Influence of Al_(2)O_(3)/SiO_(2) Ratio on the Structure and Properties of Na^(+)/K^(+)Ion Exchange Na_(2)O-MgO-Al_(2)O_(3)-SiO_(2) Glasses

In this work,the structure,viscosity and ion-exchange process of Na_(2)O-MgO-Al_(2)O_(3)-SiO_(2) glasses with different Al_(2)O_(3)/SiO_(2) molar ratios were investigated.The results showed that,with increasing Al_(2)O_(3)/SiO_(2) ratio,the simple structural units Q_(1) and Q_(2) transformed into highly aggregated structural units Q_(3) and Q_(4),indicating the increase of polymerization degree of glass network.Meanwhile,the coefficient of thermal expansion decreased from 9.23×10^(-6)℃^(-1) to 8.88×10^(-6)℃^(-1).The characteristic temperatures such as melting,forming,softening and glass transition temperatures increased with the increase of Al_(2)O_(3)/SiO_(2) ratio,while the glasses working temperature range became narrow.The increasing Al_(2)O_(3)/SiO_(2) ratio and prolonging ion-exchange time enhanced the surface compressive stress(CS)and depth of stress layer(DOL).However,the increase of ion exchange temperature increased the DOL and decreased the CS affected by stress relaxation.There was a good linear relationship between stress relaxation and surface compressive stress.Chemical strengthening significantly improved the hardness of glasses,which reached the maximum value of(622.1±10)MPa for sample with Al_(2)O_(3)/SiO_(2) ratio of 0.27 after heat treated at 410℃for 2 h.

Effect of Fe_(2)O_(3)on the Structure,Physical Properties and Crystallization of CaO-Al_(2)O_(3)-SiO_(2)Glass

The calcium aluminosilicate-based glasses(CaO-Al_(2)O_(3)-SiO_(2),CAS)with different Fe_(2)O_(3)content(0.10wt%,0.50wt%,0.90wt%,and 1.30wt%)were prepared by traditional melt-quenching method.The glass network structure,thermal and mechanical properties,and crystallization behavior changes were investigated by nuclear magnetic resonance spectrometer,Fourier-transform infrared spectro-photometer,X-ray diffractometer,differential scanning calorimetry and field emission scanning electron microscope measurements.The change of Q^(n)in glass structures reveals the glass network connectivity decreases due to the increasing content of Fe_(2)O_(3)addition,resulting in the increasing of non-bridging number in glass structure.The glass densities slightly rise from 2.644 to 2.681 g/cm^(3),while Vickers’s hardness increases at first,from 6.469 to 6.901 GPa,then slightly drops to 6.745 GPa,with Fe_(2)O_(3)content increase.There is almost no thermal expansion coefficient change from different Fe_(2)O_(3)content.The glass transmittance in visible range gradually decreases with higher Fe_(2)O_(3)content,resulting from the strong absorption of Fe^(2+)and Fe^(3+)ions.The calculated activation energy from thermal analysis results first decreases from 282.70 to 231.18 kJ/mol,and then increases to 244.02 kJ/mol,with the Fe_(2)O_(3)content increasing from 0.10wt%to 1.30wt%.Meanwhile,the maximum Avrami constant of 2.33 means the CAS glasses exhibit two-dimensional crystallization.All of the CAS glass-ceramics samples contain main crystal phase of anorthite,the microstructure appears lamellar and columnar crystals.

Properties of Aluminosilicate Glasses Prepared by Red Mud with Various [Al2O3]/[CaO] Mass Ratios

By introducing other oxide materials（SiO_2, Al_2O_3, CaO） into the red mud, all materials were melted into aluminosilicate glasses. On the basis of 17.2Fe_2O_3-5.7CaO-18.2Al_2O_3-50SiO_2-5.9Na_2O-3TiO_2 system glasses, [Al_2O_3]/[CaO] mass ratio changed further. For each sample, the assignment of IR absorption bands for aluminosilicate glasses was investigated by Fourier transform infrared spectroscopy and the glasstransition temperature and high temperature molten state were studied by differential scanning calorimetry. According to X-Ray diffraction and differential scanning calorimetry, the behavior of crystallization was analyzed. The results show that the glass structures of three-dimensional network are depolymerized and the amount of non-bridging oxygens increases gradually with network modifier CaO replacing network intermediate Al_2O_3 when [Al_2O_3]/[CaO] ratio of aluminosilicate glass decreases from 4.05 to 0.66, resulting in decreasing density, melting temperature, crystallization peak temperature and glass-transition temperature. As [Al_2O_3]/[CaO] mass ratio decreases, the concentration of crystallized phase maghemite（γ-Fe_2O_3） will increase which provides the possibility for production of black glass-ceramic further.

The Effect of ZnO on the Physicochemical and Mechanical Properties of Aluminosilicate Dental Cements

In this study,the effect of the addition of various amounts of ZnO(0,1,2,and 3 wt.%)to aluminosilicate bioactive glass(BGs)network(SiO_(2)-Al_(2)O_(3)-P_(2)O_(5)-CaF_(2)-CaO-K_(2)O-Na_(2)O)on the mechanical properties of the fabricated glass ionomer cement(GIC)samples was studied.The GIC samples were fabricated by mixing the synthesized aluminosilicate BGs with Riva-self cure liquid.The synthesized aluminosilicate glass was characterized using differential thermal analysis(DTA),X-Ray diffraction(XRD),Fourier-transform infrared spectroscopy(FTIR),and scanning electron microscopy(SEM).Besides,the mechanical properties of GICs were evaluated using Vickers microhardness and Diametral tensile strength(DTS)test.According to DTA analysis,the glass transition temperature(Tg)of aluminosilicate BGs was decreased from 575 to 525°C.According to the results,the aluminosilicate BGs with an amorphous state(~90%)and the grain size of 36μm were synthesized.Doping of the ZnO to glass network up to 3 wt.%could increase the amorphous phase up to 95%and decrease the grain size of the particles up to 28μm.The microhardness and DTS of the GIC samples containing the aluminosilicate BGs were about 677 Hv and 8.5 MPa,respectively.Doping of ZnO to the glass network increased the mentioned values up to 816 Hv and 12.1 MPa,respectively.

Effect of ZnO,La_(2)O_(3),and YF_(3)on Crystallization and Rehological Behavior of Y_(2)O_(3)-Al_(2)O_(3)-SiO_(2)Glass

The effect of substitution La_(2)O_(3)and YF_(3)as network modifiers respectively for Y_(2)O_(3),and ZnO as intermediate oxide for Al_(2)O_(3)on crystallization and viscous behavior of Y_(2)O_(3)-Al_(2)O_(3)-SiO_(2)glass was studied.La_(2)O_(3)and YF_(3)substitution for Y_(2)O_(3)decreases the melting temperature of studied glass from 1402 to 1346 and 1379℃,and the activation energy of viscous flow decreases from 340 to 250 and 265 kJ/mol.Meanwhile,ZnO substitution for Al_(2)O_(3)decreases the melting temperature to 1379℃while increases the activation energy of viscous flow to 542 kJ/mol,due to their different role in glass structure.Substitution ZnO for Al_(2)O_(3)refines and homogenizes the crystals size and lowers crystallinity because the nucleation and crystal growth are depressed by higher activation energy of crystallization and change of crystallization mechanism from bulk crystallization to surface crystallization.Replacement of Y_(2)O_(3)by La_(2)O_(3)and YF_(3)respectively also decreases the crystallinity of Y_(2)O_(3)-Al_(2)O_(3)-SiO_(2)glass ceramic due to competitive and hindering effect on the rearranged atoms,structural units and groups required by precipitated two crystals.Besides,y-Y2Si2O7,precipitation of Y4.67(SiO4)3O,ZnAl_(2)O_(4),and Y3Si3O10F were observed respectively due to incorporation of La_(2)O_(3),ZnO,and YF_(3).

基于团簇加连接原子模型的一种工业微晶玻璃成分优化初探

本团队提出的团簇加连接原子模型从结构根源上揭示了硅酸盐玻璃的成分载体,即硅酸盐玻璃的成分式由总数为16个的三价单元{M_(2)O_(3)}和四价单元{Si_(2)O_(4)}构成。本工作引入该模型,对一种工业微晶玻璃MT3A进行了成分优化,并进行玻璃制备和晶化,最后对样品进行结构和性能表征。在获得的新的透明微晶玻璃中,MT3C的透过率为89%,抗弯强度和硬度分别为155 MPa和652 HV;MT3D的透过率为92%,抗弯强度和硬度分别为134 MPa和655 HV。

白光LED用Phosphor-on-Glass(PoG)材料的制备与表征

采用商业Ce^3+∶YAG荧光粉包埋钇铝硅酸盐玻璃并在该体系玻璃转变温度附近进行烧结的方法,成功制备了荧光粉粘附在玻璃表面上的复合材料(Phosphor-on-Glass,PoG)。利用XRD、SEM和荧光光谱仪等研究了PoG材料的物相、显微结构和变温发光性能。研究结果表明:PoG材料结构为荧光粉/玻璃/荧光粉复合体,Ce^3+∶YAG荧光粉粘附在玻璃上下表面且均匀分布,其形貌与颗粒大小未发生明显变化。固定烧结时间为10h,PoG材料的荧光强度随着烧结温度的增加先增强后减弱;PoG材料的发光抗热淬灭性能较好(热激活能为0.22eV),这说明Ce^3+∶YAG荧光粉的优良发光性能在PoG材料中得到了很好地保存。以PoG材料封装的白光LED样品在100mA电流驱动下,获得白光输出,其中最接近纯白光(0.33,0.33)的LED光效为69.8lm/W,相关色温为5873K,显色指数72.3。由于Ce^3+∶YAG荧光粉缺乏红色发光,尝试在钇铝硅酸盐玻璃基质中掺杂Eu3+以增加红色发光部分,获得光效为52.1lm/W,相关色温为3910K,显色指数75.8的暖白光输出。

Effect of Y_2O_3 on the crystallization kinetics of TiO_2 nucleated LAS glass for the production of nanocrystalline transparent glass ceramics

Crystallization kinetics of metastable B-quartz solid solution as a desirable phase for the production of trans- parent lithium aluminosilicate （LAS） glass ceramics was investigated in the presence of Y203. Accordingly, differential thermal analysis scans were performed thoroughly to study the mechanism of crystallization kinetics. The aim of this investigation is to discover the complicated mechanism of crystallization process in the presence of co-additives and ac- cordingly find a way for increasing the transparency of glass ceramics. It is shown that the bulk （3D） growth is intensively increased by the enhancement of Y203. Then again, reducing nucleation and increasing growth mechanisms were recog- nized for the LAS system in the presence of Y2O3. Results of the investigation illustrate that when co-additives are added to glasses, it is necessary to nucleate the optical component separately before the growth process.

Study on Glass Fiber Dispersion Technology in SiO_2 Aerogel-glass Fiber Composite Insulation Materials

In order to improve the mechanical properties of SiO_2 aerogel-glass fiber composites, effects of different solvents(cyclohexane, n-hexane, ethanol, acetone) and different dispersing modes(planetary ball milling, ultrasonic dispersion and mechanical stirring) and dispersing duration(10-40 min) on the dispersion of chopped alkali-free glass fiber bundles were studied to determine the best dispersion process. On this basis, the materials were batched according to the mass fraction of SiO_2 aerogel powder to chopped alkali free glass fiber bundles of 90:10, and a certain amount of zinc oxide light-screening agent and phenolic resin binder were added. SiO_2 aerogel glass fiber composite specimens were prepared by direct adding chopped alkali free glass fiber bundles and pre-dispersed chopped alkali free glass fiber bundles, respectively. The cold crushing strength and the thermal conductivity at different surface temperatures(300, 400, 500 and 600 ℃, respectively)of the specimens were measured. The results show that:(1) the optimum dispersion process of chopped alkali-free glass fiber bundles is using ethanol as solvent and mechanical stirring for 30 min;(2) pre-dispersion of chopped alkali-free glass fiber bundles has little effect on the thermal conductivity of SiO_2 aerogel-glass fiber composites but can improve the cold crushing strength.

Compatibility between glass sealants and electrode materials of solid oxide fuel cells

BaO-CaO-Al2O3-SiO2-La2O3-B2O3 system glass materials were investigated as sealants for a solid oxide fuel cell （SOFC）. The transition temperature （Tg and the crystal temperature （Td） values decrease greatly with the increase of BaCO3 content when the other components do not change. For the thermal expansion coefficient （TEC） values, the trend is inverse. The sealant has superior thermal expansion coefficient matching properties with La（Sr）MnO3 （LSM） cathode, La（Sr）FeO3 （LSF） cathode, Ni-LDC （La doped CeO2） anode, and Ni-YSZ （yttria stabilized zirconia） cermet anode. The sealant also has superior stability, compatibility, and good bonding characteristic with these electrode materials at 800-900℃. The results indicate that the aluminosilicate system glass sealant possesses superior compatibility with electrode materials of the solid oxide fuel cell

Mineral-phase evolution and sintering behavior of MO–SiO_2–Al_2O_3–B_2O_3 (M = Ca,Ba) glass-ceramics by low-temperature liquid-phase sintering

In this work, network former SiO_2 and network intermediate Al_2O_3 were introduced into typical low-melting binary compositions CaO·B_2O_3, CaO·2B_2O_3, and BaO·B_2O_3 via an aqueous solid-state suspension milling route. Accordingly, multiple-phase aluminosilicate glass-ceramics were directly obtained via liquid-phase sintering at temperatures below 950°C. On the basis of liquid-phase sintering theory, mineral-phase evolutions and glass-phase formations were systematically investigated in a wide MO–SiO_2–Al_2O_3–B_2O_3(M = Ca, Ba) composition range. The results indicate that major mineral phases of the aluminosilicate glass-ceramics are Al_(20)B_4O_(36), CaAl_2Si_2O_8, and BaAl_2Si_2O_8 and that the glass-ceramic materials are characterized by dense microstructures and excellent dielectric properties.

Fe_(2)O_(3)含量及晶化工艺对无碱铝硅玻璃弹性模量的影响

选用CaO-MgO-Al_(2)O_(3)-SiO_(2)(CMAS)体系无碱铝硅玻璃为研究对象,设计8组Fe_(2)O_(3)组分变量,利用高温熔融法制备试验样品。利用XRD、SEM、TG-DSC等测试方法,先后对无碱玻璃样品的物相、析晶动力学、析晶行为和弹性模量等物化性能进行测试分析,进而探讨Fe_(2)O_(3)含量及晶化处理对无碱玻璃弹性模量的影响。结果表明:适量添加Fe_(2)O_(3)可以提升CMAS体系无碱玻璃的弹性模量,Fe_(2)O_(3)的质量分数为1.50%(F-6#)时,F-6#无碱玻璃弹性模量最大值为97.87 GPa,析晶活化能为347.1 kJ/mol,析晶指数n为1.383 4,为表面析晶。经整体析晶法晶化处理后,F-6#微晶玻璃析出的主晶相为钙长石相(CaAl_(2)Si_(2)O_(8)),晶体尺寸为200~400 nm;经烧结法晶化处理后,F-6#微晶玻璃析出的主晶相为钙长石相(CaAl_(2)Si_(2)O_(8)),晶体尺寸为300~500 nm。随着热处理温度的升高,析出主晶相数量变多,尺寸变大,但主晶相种类并未改变。由于钙长石的弹性模量小于基础玻璃,F-6#无碱玻璃析晶后所得微晶玻璃样品的弹性模量有所降低。

锂钠比对碱铝硅酸盐玻璃的化学强化性能影响

采用熔融淬冷法制备了不同锂钠比的锂铝硅酸盐玻璃,用两步化学强化法对样品进行了化学强化处理,研究了Li_(2)O取代Na_(2)O对铝硅酸盐玻璃机械性能和化学强化特征参数的影响。结果表明:随着Li_(2)O逐渐取代Na_(2)O,玻璃化转变温度从537.3℃减小至514.8℃。随着Li_(2)O含量增加,有利于化学强化中的第一步交换———Li^(+)-Na^(+)交换,提高交换层深度,但会对第二步Na^(+)-K^(+)交换产生抑制作用,导致K^(+)的交换深度减小。维氏压痕测试表明化学强化可以明显地提高Na-Li-x玻璃的硬度和抗裂性。随着Li_(2)O取代Na_(2)O,化学强化后玻璃的抗裂性先增后减,在Li_(2)O摩尔分数为10%时达到极值,为72.3 N,相比Li_(2)O摩尔分数为5%时的值提升了69.3%,引入适量的Li_(2)O会提高玻璃的耐径向开裂能力。

超薄铝硅酸盐玻璃离子交换工艺与性能研究

选择纯KNO_(3)为熔盐,采用一步法和二步法对可用于手机显示屏的超薄玻璃进行离子交换强化。利用EDS对离子交换玻璃的离子浓度分布进行测试表征,研究了离子交换温度(380℃~440℃)、时间(1 h~12 h)对玻璃的离子交换深度、表面应力、显微硬度、透过率及化学稳定性的影响。结果表明:温度的升高和时间的延长有利于玻璃表面应力和显微硬度的提高,但当温度超过400℃,且时间超过2h后,玻璃出现应力松弛效应;二步法增大了离子浓度梯度,进一步提高了玻璃的表面应力和显微硬度;离子交换过程在不降低透过率的同时提高了玻璃致密度及化学稳定性。相关结论对手机显示屏领域超薄玻璃的强化具有指导意义。

含钇锆酸盐纳米晶的钠铝硅透明微晶玻璃制备及性能研究

在钠铝硅玻璃体系引入氧化钇和氧化锆实现玻璃中钇锆酸盐纳米晶的可控生长,研究纳米晶对玻璃力学性能及化学强化性能的影响。研究结果表明,钇锆酸盐纳米晶析出能够一定程度上提高玻璃的力学性能,其中m(Al_(2)O_(3))/m(Na_(2)O)=1时的样品在经过800℃/2 h的热处理后,维氏硬度相比于原始样品提高了4.76%。此外,钇锆酸盐纳米晶析出后能够有效促进化学强化过程中K^(+)与Na^(+)交换,增加离子交换层深度,进一步提高微晶玻璃的力学性能,化学强化处理可使微晶玻璃的显微硬度相比原始样品提高20%。

Dependence of spectroscopic properties on doping content and temperature of bismuth-doped lanthanum aluminosilicate glass

The effects of bismuth doping content and temperature on the absorption property and near-infrared （NIR） luminescence of Bi-doped La2O3-Al2O3-SiO2 （LAS） glasses are presented. The emission intensity reaches the maximum when the Bi2O3 content in 3.0Bi-LAS is 1.83%. The emission spectra reach their peaks at 1 190 and 1 117 nm, with full-width at half-maximum （FWHM） values of 330 and 228 nm under 500 and 700-nm excitations, respectively. As the Bi203 content increases, the peak wavelengths and FWHMs of emission bands increase, but their lifetimes decrease. The lifetime of 2.0Bi-LAS is 460 μs at 9 K, and is almost temperature independent until 350 K. The NIR emission of Bi in the system has strong resistance to thermal quenching from 9 to 350 K.

锂铝硅玻璃对锆英石溢流砖的侵蚀性研究

玻璃溢流下拉法成型工艺中玻璃组分与溢流砖的匹配性至关重要。通过静态侵蚀实验和界面分析,研究不同组分锂铝硅玻璃对锆英石溢流砖的侵蚀性。实验结果表明:锂铝硅玻璃组成中氧化钠含量对锆英石溢流砖的侵蚀影响显著,氧化钠含量越高,锆英石分解温度越低;相同的玻璃组成,实验温度越高,玻璃对溢流砖的侵蚀越严重。

La_(2)O_(3)和Y_(2)O_(3)对高铝盖板玻璃结构及性能的影响

研究了不同添加量的La_(2)O_(3)和Y_(2)O_(3)对盖板用化学强化高铝玻璃性能的影响,发现适当加入La_(2)O_(3)和Y_(2)O_(3)可提高玻璃生产的适应性、机械性质和化学强化性能。加入La_(2)O_(3)和Y_(2)O_(3)可显著降低高铝玻璃的高温黏度,La^(3+)和Y^(3+)总物质的量分数每增加0.5%,玻璃澄清温度降低6~20℃。加入La_(2)O_(3)和Y_(2)O_(3)提高了玻璃的杨氏模量、剪切模量和显微维氏硬度;当La^(3+)和Y^(3+)总物质的量分数为1.5%时,玻璃杨氏模量、剪切模量和显微维氏硬度达到最大,分别为84.33、33.90和6.48 GPa。随La_(2)O_(3)和Y_(2)O_(3)含量的增加,化学强化后玻璃表面压应力(CS)有先增大后减小的趋势,应力层深度(DOL)有先基本不变后增大的趋势,且CS比对照组最多提升28%。拉曼光谱分析发现在La^(3+)和Y^(3+)总物质的量分数为0~1.5%时,随着玻璃中La^(3+)和Y^(3+)含量的增加,非桥氧含量基本不变,而受碱金属影响的桥氧含量显著增加;当La^(3+)和Y^(3+)总物质的量分数为1.5%~2.5%时,增加La^(3+)和Y^(3+)含量可显著提高玻璃中非桥氧含量。

添加CeO_2的Li_2O-Al_2O_3-SiO_2系微晶玻璃的晶化和性能研究

采用差热分析,X射线衍射分析和扫描电镜等分析手段研究了添加质量分数为5%CeO2对Li2OAl2O3SiO2系微晶玻璃形核和晶化的影响。结果表明:添加5%CeO2使该体系玻璃转变温度降低,晶化峰值温度降低,最佳成核温度从760℃降低到730℃。晶化过程中,β石英固溶体首先从玻璃中析出,在较高温度,β石英固溶体转变为β锂辉石固溶体。通过计算发现,添加CeO2后,样品的晶化活化能E和晶化指数n从添加前(323±7)kJ/mol,2.8±0.2变为(282±7)kJ/mol,3.2±0.2,说明了添加CeO2在降低玻璃的粘度的同时促进了玻璃晶化,而对材料的透明性与热膨胀系数等影响很小。