发泡剂在泡沫玻璃中的应用

泡沫玻璃是一种新型的保温隔热多孔材料,发泡剂是促进配合料产生泡沫从而形成气孔结构的物质,对泡沫玻璃的孔径、孔分布等孔结构有着直接影响.介绍了不同发泡剂的发泡机理及选择方法;评述了发泡剂的种类、掺量和细度对泡沫玻璃孔结构及其性能的影响;讨论了发泡剂种类、掺量及细度的选择与控制原则.     

利用回收平板废玻璃制备泡沫玻璃的研究

泡沫玻璃是一种新型的环境友好型多孔材料,其性能与气孔结构息息相关.本文利用回收的平板玻璃,通过引入石英砂,添加碳酸钙发泡剂,制备了泡沫玻璃,同时对气孔调控进行了研究.研究结果表明,随着碳酸钙发泡剂质量分数的增加,泡沫玻璃的孔径增大,开气孔数量增加,总气孔率增大,泡沫玻璃的保温性能良好.但当发泡剂添加量进一步增加时,泡沫玻璃孔壁变薄,相邻气孔易融合塌陷,致使抗压强度降低.通过引入石英砂提高发泡时熔体的空间骨架强度,可以调节泡沫玻璃中开气孔、闭气孔比例,提升抗压强度,满足不同领域对泡沫玻璃的性能要求,进而拓宽泡沫玻璃应用范围.     

用熔融法固化生活垃圾焚烧灰渣并制备泡沫玻璃

以质量分数为70%的生活垃圾焚烧灰渣为原料,通过添加少量其他玻璃成分调节组成,采用熔融法固化并粉碎得到玻璃态垃圾灰渣。然后以CaCO3为发泡剂,用烧结发泡法制备了性能良好的泡沫玻璃,研究了发泡温度和发泡剂含量对泡沫玻璃气孔结构、表观密度和抗压强度的影响。结果表明:发泡温度和发泡剂含量对该组成泡沫玻璃的气孔结构影响较大;随着温度升高,泡沫玻璃的气孔结构变得均匀,表观密度减小,但过高的温度会导致气体逸出,气孔收缩;在920℃发泡得到的泡沫玻璃具有低的表观密度(0.269g/cm3)和相对较高的抗压强度(2.60MPa);随着发泡剂含量从0.5%增加到2.5%,泡沫玻璃的孔径逐渐增大,表观密度减小,其抗压强度的变化趋势与气孔结构、表观密度是相一致的。     

粉煤灰泡沫玻璃工艺性能的研究

以粉煤灰和废玻璃为主要原料，添加适量发泡剂、助熔剂等制备粉煤灰泡沫玻璃。讨论分析了成型压力和退火制度等工艺过程对泡沫玻璃性能的影响。     

粉煤灰泡沫玻璃的试验研究

以粉煤灰和玻璃粉为主要原料,添加适量的发泡剂、稳泡剂等助剂,可制得粉煤灰泡沫玻璃。通过对制品体积密度、表观密度、开口孔孔隙率、吸水率等性能的测定,分析了发泡剂、粉煤灰掺量对泡沫玻璃性能的影响。实验表明,适量添加粉煤灰和玻璃粉,可制得性能较好的粉煤灰泡沫玻璃。     

碳酸钠对粉煤灰泡沫玻璃性能影响的研究

发泡剂对泡沫玻璃物理力学性能有显著的影响。为了探究碳酸钠掺量对泡沫玻璃性能的影响及成孔机理,以20%粉煤灰和80%玻璃粉为基料,分别采用2%、3%、4%、5%和6%碳酸钠掺量,制备粉煤灰泡沫玻璃,并进行了测定;通过试验研究了碳酸钠掺量对粉煤灰泡沫玻璃的导热系数、表观密度、机械强度及孔隙率等性能指标的影响,并对碳酸钠在泡沫玻璃中的成孔机理进行了分析。当碳酸钠的掺量为5%时,导热系数为0.0735 W/(m·K),达到最小,抗压强度为1.58 MPa,抗折强度为0.75 MPa,表观密度为0.276 g/cm~3,孔隙率为87.7%,此时粉煤灰泡沫玻璃的空隙结构分布相对均匀且以封闭孔为主。泡沫玻璃孔径的大小与碳酸钠的粒径、发泡温度及压强等因素有关。当碳酸钠的粒径一定时,随着气泡内压强的增大,气泡直径减小;当泡内气体的压强一定时,气孔直径随着碳酸钠粒径的增大而增大。     

基于赤泥和硅灰的泡沫玻璃制备及性能研究

以赤泥、硅灰和废玻璃为主要原料,采用“一步法”制备泡沫玻璃.重点研究了原料配比及发泡剂、稳泡剂、助熔剂等因素对泡沫玻璃结构和性能的影响;对比研究了不同制备条件下泡沫玻璃的孔径尺寸、分布特征、表观密度及吸水率等性能变化规律;探索出了赤泥、硅灰基泡沫玻璃较为适宜的原料配比及发泡剂、稳泡剂、助熔剂等改性剂的适宜种类和添加量.研究结果表明,赤泥、硅灰及废玻璃的适宜掺量分别为32.28％、27.72％和40％;匹配性良好的发泡剂、稳泡剂、助熔剂分别为CaCO3、Na3PO4和硼砂,适宜加入量分别为3％、2％和2％.该条件下制备的泡沫玻璃孔径分布均匀、大小适中,表观密度为0.558 g/cm3,吸水率为5.46％,综合性能较好.     

工艺制度对粉煤灰泡沫玻璃性能的影响研究

以废玻璃和粉煤灰为主要原料，并添加发泡剂、助熔剂、稳定剂制备出了粉煤灰泡沫玻璃。通过改变玻璃颗粒、发泡温度、发泡时间等工艺因素，研究了泡沫玻璃的性能与工艺制度变化的关系，分析了影响泡沫玻璃质量的工艺因素。     

影响粉煤灰泡沫玻璃质量的因素研究

本文对发泡剂种类与掺量、发泡温度、发泡时间、烧结温度、烧结时间、粉煤灰细度与掺量、稳定剂种类与掺量对粉煤灰泡沫玻璃质量的影响进行了研究，找出了生产粉煤灰泡沫玻璃的最佳参数，粉煤灰泡沫玻璃性能优良，可作为隔热保温材料的换代产品。     

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.     

梯温炉法确定泡沫玻璃发泡温度的研究

用梯温炉法确定了泡沫玻璃的发泡温度.介绍了梯温炉的结构及原理,根据测量结果绘制了发泡温度与泡径的关系曲线.讨论了发泡温度对泡径的影响,并将测量结果和DTA曲线进行了比较,结果表明,梯温炉法与DTA曲线的实验结果吻合.应用梯温炉法确定泡沫玻璃的发泡温度,准确,直观,简捷,测量结果令人满意.     

多孔微晶玻璃的研制及性能

以废玻璃为主要原料,用V2O5作为成核剂,再加入其它辅助原料制备了多孔微晶玻璃,研究了发泡温度、保温时间等因素对多孔微晶玻璃泡径及性能的影响。结果表明,发泡温度越高,泡径越大,制品密度越小,最佳发泡温度为725℃;保温时间越长,泡径越大,当在725℃保温25min时,析出的晶体有SiO2、Al2SiO5及Na2Ca2(SiO3)3,平均泡径为2.039mm,密度为0.65g.cm-3,热膨胀系数为115.6×10-7℃-1,抗压强度为7.31MPa,抗折强度为5.83MPa。     

泡沫玻璃气泡缺陷与解决方案

泡沫玻璃是一种具有均匀气泡结构的玻璃制品,具有隔热、吸声、防潮、防火等特点的轻质高强建筑材料和装饰材料。泡沫玻璃的生产过程中,经常会遇到气泡结构不均或大气泡等气泡缺陷。本文从气泡的产生机理分析入手,针对具体的气泡缺陷种类,分析产生原因,提出解决方案,更好地实现泡沫玻璃的内在和外观质量。     

影响泡沫玻璃泡径因素的数学分析

在实验的基础上应用数学分析方法,建立了较理想的泡沫玻璃的泡径和发泡剂粒径及发泡温度间的函数关系,对设计泡沫玻璃新品种有一定参考价值。     

水在开孔泡沫铜中的池沸腾传热特性

对常温、大气压下水在开孔泡沫铜中池沸腾的传热特性进行了试验研究,观察了开孔泡沫铜中汽泡的生长特性及其变化规律,并与水在光管加热面的池沸腾特性进行了对比。试验结果表明:水在泡沫铜中池沸腾时,汽泡脱离直径和汽泡脱离频率随热通量的增加而不断增大,泡沫铜对水的池沸腾传热具有很好的强化效果。根据试验结果,得到了水在开孔泡沫铜中池沸腾传热的传热系数拟合关联式,为进一步的研究提供了依据。     

Spontaneous Bubble Formation in Silicate Melts at High Temperatures: II, Effect of Wet Atmospheres and Behavior of Mixed Alkali Glasses

Earlier work with alkali silicates was extended. Time and temperature for originally melting the glass had little influence on bubble or foam formation. Water vapor in the furnace atmosphere lowered foaming temperature considerably. Mixed alkali glasses showed complex and unexpected behavior. Nucleation and growth of foam bubbles as well as foam stability are discussed.     

In-situ X-ray and visual observation of foam morphology and behavior at the batch-melt interface during melting of simulated waste glass

To attain a basic understanding of the primary foam structure and behavior, which affects the heat and mass transfer and the efficiency of the glass melting process, we investigated the primary foam layer under the glass batch floating on molten glass. The primary foam affects mass transfer during batch melting, in turn affecting the melting process. The recently performed direct in-situ three-dimensional X-ray computed tomography of the batch melting in a laboratory-scale melter vessel allowed us to visualize the features of the reacting batch layer and the foam that develops at its bottom, though with an insufficient resolution of images. In this study, we obtained better temporal and spatial resolution using the two-dimensional X-ray radiography and visual observation of the structure and behavior of transient primary foam as it formed and decayed. As soon as the batch was charged onto the melt surface, foam bubbles began to evolve, grow, and coalesce, forming a primary foam layer, 5–10 mm thick, within tens of seconds. This foam layer was sustained by ongoing gas evolving reactions counterbalanced by bubble coalescence into cavities that moved sideways and escaped to the atmosphere. Eventually, the entire remaining batch turned into foam that gradually decayed at the melt surface. The decay rate agreed with literature observations of surface foam produced by secondary foaming.     

HYDRODYNAMIC STUDIES IN FISCHER-TROPSCH DERIVED WAXES IN A BUBBLE COLUMN

Gas hold-up and Sauter mean bubble diameter measurements were made in a 0.051 m diameter by 3 m long glass bubble column in the system, nitrogen-molten wax, with three different waxes (paraffin wax FT-300, Sasol's Arge wax and Mobil's reactor wax). Paraffin wax has a tendency to foam and gas hold-up is a strong function of gas distributor type, temperature and start-up procedure, whereas the reactor waxes do not foam and are much less affected by these variables, In experiments at 265°C with a 1.85 mm single hole orifice plate distributor the gas hold-ups were nearly the same for all three waxes. However, significant differences in Sauter mean bubble diameters were obtained in experiments with different waxes; FT-300 wax produced the smallest Sauter mean bubble diameters whereas Mobil's reactor wax produced the largest bubbles. Addition of 1-octadecanol and octadecanoic acid (up to 10wt%) to the FT-300 paraffin wax caused an increase in gas hold-up and a delay in the foam break-up in runs at 265°C with the 1.85 mm orifice plate distributor.     

Foaming in Glass Melts Produced by Sodium Sulfate Decomposition under Isothermal Conditions

The factors controlling the behavior of foam produced in molten glass by sulfate decomposition are sulfate oversaturation (determined by the initial sulfate concentration, fraction of sulfate dissolved, and melting temperature), bubble nucleation (occurring predominantly on the residual silica grains), and film stability. The connection between the foam generation and variation in melting temperature and silica grain size has been experimentally investigated by observing the melting process in a transparent silica crucible. A generation/release model for the time variation of gas-phase volume retained in molten glass has been developed. The analysis of experimental data using this approach suggests that two forms of sulfate produce foam during melting: (1) sulfate dissolved in melt and (2) sulfate from sulfate-rich melt surrounding sand grains.     

Estimating the Efficiency of an Aerodynamic Foam Breaker

An expression for the jet outflow velocity (dynamic characteristic of the foam breaker) and the related effective diameter of a destructurized foam bubble is derived from the energy balance in the interaction of the gas jet and foam structure. An analysis of the jet outflow hydrodynamics gives an expression for the volumetric injection rate as a performance characteristic of the aerodynamic foam breaker. Relationships between the structural and geometric parameters of the original and broken foams are derived under the assumption that the foam breaks by a cohesive mechanism. The properties of the foam are related to the bubble reduction ratio and the number of foam destruction stages. The stable operating conditions of the hydrodynamic foam breaker are determined by nomography. These conditions depend on the foam breaker design and on the structure and behavior of the foam.