EFFECT OF TEMPERATURE ON HOMOGENIZING RATE OF SODA-LIME-SILICA GLASS*

Density-spread determinations were made on a series of melts of a soda-lime-silica glass prepared at temperatures ranging from 1232° to 1454°C. for a four-hour period in the absence of furnace refractory and under conditions of minimum convection mixing. A sharp drop in density spread in the range 1232° to 1288°C., a minimum at about 1325°C., and a slowly increasing density spread at temperatures above 1325°C. were observed. The portion of glass responsible for the major part of the density spread was found to be concentrated in the top half of the glass at both 1232° and 1454°C. At the higher temperature, the improvement in the homogeneity of the bottom layer was more marked than that observed in the top layer as compared with the results obtained on the lower-temperature melt. The density spread of the glass in the bottom layer in the case of the high-temperature melt was in the range of that observed for commercial soda-lime-silica glass of good quality. A possible explanation for the observed increase in density spread at higher temperatures (above 1325°) is offered on the basis of more rapid initial segregation during melting at higher temperature as inferred from the density-spread data and from chemical analyses of the glass from the top and bottom portions of melts made at 1232° and 1454°C. Loss in weight of the glass due to volatilization was determined at 1232° and at 1454°C. and was found to amount to less than 0.01% for a four-hour melting period at both temperatures. Moderate mixing, achieved by repeated cracking and remelting of the glass and by melting in a rotating tilted crucible, had a marked effect in lowering the density spread. The data afforded by these experiments lend further emphasis to the view that convection currents in commercial tank operation are highly significant in improving the homogeneity of a soda-lime-silica glass.     

Al2O3的加入对合成莫来石粉烧结性能的影响

采用玻璃相的后消除法以除去合成莫来石粉中的玻璃相,提高莫来石的高温烧结性能。结果表明：地可有效地除去合成莫来石粉中的玻璃相;烧结体的线收缩率与其体积密度、吸水率、显气孔率及抗弯强同步的;较粗大的Ａｌ２Ｏ３的加入,虽避免了贯穿大孔洞的出现,但却影响了烧结体的致密效果,综合分析,认为延长保温时间和加入微细的Ａｌ２Ｏ３,粉可提高其和密结果。     

EFFECT OF IRON OXIDE ON MELTING OF GLASS*

The addition of small amounts of iron oxide (0.1 to 0.2%) to soda-lime-silica glass batches exerts a profound influence in increasing the output of glassmelting tanks as well as in favoring the production of higher quality glass. The color produced by this addition, moreover, is not objectionable for many uses of the ware. The accelerated melting rate probably is the result of a chemical effect of iron oxide in the batch and a physical property possessed by such glass to absorb radiation from the flames more efficiently. Attempts to measure these effects were made by rioting the melting rate of glasses which contain varying additions of iron oxide and by determining the temperature gradient that exists in glass when it is melted in a miniature tank. The presence of iron oxide aids melting and fining in crucible melts at 1200°C., but no effect was observed at higher temperatures. The measurement of temperature gradients in a pot holding 45 lb. of glass and heated by flames passing over the glass surface showed that the temperature gradient increases with iron oxide content.     

Processing of a Silicon-Carbide-Whisker-Reinforced Glass-Ceramic Composite by Microwave Heating

A calcium magnesium aluminosilicate-based glass that contained 10 wt% of silicon carbide whiskers (SiC _w ) as reinforcement was prepared by tape casting, followed by sintering either in a conventional furnace or in a microwave oven. The results were consistent with retardation of glass sintering through whisker bridging. The glass, by itself, was sintered to almost-full density at 750°C for 4 h by conventional furnace sintering; the best sintered composite, with an estimated density of ∼90%, was obtained at 800°C with a dwell time of 4 h. Sintering at a temperature of >800°C did not improve the densification but rather resulted in severe whisker oxidation. A reduced densification rate was observed for the samples that were sintered in nitrogen. By contrast, in the microwave oven, almost-full density for the glass and ∼95% of the theoretical density for the composite were obtainable at 850°C for 15 min, which represented a reduction of ∼10 h of the total processing time and a reduced SiC _w oxidation.     

浅谈玻璃密度在生产控制中的应用

介绍了玻璃密度检验反馈控制生产的原理和实施方案,在生产稳定的情况下,连续一段时间(5月1日至5月31日)逐日对玻璃进行检验,将检验结果绘制成图。根据正态分布原理规定玻璃密度波动的上限和下限,并通过长期对玻璃密度检验结果分析,得出结论:将玻璃密度检验与化验分析结合起来,可起到快速准确控制成分的效果。     

SMC轻量化初步探究

为实现SMC轻量化,通过模压工艺,从原材料选型、配方设计以及工艺过程控制三个方面对轻质SMC(片状模塑料)进行了探究。首先,通过研究不同类型中空玻璃微珠(HGS)对制品比重、光亮度以及弯曲强度的影响发现,VS5500和H40适合作为轻量化SMC轻质填料,制品的设计密度和真实密度比较接近,且力学性能损失较小。其次,通过配方设计,研究了中空微珠用量、增稠剂类型以及增稠剂用量对制品比重的影响。同时研究了玻纤含量和树脂类型对制品力学性能的影响。研究结果表明,轻质SMC的设计密度不能过低,否则制品中HGS的破损比例将会增加。研究发现EK100作为增稠剂,树脂糊前期粘度可以有效控制,后期粘度快速上升,可以有效防止中空微珠相分离的发生。此外,随着玻纤含量从25%增加到30%,制品力学性能呈现增加趋势,弯曲强度从148 MPa增加到172 MPa,但随着玻纤进一步提高,弯曲强度反而出现大幅度衰减,降到140 MPa。通过研究三种不同类型树脂对制品外观和力学性能的影响,使用P18-03树脂压制的制品外观最好,其弯曲强度为172 MPa,满足汽车外饰件力学性能要求。最后,通过工艺过程控制,研究了微珠处理工艺对制品比重的影响。结果表明,烘干处理的HGS可以有效降低树脂糊的水含量,从而保证树脂糊后期粘度可以达到适合模压的窗口。     

Density Phenomena in the Transformation Range of a Borosilicate Crown Glass

The effect of heat-treatment in the transformation range on the density of a borosilicate crown glass was studied by the method of quenched samples. An empirical equation is presented which satisfactorily represents the approach of the density to its equilibrium value at three temperatures. The density-temperature relation in the special case of cooling at a constant rate is discussed theoretically and experimentally. It is shown that if the initial temperature is sufficiently high, the density-temperature relations for different cooling rates are identical except for a displacement along the equilibrium density-temperature line by an amount proportional to the logarithm of the cooling rate. The final density reached after cooling through the entire transformation range is also shown to depend linearly on the logarithm of the rate. The implications of these results are discussed.     

Effects of pyrochlore content on the phase,structure, and properties of uranium-rich glass ceramics

In this study, the effects of the pyrochlore content on the phase, structure, and properties of uranium-rich glass ceramics were studied by modifying the mass ratio of the uranium pyrochlore in the glass ceramics. The results indicate that U has a high occupancy rate of approximately 0.7 f.u. at the A position of pyrochlore, and the crystal pyrochlore phase in the glass matrix can increase or decrease according to the U amount in the waste. Specifically, at a high occupancy rate and crystallization amount, the U loads reach 20 wt% in the sample, which exceeds the reported 16 wt% maximal U loads of pyrochlore-based glass ceramics. Furthermore, all the samples have excellent mechanical properties and chemical stabilities. The bulk density of each sample is more than 90% the theoretical density, which is 10–20% higher than those of the glass ceramics prepared by pressure sintering. Moreover, the Vickers hardness values of all samples exceed 6 GPa, and the U leaching rate after 21 days is only 6.7 × 10⁻⁵ g m⁻² d⁻¹, which is an order of magnitude lower than those of brannerite glass ceramics under equal leaching conditions.     

玻璃纤维表面的聚甲基丙烯酸甲酯接枝

本文用臭氧对表面涂有ＭＡＣ试剂的玻璃纤维进行了处理，使玻纤表面产生活性中心，引发甲基丙烯酸甲酯在玻璃纤维表面上接枝聚合，接枝纤维的密度减小，对水的浸润性下降，红外光谱及扫描电镜观察证明玻璃纤维表面上有聚甲基丙烯酸存在。     

Electrophoretic deposition of bioactive glass nanopowders on magnesium based alloy for biomedical applications

To slow down the initial biodegradation rate of magnesium (Mg) alloy, crystalline nano-sized bioactive glass coating was used to deposit on micro-arc oxidized AZ91 samples via electrophoretic deposition (EPD). Zeta potential and conductivity of the bioactive glass suspension were characterized at various pH values to identify the most stable dispersion conditions. The bone-bonding properties of bioactive glass coated samples were evaluated in terms of apatite-forming ability during the immersion in simulated body fluid (SBF) solution. Results revealed that the ability to form a bioactive glass coating via EPD was influenced by the degree of its crystalline phase composition. Moreover, the potentiodynamic polarization tests recorded significant drops in corrosion current density and corrosion rate of the coated samples which implies a good level of corrosion protective behavior. These preliminary results show that this process will enable the development of Mg implants in the later stage of bone healing.     

Drop impact and agglomeration under static powder bed conditions

The influence of impact conditions (reported in terms of Weber and Reynolds numbers) on nucleus formation was studied for single drops striking a static glass bead bed. Results from high speed images showed that the nucleation rate is not influenced by liquid physical properties (density, surface tension, viscosity) for drops that spread significantly (30 < We < 233). Results also showed that nucleus size is determined by how much liquid penetrates into the bed during drop spreading, so does depend on surface tension and liquid density. A corresponding analytical model, derived from first principles, predicts nucleus size to with 1.5% using only liquid physical and powder bed properties, plus the experimentally measured drop spreading behavior. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Effect of water on the transmittance of glass plates with eroded surfaces

The corrosion is a chemical phenomenon which can affect the quality of a glass surface, since the glass can fail as a result of its continuous exposure to a corrosive environment. If a glass surface is put into contact with water or with any aqueous solution, it may chemically react with this medium and this chemical exchange may spread all over the surface of the glass, hence causing some undesirable effects, particularly a change in mechanical strength as well as the transmittance.Therefore, the objective of this work was to study the effect of water attacks on the transmittance of glass plates, which have been damaged by sand and then immersed in water at different temperatures and for different immersion times.     

超细连续玻璃纤维生产技术

介绍了超细连续玻璃纤维生产技术发展概况,对采用代铂坩埚法、多排孔超细玻璃纤维成型的关键技术环节进行了分析讨论。采用该技术可以生产高线密度超细玻璃纤维,主要性能可达到国外同类产品的水平,满足了膜结构材料基材的使用要求。     

玻璃纤维质量对FRP质量的影响

介绍了聚合物基复合材料的基本概念,增强材料,包括玻璃纤维、碳纤维及芳纶纤维的定义,特点,生产厂家:详细介绍了玻璃纤维的外观特性、密度、抗拉强度、弹性模量、柔性(脆性)、化学稳定性;从化学分析、含水率、浸润剂、纱线线密度、纱线拉伸断裂强力、纱线硬挺度、短切性、分散性、纱线悬垂度、成带性、单位面积质量均匀性、浸透速率、苯乙烯溶解度等方面,阐述了玻璃纤维质量对FRP质量的影响。     

CHANGES OF PROPERTIES OF GLASS RESULTING FROM CHANGES OF COMPOSITION *

Equations are given for the calculation of changes of density, refractive index, and other optical constants produced by the addition of a known relative weight of a given component to a base glass. Corresponding equations for the substitution of one component for another are also given. Values are computed and listed for the initial fractional rate of change of refractive index (n_D) when various components are added to (a) pure SiO₂ and (b) a sodium silicate glass containing 50% of Na₂O by weight.     

Effect of Crystallization on the Auger Electron Signal Decay in an Li2O·2SiO2 Glass and Glass-Ceramic

Problems associated with Auger analysis of glasses are well recognized. When an electron beam impinges on the surface of a glass specimen, the Auger signal produced by the alkali species decreases with exposure time. The rate at which the signal decays depends on the glass composition, beam current density, accelerating potential of the primary beam, and substrate temperature, all of which must be carefully controlled to obtain a reliable analysis. A similar decay of the alkali Auger signal is observed for glass-ceramic systems. The rate of decay for the crystalline phase is different from that for the glass and depends on the extent of crystallization. This behavior may provide a basis for using Auger electron spectroscopy for microstructural as well as compositional analysis.     

环氧树脂复合泡沫材料的制备研究

以缩水甘油酯环氧树脂(EP)、酸酐固化剂和空心玻璃微珠为主要原料,通过添加一定的活性稀释剂,高温固化制备了EP复合泡沫材料。研究了空心玻璃微珠的表面改性对复合泡沫材料性能的影响。结果表明,复合泡沫材料性能与空心玻璃微珠的表面性能密切相关,当EP/固化剂/稀释剂的质量比为100/120/15、KH-560改性的空心玻璃微珠用量为30份时,所制备的复合泡沫材料密度为0.826 g/cm3,压缩强度达115.8 MPa,比强度为140.2。     

EFFECT OF STEPWISE CHANGE OF DRYING RATE ON MICROSTRUCTURE EVOLUTION IN POLYMER FILMS

The effect of the drying rate of the solvent on microstructure evolution in thin films of immiscible polystyrene/polycarbonate blends was investigated by applying a stepwise change in air velocity. The polymer blend was dissolved in tetrahydrofuran and cast on a glass substrate to form a thin liquid film. The drying rate of the solvent was measured by a gravimetric technique, and the phase-separated structure in the film was observed by optical microscopy. The results indicated that cellular structures of droplet arrays were formed in the phases evolved primarily during the early stage of drying, and the droplets then coalesced in the intermediate stage to form bigger droplets. The size of the first evolved phase decreased with increasing time at a high drying rate, whereas larger droplets were obtained with longer high drying rate regimes. These results suggested that the droplets were induced by secondary phase separation which was strongly affected by the drying rate of the solvent.     

粉煤灰制备微晶玻璃组织与性能的研究

本文利用粉煤灰与石英砂为主要原料制备不同成分的微晶玻璃,并进行核化、晶化。利用扫描电镜对核化、晶化的微晶玻璃进行组织观察,利用硬度计对其硬度测定并对其密度进行测量。研究表明,通过核化、晶化后的微晶玻璃的硬度、密度均升高。当粉煤灰含量较高时,析出网状的晶体组织,并且其在晶化后的硬度增加较少。但当有晶核剂二氧化钛大于5%时,无网状组织析出,且其在晶化后硬度明显提高。     

EFFECT OF STEPWISE CHANGE OF DRYING RATE ON MICROSTRUCTURE EVOLUTION IN POLYMER FILMS

The effect of the drying rate of the solvent on microstructure evolution in thin films of immiscible polystyrene/polycarbonate blends was investigated by applying a stepwise change in air velocity. The polymer blend was dissolved in tetrahydrofuran and cast on a glass substrate to form a thin liquid film. The drying rate of the solvent was measured by a gravimetric technique, and the phase-separated structure in the film was observed by optical microscopy. The results indicated that cellular structures of droplet arrays were formed in the phases evolved primarily during the early stage of drying, and the droplets then coalesced in the intermediate stage to form bigger droplets. The size of the first evolved phase decreased with increasing time at a high drying rate, whereas larger droplets were obtained with longer high drying rate regimes. These results suggested that the droplets were induced by secondary phase separation which was strongly affected by the drying rate of the solvent.