Microstructure Characterization of Simulated Tri-Isotropic Particles Embedded in Alkaline Borosilicate Glass

A preliminary study of the encapsulation of tri-isotropic (TRISO) coated particles in alkaline borosilicate glass (ABG) using melting and casting methods is presented. ABG has been developed to encapsulate simulated TRISO fuel particles that are used as nuclear fuel elements in Very High Temperature Reactors. Encapsulation is an alternative to vitrification and it is a process in which radioactive waste is encapsulated within a composite as a first barrier and a glass matrix as a second barrier. This provides two barriers against leaching and diffusion of the radioactive waste once buried in the geological repository. The study investigates the possibility of achieving high densification of glass–graphite composite by sealing the pores of TRISO particles surrogate (28 wt% CeO₂, 70 wt% graphite, and 2 wt% poly-ethylene glycol) with molten ABG at 600°C. This article follows the carbon phases during the encapsulation and highlights the interaction area between the carbon and glass phases before and after melting, using a polarized laser source (Ar, 514 nm). The laser analysis revealed that the graphite no longer was retained in graphene hexagonal structure and that it was linked with the glass network as disordered carbon atoms.     

硫酸铅在硼硅酸盐玻璃熔体中的溶解特性

针对高硫、高钠的高放废液玻璃固化过程中Na₂SO₄极易分解和分相的问题,本文提出在模拟高放废液中加入适量Pb(NO₃)₂溶液将Na₂SO₄转变成PbSO₄,再利用熔融法制备硼硅酸盐玻璃固化体。首次采用在钢铁材料中广泛应用的高温激光共聚焦显微镜原位观察PbSO₄在玻璃熔体中的溶解特性,并探究不同温度(800～1 150 ℃)下PbSO₄与硼硅酸盐玻璃混合熔制后的热稳定性以及玻璃体中的硫含量。结果表明:在硼硅酸盐玻璃中掺入6%(质量分数,以SO₃计)PbSO₄的样品在800 ℃和900 ℃为均匀的玻璃陶瓷,其中800 ℃时主要含SiO₂及少量BaSO₄、PbSO₄晶体,900 ℃时SiO₂晶体减少,BaSO₄晶体增多,PbSO₄消失并出现CaMgSi₂O₆晶体;样品在1 000 ℃时玻璃表面开始出现由PbO、BaSO₄、LiNaSO₄晶体组成的白色分相,在1 000～1 100 ℃时圆形PbO晶体逐渐长大,BaSO₄晶体由块状变为条状;样品在800～1 000 ℃时玻璃体中的硫含量基本保持不变,随着温度进一步升高硫含量迅速下降。     

Redox-Controlled Solubility of Palladium in a Borosilicate Glass Melt

Palladium establishes the Pd²⁺–Pd⁰ redox equilibrium in a reference alkali borosilicate melt. Most of the palladium exists as the insoluble metal, with only a small fraction of the palladium present as the divalent palladium ion dissolved in the melt. The relative reduction potential of this Pd²⁺–Pd⁰ redox couple in the reference glass melt is greater than such easily reduced couples as Ni³⁺–Ni²⁺ and Mn³⁺–Mn²⁺. Palladium metal in glass melts containing appropriate amounts of nickel and sulfur readily partitions into an immiscible nickel sulfide phase; palladium also tends to associate with tellurium in insoluble particulates.     

Model for Sintering Devitrifying Glass Particles with Embedded Rigid Fibers

We extend the Clusters model to account for the presence of rigid inclusions and use it to analyze the experimental sintering kinetics of composites of 60SiO₂·24B₂O₃·16Na₂O glass particles and zirconia fibers. We followed the densification kinetics of such composites as a function of the particle size, volume fraction of fibers, fiber to pore size ratio, temperature, and time of thermal treatment. The parameters of the extended Clusters model are the glass particle size distribution and shape factor, the fiber volume fraction and radii, the glass viscosity and surface tension, the number of nucleating sites per unit surface, and the crystal growth rate in the parent glass. Hydrostatic tensions caused by the fibers were also included in the calculations. The modified Clusters model with only one adjustable parameter, which is largely dominated by viscosity but also includes particle shape, allowed us to account for the effect of surface crystallization and fiber content as inhibitors of densification and successfully describe the sintering kinetics of the studied composites.     

Effect of Thermal Treatment on Chemical Interaction Between Yttrium Borosilicate Glass Sealants and YSZ for Planar Solid Oxide Fuel Cells

This article is to address the bonding and sealing capability of two yttrium borosilicate glasses. These glass seals have been tested with AISI 441 steel and high-temperature solid electrolyte that is yttria-stabilized zirconia (YSZ), as a function of different heating durations for planar solid oxide fuel cell applications in air atmosphere. The diffusion couples were prepared by slurry coating and then subjected to heat-treatment for different time durations of 1, 100, and 500 h at 850°C. In addition to this, the diffusion couples with YSZ were also thermally cycled between room temperature and 850°C. These prepared diffusion couples have been characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive spectroscopy (EDS). XRD indicated surface crystallization of the coating glass/YSZ diffusion couple. MgY glass sample shows less devitrification than the CaY glass. The overall analysis of the resulting microstructure by SEM/EDS revealed improvement in adhesion with increase in time duration of heat treatment as well as thermally cycled sample without any detrimental phase formation. The diffusion couples with AISI 441 steel have shown good adhesion with crack-free interface.     

硼硅玻璃管道的应用

介绍硼硅玻璃管道的性能、特点和应用情况;阐述其安装方法及其注意事项。     

硼硅酸盐玻璃结构与其熔体性质研究

对硼硅酸盐玻璃结构及其熔体性质展开研究,通过红外光谱分析了Al2O3对硼硅酸盐玻璃结构的影响,测试了玻璃熔体的高温粘度和抗折强度.研究结果表明:当玻璃中Al2O3/SiO2物质的量比在1.2％～6.5％,(R2O-Al2O3)/B2O3的物质的量比在0.04 ～0.41范围内时,Al3+全部以[AlO4]形式存在,是玻璃网络形成体,B3+大部分以[BO3]的形式存在,是玻璃网络外体,少部分以[BO4]形式存在,是玻璃网络形成体.增加玻璃熔体中Al2O3的含量,玻璃中游离氧含量和[BO4]含量减少,[BO3]含量增加,玻璃的高温粘度增大,熔制温度升高,抗折强度降低.     

Chemical Durability of Lanthanum-Enriched Borosilicate Glass

The role of lanthanum in the alteration kinetics at different degrees of reaction progress was investigated at 90°C and pH 7 by complementary chemical (SIMS), morphological (SAXS), and structural (NMR, Raman, and EXAFS spectroscopy) approaches. In the first step of alteration, the forward dissolution rate diminishes with the addition of lanthanum, resembling to the behavior previously observed for zirconium. Over longer alteration time, the glasses with the highest lanthanum concentrations reach silicon saturation more slowly, but unlike zirconium, do not result in larger quantities of altered glass. Lanthanum is entirely retained in the alteration layer and is uniformly distributed; it undergoes hydrolysis and recondensation mechanisms, and its coordination number increases from 6 to 9 during leaching. Reconstruction of the alteration layer occurred more slowly at higher REE concentrations, with a slowdown in repolymerization of the silicate network and structuring of its porosity.     

Structure of Rhenium-Containing Sodium Borosilicate Glass

A series of sodium borosilicate glasses were synthesized with KReO₄ or Re₂O₇, to 10,000 ppm (1 mass%) target Re, to assess effects of large concentrations of rhenium on glass structure and fto estimate solubility of ⁹⁹Tc, a radioactive component in low active waste nuclear glasses. Rhenium was used as a surrogate for ⁹⁹Tc for laboratory testing, due to similarities in chemistry, ionic size, and redox. Magic angle spinning nuclear magnetic resonance, Fourier transform infrared spectroscopy, and Raman spectroscopy were performed to characterize the glasses. Si was coordinated in Q² and Q³ units, Al was four-coordinated, and B was mostly three-coordinated. The rhenium additions did not have significant effects on the glass structure up to approximately 3000 ppm Re by mass, the maximum concentration that remained dissolved in glass. Rhenium likely exists in isolated anions in the interstices of the glass network, as evidenced by polarized Raman spectrum of the Re glass in the absence of sulfate. Analogous to in similar glasses, is a network modifier and above solubility forms alkali salt phases on the surface and in the bulk. Comparisons of phase separation and crystallization in containing borosilicate glasses can also be made to containing glasses.     

硼硅酸盐玻璃与钠钙硅玻璃浮法成型的对比研究

总结了浮法成型工艺的特点,介绍了浮法工艺对普通钠钙硅玻璃的要求,在此基础上提出从玻璃的熔化和成型温度要求,粘度-温度曲线要求,析晶温度上限要求等几个方面探讨耐热高强硼硅酸盐平板玻璃浮法成型的要求.     

Dielectric Loss of Microstructurally Anisotropic Borosilicate Glass

Dhdelectric characteristics were determined for a microstructurally anisotropic borosilicate glass prepared by uniaxiallhd stretching phase-separated glass rods. The specimen showed a dielectric loss peak caused by the inhomogeneous microstructure; its magnitude varied with the orientation of the specimen with respect to the electric field direction. The results are in agreement with Sillars' theory.     

Oxidation Equilibrium of Iron in Borosilicate Glass

Ferrous/ferric equilibria were determined in alkali-alkaline-earth borosilicate glass as a function of temperature, oxygen partial pressure, and glass composition. Expected linear relations are found between log(Fe²⁺/Fe³⁺) and log( p O₂) or 1/ T . The slopes of the correlation with 10g( p O₂) are near the expected value of -0.25, but are found to decrease with increasing temperature. Reaction enthalpies determined from the correlation with 1/ T of –100 to –116 kJ/mol are similar to those reported for other silicate glasses. The ferroudferric equilibrium is not dependent on total iron content in the range 0.5 to 0.09% Fe₂O₃. More reducing conditions are required at lower temperatures to stabilize the amber chromophore. The ferroudferric equilibria are correlated to the number of bridging and nonbridging oxygen ions in the glass. The results suggest that the oxidation-reduction reaction can be written as: Fe²⁺+ (¹/₄)O₂+ (³/₂)O^2-= FeO₂⁻     

Specifics of Interaction Between Glass Batch Particles Through Two-Component Solution Interlayers

The capillary force and crystallization strength of glass batch components are studied moistening the batch with solvents of sodium carbonate, sodium sulfate, and other components. The obtained data can be used for solving problems related to moistening glass batches.__________Translated from Steklo i Keramika, No. 2, pp. 7 – 9, February, 2005.     

利用热膨胀仪研究硼硅酸盐玻璃的结构弛豫行为

针对目前差示扫描量热仪、红外光谱和Raman光谱等在分析不同玻璃性质弛豫行为上的局限性,提出了建立在玻璃热膨胀性能测试基础上的分析方法。在Rekhson提出的方案基础上,结合Moynihan法,采用Tool-Narayanaswamy-Moynihan唯象模型对玻璃容积在转变区内的弛豫行为进行了研究。测试了两种具有不同热历史的硼硅酸盐玻璃的热膨胀曲线,得到了相同结构弛豫参数,验证了这种方法的可靠性。结果表明:采用改进Rekhson法得到的硼硅酸盐玻璃弛豫函数在参考温度为830K时的比例系数x为0.89,活化能H为200kJ/mol,弛豫时间τr为200s,扩展指数β为0.55;对比Moynihan热容法,该方法虽在精确性上稍差,但在工业领域应用中具有非常大的潜力。     

硼硅酸盐玻璃对耐火材料的侵蚀研究

主要针对熔制硼硅酸盐玻璃时对锆刚玉砖、镁砖、硅砖的侵蚀情况进行实验分析.为合理选择熔窑耐火材料提供参考.     

Decomposition of Ruthenium Oxides in Lead Borosilicate Glass

Behaviors of apparent phase changes of Ru-containing oxides in lead borosilicate glass at high temperature have been investigated using X-ray diffraction and transmission electron microscopy in application to thick-film resistors. During firing of thick films containing Ru oxide powder and lead borosilicate glass frits, apparent phase changes of Ru oxides have been found to occur both ways between ruthenium dioxide and lead ruthenate pyrochlore via decomposition of one phase in glass and subsequent formation of the other. The formation of pyrochlore occurs in a lead-rich form, Pb₂(Ru_{2− x} Pb _x )O_6.5, whereas the formation of RuO₂ is characterized by a platelike morphology instead of initial globular morphology. A general tendency is observed that RuO₂ is stable in low-PbO glass compositions and at high temperatures, while Pb₂(Ru_{2− x} Pb _x )O_6.5 is stable in high-PbO glass compositions and at low temperatures, with the implication that the stability of these phases is dictated by the chemical activity of PbO in the glass melt.     

中国3.3高硼硅玻璃管发展历程(续)

正2.2硼硅玻璃3.3管发展历程2.2.1西方长期对我国禁运的高技术基础材料硼硅玻璃3.3是美国康宁公司20世纪初发明的优质玻璃,以商品名称Pyrex销售。其性能十分优越,在化学、生物学、微电子学等现代科学中广泛应用。由于生产难度大,仅有极少数企业能够生产。产品价格高,且高度垄断、技术严格保密。硼硅玻璃3.3是制造原子武器、生物武器、化学武器和科研、教学用高科技材料。自20世纪50年代以来西方国家将其列为禁运物资对我国封锁近半个世纪。     

Improvement of Protective Properties of Borosilicate Melt by Introducing Deoxidizers

The possibilities of improving the protective properties of borosilicate melts by adding deoxidizers are considered. The dependence of the rate of oxidation of steel 30KhGSA on Fe₂O₃ content in the melt is experimentally established. The rate of oxidation of steel 30KhGSA in a melt deoxidized by silicon carbide, silicon nitride, and by a boron-bearing product are determined.