防治或减缓结疤的途径。     

新型螯合剂对一水硬铝石和铝硅酸盐矿物浮选行为的研究

合成了含有羧基和肟基的新型螯合捕收剂HCMT并研究其对一水硬铝石、高岭石和伊利石的浮选行为。单矿物浮选试验表明,该捕收剂对一水硬铝石、铝硅酸盐矿物的捕收能力差别较大,能有效分离一水硬铝石与铝硅酸盐矿物。通过动电位、红外光谱和电镜扫描(SEM)等研究了捕收剂对矿物的吸附机理,结果表明捕收剂在一水硬铝石表面可能是通过COOH、-NHOH与Al-O形成双环螯合物的化学吸附,而在高岭石、伊利石表面主要是物理吸附。     

Dissolution and Separation of Aluminum and Aluminosilicates

Selection of an aluminum alloy for target cladding affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the dissolver, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. Aluminosilicate dissolution presents challenges in a number of different areas, including metals extraction from minerals, flyash treatment, and separations from aluminum alloys. We present experimental work that attempts to maximize dissolution of aluminum metal in caustic, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as a function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. These data have been compared with published calculations of aluminum phase diagrams. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.