Stress Development during Constrained Sintering of Alumina/Glass/Alumina Sandwich Structure

Stress development during the constrained sintering of a sandwich structure of alumina/glass/alumina has been studied. Stress distribution in the glass layer was calculated using a finite element method. The shear stress exhibited a maximum at the edge of the alumina/glass interface. The in-plane tensile stress, formed during constrained sintering, decreased from the interface of the alumina/glass to the middle of the glass in the z -direction, but increased from the edge to the center of glass in the x − y direction. This in-plane tensile stress reduces the driving force of densification, resulting in a larger x − y shrinkage and higher densification in the middle of the glass.     

硼硅酸盐泡沫玻璃研究

以C和Sb2O3组合作为发泡剂,通过粉末烧结发泡工艺制备了硼硅酸盐泡沫玻璃,采用SEM观察了试样的微观结构形貌,并研究了试样的耐酸腐蚀性能.结果表明:当发泡剂C的质量分数为0.9%、Sb2O3的质量分数为8.1%时,在1200 ℃、保温30 min条件下,可以制备出平均孔径为0.2～1.0 mm、气孔分布较均匀的硼硅酸盐泡沫玻璃.试样中气孔结构主要与气泡内的气体压力、玻璃的表面张力和粘度有关.将试样浸泡在0.1 mol/L的稀硫酸中做耐酸腐蚀性实验,60 d内试样的质量先有微量增加后保持不变,这主要是由于稀硫酸进入试样的气孔结构中后形成了一层保护膜,从而阻碍了进一步的侵蚀.     

Stress Required for Constrained Sintering of a Ceramic-Filled Glass Composite

The stress required for complete constrained sintering of a low-temperature cofirable ceramic-filled glass composite, i.e., borosilicate glass + alumina, has been investigated under uniaxial constant and cyclic loading. The required uniaxial stress to have complete constrained sintering, i.e., zero strain or strain rate in the perpendicular directions, is in the range of 20–250 kPa, which initially increases with temperature, reaches a maximum at 725°–800°C, and then decreases with increasing temperature. The above measured data exhibit a similar trend to those of required stress and sintering potential calculated using the viscous analogy for the constitutive relationship of a porous sintering compact.     

温度制度对硼硅酸盐泡沫玻璃结构的影响

实验以SiO2和H3BO3为主要原料制备了硼硅酸盐泡沫玻璃.通过改变烧成温度和保温时间,探讨了温度制度对泡沫玻璃的结构的影响.利用SEM分析了泡沫玻璃的气泡结构,并对试样进行了抗酸性测试.随着温度的提高和保温时间的延长,气泡的尺寸逐渐增大,直至连通、破裂.在1250 ℃保温60 min制得的泡沫玻璃的气泡结构最佳.在0.1 mol/L的稀硫酸中浸泡2个月,质量变化率为0.46%～2.28%.     

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。     

Faceting Behavior of Alumina in the Presence of a Glass

The faceting of alumina interfaces in the presence of a glass affects both grain growth and grain-boundary mobility during liquid-phase sintering. The geometry and movement of facets that form during this sintering process are expected to play an essential role in the development of the final microstructure, in particular, by their influence on the topology of the grain boundaries which ultimately control the properties of Al₂O₃ compacts. A new method for studying the interaction between Al₂O₃ and a glass has been developed. A thin sample of Al₂O₃ suitable for examination in a transmission electron microscope is prepared and examined and then reacted with SiO₂ and CaO via the vapor phase. This experimental approach allows the faceting behavior of glass/Al₂O₃ interfaces to be studied systematically without introducing unnecessary complications during subsequent sample preparation. Faceting occurs almost exclusively on the (0001) and {1 1 02} planes. The interaction between glass and certain structured grain boundaries in alumina has been studied using polycrystalline thin films.     

硼硅酸盐玻璃浸出前后结构变化的研究

硼硅酸盐玻璃作为最具工业化应用前景的高放射性废物的固化基材,其中的放射性核素主要以浸出方式进入生物圈.本工作采用了MCC-1静态浸泡法对在90℃去离子水中浸泡28 d后的硼硅酸盐玻璃的浸出行为进行了研究.借助电感耦合等离子体发射光谱(ICP-OES)、傅里叶红外光谱(FTIR)、拉曼光谱(Raman)以及掠入射X射线衍...     

全氧燃烧技术在高硼硅浮法玻璃窑炉上的应用探讨

介绍了全氧燃烧技术的特点和高硼硅玻璃的生产现状,探讨了全氧燃烧高硼硅浮法玻璃窑炉的结构特点,指出了全氧燃烧技术在高技术玻璃生产上的应用前景。     

钙钛锆石-钡硼硅酸盐玻璃陶瓷的制备及表征

采用熔融–热处理工艺制备了Si O2–B2O3–Ba O–Na2O–Ca O–Zr O2–Ti O2体系钙钛锆石基钡硼硅酸盐玻璃陶瓷,研究了Ca O、Ti O2、Zr O2(记为CTZ,摩尔比为2:2:1)含量对玻璃陶瓷相结构、显微结构的影响,采用产品一致性测试法(PCT)测试了玻璃陶瓷样品的抗浸出性能。结果表明:样品的玻璃转变温度为615~650℃且随着CTZ含量增加而升高。CTZ含量为35%的样品和CTZ含量为45%的样品分别在900和850℃附近出现了明显的放热峰。当CTZ含量≥30%时,钙钛锆石晶相开始析出;CTZ含量为45%时,样品中出现大量均匀分布的柱状钙钛锆石晶相;CTZ含量达55%时,样品致密性较差,除钙钛锆石晶相外还有榍石和二氧化硅晶相析出。PCT测试表明:CTZ含量为45%的样品具有较好的抗浸出性能,B和Na在42 d后的归一化质量损失约为0.1 g/m2,Si和Ca约为0.01 g/m2,与硼硅酸盐玻璃固化体处于同一数量级。     

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.     

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.     

无机抗菌硼酸盐玻璃材料的研究

采用高温熔融法，在硼酸盐玻璃的配合料中引入抗菌剂磷酸银，一次烧制而成制得抗菌玻璃材料，并对硼酸盐玻璃的抗菌性能和缓释性能进行了分析。结果表明：制备抗菌硼酸盐玻璃时，合适的银含量为1．5％-2．0％，处理温度在1100～1400℃即获得良好的抗菌效果和缓释性。     

Al2 O3对硼硅酸盐玻璃结构和性能的影响

硼硅酸盐玻璃具有优良的抗热冲击性能和优异的光学性能。主要探讨了Al2 O3对硼硅酸盐玻璃的结构和性能的影响。通过红外光谱测试分析了Al2 O3含量不同时玻璃的结构变化,测试了玻璃的热膨胀系数,转变温度、膨胀软化温度、粘度和化学稳定性。研究结果表明：Al2 O3的加入使得玻璃结构中[ BO4]减少,[ BO3]相应增加,从而使得玻璃结构疏松。玻璃的热膨胀系数增大,Tg 和膨胀软化点Td 降低,化学稳定性减弱;但玻璃的软化点Tf 在Al2 O3含量小于3%时,随Al2 O3含量增加有降低趋势,大于3%时随Al2 O3含量增加有增大的趋势。玻璃的高温粘度随Al2 O3的加入增大,但低温粘度减小。     

Sm3+掺杂碱锌硼硅酸盐玻璃析晶过程的微观结构研究

采用HTEM,NMR以及红外光谱技术,研究适宜半导体微晶掺杂的Sm3 掺杂碱硼硅酸盐基础玻璃在热处理过程中,玻璃结构的变化特点.研究结果表明,含Sm3 基础玻璃失透的主要原因在于在热作用下玻璃中[SiO4]4-以及[BO4]4-四面体结构首先分解形成了富硅相以及富硼相,稀土Sm3 则富集到富硼相中,并进一步析出了硼酸钐晶体;通过优化玻璃的组成能够改进基础玻璃的热稳定性.     

Densification Energy during Nanoindentation of Silica Glass

Load/unload displacement curves at room temperature (humidity 49%) for silica glass have been measured in the penetration range of 0.5–1.2 μm using a Vickers nanoindentation technique (load/unload speed 50 mN/s). Deformation energies have been estimated for the first time. The universal (dynamic) hardness, H _u, and elastic recovery, E _R, at the penetration depth, h _t, of 1.0 μm are H _u= 4.1 GPa and E _R= 0.7. The following energies for total deformation, U _t, elastic deformation, U _e, and plastic deformation (i.e., densification during loading), U _p, are obtained: U _t=190, U _e=135 and U _p= 55 kJ/mol at h _t= 0.5 μm and U _t= 139, U _e= 96 and U _p= 43 kJ/mol at h _t=1.0 μm. All these deformation energies increase with decreasing penetration depth. It is found that plastic deformation energies of 38–55 kJ/mol for 0.5 < h _t < 1.2 μm are very close to the activation energy (46–54 kJ/mol) for the recovery of densification in silica glass, but are very small compared with the single bond strength (443 kJ/mol for Si—O bond) of SiO₂.     

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.     

PBT/碱硼基空心玻璃微珠复合材料的制备及性能

采用共混与注塑工艺制备出聚对苯二甲酸丁二酯(PBT)/碱硼基空心玻璃微珠复合材料。通过高倍偏光显微镜、扫描电子显微镜对材料的结构进行了表征,并重点研究了碱硼基空心玻璃微珠对PBT复合材料的密度和力学性能的影响。结果表明:微珠由于是玻璃质的具有中空结构的正球体材料,具有质轻、粒径互补,合理填补空隙的作用。当微珠添加量达到15%时,PBT复合材料密度明显降低,下降约9%。复合材料拉伸强度和拉伸弹性模量有所增强,分别提高了9.5%和21.49%。复合材料弯曲强度和弯曲弹性模量具有同样的趋势,分别提高了7.0%和21.87%。综合各项强度,在冲击强度合理降低的情况下,微珠HN60最佳添加量为8%。     

混合烧结法在玻璃陶瓷制备中的应用

概述了混合烧结法的分类、致密化机理、影响因素和在玻璃陶瓷制备中的应用.和传统玻璃陶瓷制备工艺相比,混合烧结法的特点在于玻璃陶瓷中的晶体是直接加入或是通过外加晶体和玻璃反应析出而不是从母相玻璃中直接析出,因而对母相玻璃组分要求不十分严格,在直接利用废玻璃制备玻璃陶瓷和复相玻璃陶瓷方面有着独特的优势.本文重点介绍了近年来该工艺在这方面的应用和进展.     

Constrained Densification of Alumina/Zirconia Hybrid Laminates, II: Viscoelastic Stress Computation

To analyze the inhibited densification during sintering and differential shrinkage during cooling of Al₂O₃/ZrO₂symmetric and asymmetric laminates, viscoelastic formulations, in which the viscosity and elastic modulus vary with time, have been developed. The viscoelastic mismatch stresses have been numerically computed over the entire processing cycle, including the heating period, the isothermal period, and the cooling period. The viscosity and free sintering rates that are needed for stress computation have been obtained by modifying the parameters that are measured for a normal isotropic densifying compact using cyclic loading dilatometry. The modification is based on the available sintering models to account for the effect of strain history on compact viscosity and sintering rates. The stress calculation shows that, with the exception of the initial heating period, the viscoelastic stress is identical to the viscous stress that is calculated solely from the strain rate mismatch. Sintering damage in the laminates is shown to occur during densification under conditions where the differential sintering stress is smaller than the intrinsic sintering pressure. The magnitude of residual stress in hybrid laminates on cooling is dependent on the cooling rate, and slower cooling rates are capable of almost completely relaxing the expansion mismatch stress at temperatures of >1200°C.