Metastable Immiscibility Surface in the System Na2O-B2O3-SiO2*

Opalescence and clearing techniques were used to determine the metastable immiscibility surface for sodium borosilicate solutions. These results indicate that a three-liquid region, which may or may not be metastable to two-liquid regions, underlies the immiscibility surface.     

Na2O-B2O3-SiO2玻璃结构中硼配位状态的研究

本文主要探讨玻璃熔体在不同的温度处理情况下对硼硅酸盐玻璃结构的影响.通过红外光谱和核磁共振谱分析了硼硅酸盐玻璃在不同温度处理情况下的结构变化.研究结果表明:硼硅酸盐熔体从高温冷却下来,硼配位发生由三角体到四面体的转变,并且硅氧网络聚集导致Q3的含量降低.运用NMR研究温度与硼硅酸盐熔体结构关系发现,高温有利于[BO3]及Q3的存在,反之,低温状态下[BO4]以及Q4的比例更高.     

含PbS微晶掺杂Na2O-B2O3-SiO2玻璃的制备及其光学性质

采用溶胶－凝胶方法合成了含有硫化铅的钠硼硅干胶,通过与硫化氮气体反再进行密实化处理,成功地制备了含有硫化铅微晶的钠硼硅系统玻璃。     

Na2O-B2O3-SiO2-TiO2玻璃分相与析晶的研究

熔融分相法是制备负载型纳米TiO2光催化材料的新方法。该方法是以Na2O-B2O3-SiO2-TiO2系为研究对象,通过制备不同组成的样品,并进行X射线分析及显微分析,进一步研究了熔融分相法中玻璃分相与TiO2析晶的关系。结果表明:组成在玻璃分相区域的样品,有玻璃分相现象产生,TiO2晶体能够析出,而在未分相区域的组成,样品中没有产生玻璃分相,TiO2晶体不能析出;玻璃分相的结构影响了TiO2晶体的生长,相同热处理条件下,组成中硅含量越少,其玻璃分相程度越大,TiO2析晶越容易,TiO2的析晶尺寸越大。     

金刚石增强Na2O-B2O3-Al2O3-SiO2系陶瓷基复合材料的界面研究

以Na2 O-B2 O3-Al2 O3-SiO2系低温玻璃为基础结合剂烧制金刚石增强陶瓷基复合材料,利用扫描电子显微镜、X射线能谱、X射线光电子能谱、拉曼光谱及力学性能测试仪等对其界面结合强度、界面处元素分布及界面化学键进行了表征.结果表明,Na2 O-B2 O3-Al2 O3-SiO2系陶瓷结合剂与金刚石颗粒界面结合...     

Tm3+-Yb3+双掺Li2O-B2O3-SiO2系透明玻璃陶瓷的制备及表征

本文制备了以Li2SiO3为主晶相Li2O-B2O3-SiO2系透明玻璃陶瓷,并研究了B2O3的含量对于玻璃陶瓷结构的影响.利用DSC、XRD和SEM等测试手段进行了表征.以Tm3+/Yb3+共掺作为上转换研究对象,研究了该系玻璃陶瓷的光谱性质.在980 nm激光激发下,Tm3+/Yb3共掺的LBS系玻璃陶瓷中观察到强的474 nm的蓝色、650nm的红色上转换发光,并确定蓝红光均为三光子过程.研究了上转换发光与Tm3+/Yb3+质量比的关系.     

Criterion for estimating the number of phases in phase-separated glass of the Na2O-K2O-B2O3-SiO2 system by dilatometric analysis

The data of dilatometry and electron microscopy of four series of xNa₂O-(8 ? x)K₂O-32B₂O₃-60SiO₂, xNa₂O-(8 ? x)K₂O-22B₂O₃-70SiO₂, xNa₂O-(6 ? x)K₂O-34B₂O₃-60SiO₂, and xNa₂O-xK₂O-(40 ? 2x)B₂O₃-60SiO₂ phase-separated glass heat-treated at 550°C for 144 h (for glass containing 70 mol % SiO₂) and 24 h (for glass containing 60 mol % SiO₂) for separation on phases are summarized. The comparison of dilatometric data and electron microscopy allow one to conclude that glass with a difference between the onset deformation temperature and a glass transition temperature of more than 100°C is phase-separated; and glass with a difference of less than 65°C is single-phase. Curves for the glass transition temperature as a function of the K₂O content reveal a mixed alkali effect, namely, minimums for glass containing 60% SiO₂, and maximums for glass containing 70% SiO₂.     

PRELIMINARY STUDY ON PORTIONS OF SYSTEMS Na2O-CaO-AI2O3-Fe2O3 AND Na2O-CaO-Fe2O3-SiO2*

Portions of the quaternary system Na₂O-CaO-Al₂O₃-Fe₂O₃ have been studied by the exploration of (1) the plane CaO-4CaO.Al₂O₃°Fe₂O₃-(Na₂O + 3Al₂O₃) and (2) planes above the base system CaO.5CaO.3Al₂O3–2CaO.Fe₂O₃ which contain successively increasing amounts of Na₂O up to 6%. A portion of the quaternary system Na₂O-CaO-Fe₂O₃-SiO₂ has been studied by the exploration of a plane containing 5% of Na₂O above the base system CaO-2CaO.SiO₂-CaO.Fe₂O₃. In the pseudosystem CaO-4CaO.Al₂O₃.Fe₂O₃-(Na₂O + 3A1₂O₃) the compound Na₂O.-8CaO.3A1₂O₈ was found to exist as a primary phase, and the area in which the plane cuts the Na₂O.8CaO.3A1₂O₃ primary-phase volume was established. Three points on uni-variant curves were located. The iron phase (4CaO.A1₂O₃.Fe₂O₃ solid solution) was observed to exist in a solid-solution series. In the system Na₂O-CaO-5CaO.3Al₂O_3--2CaO.Fe₂O₃ it was found that the compound Na₂O.8CaO.3Al₂O3 appears at an Na₂O concentration of 4.2%. As soda, however, is taken into solid solution by other phases, it was not feasible at this time to determine the invariant point for Na₂O.8CaO.3A1₂O₃, 3CaO.Al₂O₃, 5CaO.3A1₂O₃, and 4CaO.Al₂O₃.-Fe₂O_a solid solution. In the system Na₂O-CaO-2CaO.SiO₂-CaO.Fe₂O₃ no ternary compounds were observed up to the 5% limit of Na₂O employed. A soda-containing phase occurred in solid solution with α-2CaO.SiO₂, which may precipitate on cooling, forming inclusions in the ß-2CaO.SiO₂, or enter into reaction with the glassy phase.     

Temperature dependence of the viscosity for some glasses in the Rb2O-B2O3-SiO2 system

The temperature dependences of the shear viscosity of glasses in the Rb₂O-B₂O₃-SiO₂ system are investigated using the bending method on a quartz viscosimeter in the viscosity range 10¹¹-10¹³ P.     

Temperature dependences of the viscosity for some glasses in the Cs2O-B2O3-SiO2 system

The viscosities of glasses in the Cs₂O-B₂O₃-SiO₂ system are measured by the bending method on a quartz viscosimeter in the temperature range 300–670°C. The temperature dependences of the viscosity of the glasses under investigation are determined, and the temperatures corresponding to the viscosities equal to 10¹¹, 10¹², and 10¹³ P are calculated.     

Li_2O-Na_2O-B_2O_3-SiO_2系无铅低温透明熔块的研制

探索用Li2O-Na2O-B2O3-SiO2新的配方系统配制无铅低温透明熔块的方法。制得使用温度为740~780℃的低温无铅透明熔块,以熔块配制成的低温透明熔块釉可作为生产陶瓷装饰色料中的低温熔剂。     

掺Li2O-B2O3-SiO2玻璃低温烧结MgTiO3-CaTiO3陶瓷及其微波介电性能

研究了Li2O-B2O3-SiO2玻璃(LBS)对MgTiO3-CaTiO3(MCT)介质陶瓷烧结特性、相组成和介电性能的影响,分析了MCT陶瓷与银电极的共烧行为.结果表明:通过液相烧结,LBS能有效降低MCT烧结温度至890℃.X射线衍射结果显示有Li2MgTi3O8、硼钛镁石以及Li2TiSiO5等新相生成.随着LBS添加量的增大,陶瓷致密化温度和饱和体积密度降低,介电常数εr品质因数与谐振频率乘积Q×f也呈现下降趋势,频率温度系数δf向负值方向移动.添加质量分数为20%的LBS的0.97MgTiO3-0.03CaTiO3陶瓷在890℃烧结4h,获得最佳性能:εr=16.4,Q×f=11 640GHz,τf=-1.5×10-6/℃.陶瓷与银电极共烧界面结合状况良好,无明显扩散.该材料可用于制造片式多层微波器件.     

Studies in Lithium Oxide Systems: III,Liquid Immiscibility in the System Li2O-B2O3-SiO2

Glasses within the ternary system Li₂O-B₂O₂SiO₂ containing less than 25.6% Li₂Ocan be broadly classified into three groups according to their behavior during cooling or heating. One group, containing either more than 18% Li₂Oor less than 20% SiO₂, yields clear glasses during slow or rapid cooling. The second group, containing approximately 5 to 15% Li₂O and 26 to 90% SiO₂, yields dense white opal glass during slow or rapid cooling. The third group, located at the outer edge of the second group, cools to room temperature as clear glasses but develops opacity when reheated to temperatures between 550° and 8800°C. It has been shown by electron microscopy that the opacity is due to liquid immiscibility, the matrix glass containing well-formed spheres of the dispersed phase. Some of the clear glasses of both groups have been shown to consist of two immiscible phases. The size of the dispersed units in the spontaneous opal glasses and also the reheat opal glasses can be controlled by the variation of the reheat treatments. The phase separation reported here is beyond the resolution of the petrographic microscope and can be detected only with the high resolution of the electron microscope. Accessory evidence is given to show that the phases are non-crystalline.     

Na2O-Al2O3-SiO2-P2O5玻璃的结构和析晶性能研究

采用熔融-淬冷法制备了不同(Al₂O₃+P₂O₅)含量的碱铝硅酸盐玻璃,通过拉曼光谱、X射线衍射光谱、扫描电镜研究了其结构特征和析晶性能。发现随着(Al₂O₃+P₂O₅)含量减少,玻璃中Na₂O含量增加,玻璃化转变温度从685 ℃降低到622 ℃,当减少至摩尔分数为22%时,出现析晶峰且起始析晶温度降低。拉曼光谱表明Q⁴_P对应的拉曼峰强度变低且逐渐向低波数方向移动,说明Na₂O作为网络修饰体使硅酸盐玻璃结构逐步解聚,玻璃的析晶能力逐渐增强。结果表明:当(Al₂O₃+P₂O₅)摩尔分数为22%时热处理后的样品存在晶型转变,700 ℃热处理时以NaAlSiO₄霞石晶体为主,900 ℃时转变为以Na_6.8Al_6.3Si_9.7O₃₂霞石晶体为主。当(Al₂O₃+P₂O₅)的摩尔分数为21%和20%时,热处理后的样品能稳定析出Na₃PO₄和Na_6.8Al_6.3Si_9.7O₃₂晶体。热处理后的样品析出了耐酸侵蚀性较差的富磷相和Na₃PO₄晶体,导致化学稳定性变差。     

Na2O-CaO-Al2O3-SiO2系统微晶玻璃的析晶动力学研究

Na2O-CaO-Al2O3-SiO2系统微晶玻璃是一种新型建筑材料,该材料不仅具有一定的力学性能,还具有良好的装饰效果.本文采用差热分析 (DTA)方法对 Na2O-CaO-Al2O3-SiO2系统微晶玻璃的析晶动力学参数进行了测定,研究了该系统微晶玻璃析晶动力学.其结果表明:随着CaO含量的增加,该系统微晶玻璃的析晶活化能E和动力学析晶参数k(Tp)总体上是上升的.晶化指数n均小于3,表明该系统微晶玻璃以表面析晶的方式析晶.     

Phase equilibria and thermodynamic properties of components in the Cs2O-B2O3-SiO2 system at high temperatures

The phase equilibria in the Cs₂O-B₂O₃-SiO₂ system are investigated in the temperature range 873–1073 K by the annealing-quenching technique, high-temperature microscopy, and X-ray powder diffraction analysis. The vapor composition, the activities of the components, and the Gibbs energies of glasses and melts in the Cs₂O-B₂O₃-SiO₂ system are determined at a temperature of 1020 K. It is demonstrated that glasses and melts in the Cs₂O · B₂O₃-Cs₂O · SiO₂ system are characterized by positive deviations of the CsBO₂ activities and negative deviations of the Cs₂O · SiO₂ activities from ideal behavior. As a consequence, the deviations of the Gibbs energies from ideal behavior change their sign.     

Corrosion resistance of nonstoichiometric gadolinium zirconate coatings against CaO-MgO-Al2O3-SiO2 silicate

Gadolinium zirconate is a promising next-generation thermal barrier coating material and its CaO-MgO-Al₂O₃-SiO₂ (CMAS) resistance needs to be further increased. In this study, three gadolinium zirconate coatings with different Gd/Zr ratios are successfully prepared via atmospheric plasma spray using amorphous feedstock. Their mechanical properties and corrosion resistance are investigated. The Young’s moduli and hardness of as-sprayed coatings are comparable with the gadolinium zirconate coatings reported in previous literature. Furthermore, the higher Gd content promotes the formation of the Gd-apatite and the depletion rate of CMAS corrosion. As a result, the infiltration depth of Gd_2.3Zr_1.7O_6.85 coating after 24 h annealing decreases up to 35 % compared with those of Gd_2.0Zr_2.0O_7.0 and Gd_1.8Zr_2.2O_7.1, exhibiting an enhanced long-term corrosion resistance. This work develops a viable fabrication method to produce non-stoichiometric gadolinium zirconate coatings with tailorable CMAS corrosion resistance and is expected to promote the future design of thermal barrier coatings with long service life.     

Simulation of the thermodynamic properties of glass-forming melts in the Na2O-B2O3-SiO2 system in the framework of the generalized lattice theory of associated solutions

The possibility of calculating the thermodynamic properties of melts in the Na₂O-B₂O₃-SiO₂ system (as in the previously studied Cs₂O-B₂O₃-SiO₂ system) formed by two glass-former oxides (B₂O₃, SiO₂) and one modifier oxide (Na₂O) with the use of the vacancy variant of the generalized lattice theory of associated solutions is demonstrated. A comparison with the experimental thermodynamic functions previously determined by the electromotive force method and high-temperature mass spectrometry at temperatures of 1200, 1273, and 1350 K shows that the calculations performed within this approach lead to reliable thermodynamic functions. It is noted that the proposed model ignores the change in the coordination number of boron atoms to four and the possibility of forming associates in melts of compositions lying in the metastable phase separation region at temperatures higher than the phase separation temperature.     

Na2O-MgO-Al2O3-SiO2建筑装饰微晶玻璃的研究

利用浇铸法制备了MgO-Al2O3-SiO2微晶玻璃。采用示差扫描量热法(DSC)、X射线衍射(XRD)、扫描电子显微镜(SEM)等分析方法,研究NMAS微晶玻璃玻璃组成中Al2O3/SiO2对微晶玻璃的析晶和性能的影响。结果表明:玻璃中析出的主晶相为镁橄榄石。随Al2O3/SiO2的减小,镁橄榄石的衍射峰强度逐渐减弱,次晶相为a-堇青石。C3、C4中还有很少量-6-1的顽辉石相。微晶玻璃热膨胀系数逐渐升高,抗折强度和硬度逐渐减小。C1在600℃时的热膨胀系数为7.01×10K,抗折强度为115MPa,硬度达为8.0GPa。     

Sintering of sodium conducting glass ceramics in the Na2O-Y2O3-SiO2-system

A solid electrolyte is a core component for the development of low temperature sodium batteries with metallic Na-anode. The Na₅YSi₄O₁₂ (N5) composition in the Na₂O-Y₂O₃-SiO₂ system shows a high ionic conductivity comparable to NASICON or β-Al₂O₃. Up to date glass ceramic solid electrolytes of this type have been mainly prepared by crystallization of monolithic, molten glass components. We show that this material can be processed via the glass-ceramic powder route starting with a glass powder. A glass with a composition according to the stoichiometry of the Na₅YSi₄O₁₂-phase and tailored by addition of P₂O₅ allows the separation of sintering and crystallization of the glass powder resulting in dense microstructure. Thermophysical properties and phase content have been correlated with ionic conductivity. The densification and crystallization are completed at temperatures below 1100 °C. Grain conductivities up to 0,18 mS cm^?1 at room temperature in sintered glass ceramic microstructures are demonstrated.