混合碱土金属氧化物对硼硅酸盐玻璃热膨胀系数的影响

研究了4种碱土金属氧化物(MgO、CaO、SrO、BaO)替代Na2O后对硼硅酸盐玻璃热膨胀系数和软化温度的影响,对比分析了二元和三元混合碱土对玻璃热膨胀性能的影响,通过阿本法计算了玻璃的热膨胀系数并与实测值进行了比较。研究结果表明:碱金属与碱土金属氧化物形成的"混合碱-碱土效应"使得玻璃的膨胀软化温度显著提高;三元混合碱土的性能比二元混合碱土的性能好;通过阿本法计算的热膨胀系数值,含有2种碱土的玻璃的计算值小于实测值,而含有3种碱土的玻璃的计算值明显大于实测值。     

混合碱效应对CBN磨具用玻璃结合剂性能的影响

调节结合剂配方,改善结合剂性能是提高CBN磨具使用性能的一个重要途径.本文研究了Na2O-Li2O、Na2O-K2O、Na2O-Li2O-K2O不同混合碱对CBN磨具用硼铝硅酸盐玻璃结合剂熔融温度、抗折强度、矿物组成、热膨胀系数及热膨胀软化温度的影响.结果表明,在R2O总量为20%不变的情况下, 调节碱金属氧化物的组成及比例可使玻璃结合剂的某些性能出现明显的"混合碱效应":抗折强度从40.37 MPa增至51.89 MPa,热膨胀系数从10.32×10-6/℃降至 8.40×10-6/℃, 添加三元混合碱系列的玻璃结合剂性能比添加二元混合碱系列的性能更好.     

碱土金属氧化物含量对模拟高放废液玻璃固化体析晶行为的影响

以硼硅酸盐玻璃作为基础玻璃基材,通过熔融法制备了含16%(质量分数)模拟高放废液的玻璃固化体,探究了碱土金属氧化物含量对玻璃固化体析晶行为的影响,以期在保证玻璃固化体性能要求的前提下,通过控制碱土金属氧化物的含量抑制玻璃固化体的析晶倾向。结果显示:碱土金属氧化物(CaO+MgO+BaO)含量在7%~19%(质量分数)时,玻璃固化体析晶上限温度和析晶率随碱土金属氧化物含量的降低而逐渐降低;玻璃网络聚合度的增加能够显著增强玻璃固化体的抗析晶性能,当碱土金属氧化物含量低于11%(质量分数)时玻璃固化体中硫酸盐的溶解度明显下降。基于包容0.7%(质量分数)SO₃的要求,碱土金属氧化物含量适宜组成应控制在11%(质量分数)以上。     

化学成分对铁钛着色医药玻璃耐水性能的影响研究

选取以铁钛着色的棕色低硼硅医药玻璃为基础成分,分别探索碱金属氧化物和氧化铝与氧化硼对玻璃耐水性的影响。研究发现:当ω(Na2O+K2O+SiO2)=80%,ω(Na2O+K2O)≤14%时,耐水性可达到1级,碱金属离子是玻璃耐水性变差的关键性因素;当ω(A l2O3+B2O3+SiO2)=80%,选取ω(Na2O)=10.8%,ω(K2O)=2.2%时,随A l2O3和B2O3总量的提高,耐水是不断地提高,当ω(A l2O3+B2O3)≥6%即可达到耐水性1级,证明A l2O3和B2O3是耐水性提高的关键性因素。     

Na2O含量对日用玻璃贴花装饰用无铅熔剂性能的影响

以R2O-ZnO-B2O3-SiO2(ZBS)体系为日用玻璃贴花装饰用无铅熔剂的基础配方,通过调整Na2O的含量,探讨Na2O含量对熔剂性能的影响。采用热膨胀仪、光泽度仪、SEM及FT-IR对样品的热膨胀系数、光泽度及显微结构进行表征,分析熔剂组成-结构-性能之间的关系和变化规律。结果表明:样品的热膨胀系数α随Na2O的增加先增大后减小;光泽度、耐碱性随Na2O的增加而增大;耐酸性、彩烤温度随Na2O的增加而降低。当w(Na2O)=9.07%时,ZBS系统熔剂的α与玻璃基板的匹配性最好,光泽度能达到82,耐酸性最好,耐碱性甚至可以达到商业标准的4～5级。     

基于化学组成的龙泉窑粉青和梅子青釉呈色研究

以龙泉青釉为基础，首先根据氧化铁的含量不同设计粉青和梅子青两大系列釉，再通过改变石灰石、滑石、钾长石、钠长石的相对含量，采用正交配釉法总共配制了39种釉，分别施于龙泉弟窑白胎上进行烧制实验，通过观察烧成制品釉的呈色，推论出釉的化学组成即各氧化物对釉呈色的影响结果为：釉中氧化铁含量决定了釉的色调，即釉色的深浅浓淡，而还原比例决定了釉的颜色，即黄绿青兰色；对比碱金属和碱土金属氧化物，碱土金属氧化物有利于铁保持低价态，使釉呈蓝青色，碱金属氧化物有利于铁保持高价态，使釉呈黄绿色；对于碱金属氧化物而言，当碱金属含量低时，氧化钾使釉呈青中带蓝色，而氧化钠使釉呈蓝色中泛黄色，当碱金属含量高时，氧化钠使釉呈青中带蓝色，而氧化钾使釉呈青中带黄色；对于碱土金属而言，氧化钙有利于铁保持低价态，使釉呈蓝青色，而氧化镁则使釉的色调变浅，颜色变青白色。     

R2O对ZnO-Sb2O3-P2O5低熔玻璃性能的影响

借助IR、DTA等研究了碱金属氧化物R2O(R=Li,Na,K)对ZnO-Sb2O3-P2O5低熔玻璃结构及性能的影响。结果表明:不同种类碱金属氧化物的加入对玻璃的磷酸盐网络结构无明显影响,但K2O的引入提高了玻璃的转变温度(Tg)、软化温度(Ts)、析晶倾向和耐水性。R2O取代ZnO后破坏了玻璃的网络结构,导致玻璃的Tg及Ts温度和耐水性的降低,增加了玻璃的析晶倾向。在总碱量不变的条件下,借助混合碱效应,调节Li2O/(Li2O Na2O)摩尔比能够获得Tg及Ts温度更低的玻璃,同时耐水性也有所提高。对玻璃膨胀系数(α)的影响依次为K2O>Na2O>Li2O,且随R2O含量的增加而增加。此外混合碱效应对α的变化无明显影响。     

高碱煤中碱金属及氯元素析出特性

煤灰的理化特性与灰化温度密切相关,试验研究了不同灰化温度下高碱煤中碱/碱土金属以及氯元素的析出特性,分别采用X射线荧光光谱分析(XRF)与电感耦合等离子光谱分析(ICP-OES)对样品成分进行分析,并对结果进行对比。结果表明,煤的灰分和煤灰中的碱金属含量随灰化温度的升高而降低,碱土金属含量变化不大;Cl元素析出温度低于500℃,且在815℃前基本完全析出;Na元素的析出特性与煤中Cl元素含量密切相关;低温灰化造成高灰分煤种碳燃尽困难,但对碱金属测量造成的相对误差有限,ICP-OES对于元素含量测试的结果低于XRF,但2种测试方法获得的碱/碱土金属元素含量随灰化温度的变化趋势一致,前者具有更高精度,因而推荐采用ICP-OES测试方法测量碱/碱土金属的含量。     

碱激发粉煤灰/矿渣复合体系的性能研究

研究了碱激发剂中SiO2与Na2O含量对碱激发粉煤灰/矿渣复合体系凝结时间和抗压强度的影响,并采用扫描电镜对样品的微观形貌进行表征,研究结果表明:碱激发粉煤灰/矿渣的凝结时间在15～705 min总体而言,激发剂中Na2O含量越高(＞4％),样品的凝结时间越长;SiO2含量越高(＞2％),样品的凝结时间越短.激发剂中SiO2含量为4％,Na2O含量为6％时,样品抗压强度增幅最大.扫描电镜(SEM)结果表明,SiO2含量越高,材料结构越致密;当Na2O含量高于6％时,材料结构变松散.颗粒较细,比表面积较大的粉煤灰碱激发活性高,样品的抗压强度也越高.     

K2O对Na2O-Al2O3-B2O3玻璃性质的影响

制备了添加K2O的Na2O—Al2O3-B2O3系统低熔点玻璃,研究了玻璃的转变温度（Tg）、热膨胀系数（仅）和玻璃的红外光谱,表明随着K20含量的增加Na2O—AlO3-B2O3玻璃熔化温度、转变温度也降低,添加K20玻璃的热膨胀系数较大,在近红外区有一水分的吸收带,在中红外区有B—O、A1-O的特征吸收带,玻璃的Tg、仅与玻璃中K2O含量的关系,混合碱效应对玻璃的性能的影响。     

R2O对低熔点硼硅酸盐玻璃性能的影响

R2O-A l2O3-B2O3-SiO2-TiO2-F玻璃系统中在碱金属氧化物R2O(Li2O、Na2O、K2O)总量不变的情况下,通过调节R2O的组成,分别研究了组成变化对玻璃热膨胀系数、化学稳定性和转变温度Tg、软化温度Tf的影响规律。研究表明,R2O组分的调节可以明显降低玻璃的热膨胀系数、酸性失重、转变温度Tg以及软化温度Tf,而对碱性失重影响不大。     

The effect of alkali metal oxide on the properties of borosilicate fireproof glass: Structure,thermal properties,viscosity, chemical stability

The purpose of the current work was to research the effect of alkali metal oxide on the structure, thermal properties, viscosity and chemical stability in the glass system (R₂O–CaO–B₂O₃–SiO₂) systematically. Because the glass would emulsify when Li₂O was added to the glass batch, this article did not discuss Li₂O. The results showed that when the amount of Na₂O was less than 4 mol.%, there was a higher interconnectivity of borate and silicate sub-networks in glass, as more mixed Si–O–B bonds were present in glass. The glass samples exhibited excellent thermal properties and chemical stabilities. As the amount of Na₂O exceeded 4 mol.%, the interconnectivity of borate and silicate sub-networks was weakened. The thermal properties and chemical stabilities of the glass samples were reduced. The connectivity of the silicate sub-network was weakened slightly as the Na/K ratio varied, and the coefficient of thermal expansion (CTE) of the glass samples gradually increased, and the resistance to thermal shock (RTS) value gradually decreased. Moreover, the viscosity of the glass samples decreased with the ratio of Na/Si and Na/K increased.     

混合碱效应对Li2O-Al2O3-SiO2系玻璃结构和热膨胀性能的影响

本文用传统高温熔融法熔制Li₂O-Al₂O₃-SiO₂系高铝玻璃,改变碱金属氧化物n(Li₂O)/n(Na₂O)的摩尔比,运用阿基米德排水法、热膨胀仪、DSC、傅里叶变换红外光谱和拉曼光谱等测试手段和仪器,探究了混合碱金属效应对Li₂O-Al₂O₃-SiO₂系玻璃结构和热膨胀性能的影响。结果显示:随着n(Li₂O)/n(Na₂O)比例增大,混合碱金属效应对Li₂O-Al₂O₃-SiO₂系玻璃的密度和热膨胀系数的影响一致,表现为先增大后减小,当R=0.25(R=n(Li₂O)/[n(Li₂O)+n(Na₂O)],摩尔比)时,出现极值,此时密度达到最大2.447 4 g/cm³,热膨胀系数达到最大7.811 7×10^-6/℃;对玻璃特征温度的影响随着温度的升高而逐渐减弱至消失;对玻璃的析晶能力有一定的提升作用;对玻璃三维骨架结构中的硅氧四面体Qⁿ的影响也各不相同。     

n(B2O3)/n(SiO2)对硼硅酸盐玻璃结构和性能的影响

采用热膨胀仪、扫描电镜和红外光谱仪研究了硼硅酸盐玻璃的结构与性能随n(B2O3)/n(SiO2)和n(B2O3)/n(Na2O)的变化规律,深入探讨了结构对分相、热膨胀系数和膨胀软化温度的影响规律。结果表明:热膨胀系数取决于玻璃中[BO3]、[BO4]和[SiO4]的数量变化;玻璃的转变温度和软化温度主要由SiO2决定;[BO3]对玻璃的分相有着重要的影响;不论n(B2O3)/n(Na2O)比值多少,玻璃结构中均存在[BO3]和被破坏的[SiO4]。     

碱金属氧化物对低介电封接玻璃结构与性能的影响研究

玻璃由于优异的电学性能在电子封接领域的应用越来越广泛。本文以硼铝硅酸盐玻璃为基础玻璃体系,采用高温熔融法制备了低介电封接玻璃。通过拉曼光谱、热膨胀系数测定仪、密度计、弯曲梁低温测试仪、精密阻抗分析仪等对样品性能进行表征,研究了碱金属氧化物对低介电玻璃的结构与性能的影响。研究结果表明:碱金属氧化物R₂O总量保持不变,随着Li₂O取代量的增加,玻璃结构中[BO₃]含量先降低后增加,同时[AlO₄]增加、[AlO₆]降低;玻璃的热膨胀系数先降低后升高,密度变化趋势与之相反,且均在LN-3(Na₂O与Li₂O质量比为1.0:1.0)组出现极值;特征温度先升高后降低,最后Na₂O被完全取代后呈现再次升高的趋势;玻璃介电常数和介电损耗先降低后升高,且混合碱金属玻璃的介电常数和介电损耗均低于单一碱金属玻璃。     

Specific Features of Changes in the Properties of One- and Two-Alkali Borate Glasses Containing Water: III. Thermal Expansion and the Structural and Mechanical Relaxation Parameters of Two-Alkali Borate Glasses

The thermal expansion and stress relaxation in mixed alkali borate glasses containing lithium, sodium, and potassium oxides with a total alkali oxide content of 15 mol % are measured on an inclined quartz dilatometer and a relaxometer. The experimental data obtained are used to determine the thermal expansion coefficients and the structural and mechanical relaxation parameters. No deviations from the additivity are found in the concentration dependences of the thermal expansion coefficient and the calculated parameters determining the width of the spectra of the structural and stress relaxation times. The IR absorption spectra of the studied glasses are recorded in the range of stretching vibrations of hydroxyl groups. Analysis of the IR spectra makes it possible to assume that the content of residual water in the structure of borate glasses affects the manifestation of the mixed alkali effect in the properties of these glasses.     

Effect of Al2O3 addition on the thermal expansion of sodium alkaline-earth silicate glasses: A molecular dynamics study

Coefficient of thermal expansion (CTE) is an important property to consider when utilizing oxide glasses in thermal treatment processes to avoid thermal damage at the interfaces of the glasses with heterogeneous materials. It is thus important to know the effect of additives on CTE for designing glasses. The use of alumina efficiently improves chemical and mechanical durability of oxide glasses while maintaining the functionality and productivity; however, alumina-doping often induces nonlinear variation of CTE. In this work, we therefore tried to investigate the relationship between CTE and the microstructure of sodium alkaline-earth aluminosilicate glasses using classical molecular dynamics (MD) simulations. To accurately model the glasses, we extended a force-matching potential by optimizing the parameter sets for Ca–O, Mg–O, and Na–O pair interactions using Bayesian optimization. The MD simulations reproduced the nonlinear variation of CTE as a function of alumina content, and detailed structural analyses identified inhomogeneous expansion in the glasses. It was found that the nonuniform CTE change at the nanoscale was related to the formation of an alumina-rich region, in which more fivefold-coordinated aluminum exist, when alumina content exceeded Na₂O content. Accordingly, the microstructural change by alumina-doping was identified as the origin of the nonlinear variation in the CTE of the glasses.     

Effects of Na2CO3/K2CO3 on Chemical Looping Combustion Using Fe2O3/Al2O3 as Oxygen Carrier

The performance of the Fe₂O₃/Al₂O₃ oxygen carrier modified by the alkali metals, Na and K, was studied by thermogravimetric analysis and in a laboratory-scale fluidized-bed reactor. Different factors, such as the alkali metal content, the alkali metal type, and the interaction between Na and K, were taken into account. Both Na and K had strong catalytic effects on the conversion of Fe₂O₃. A high K content caused serious agglomeration. Increasing the Na content led to slagging because of the low-melting point solid solution. The possibility of agglomeration and slagging was reduced when Na and K were added together. The oxygen carrier with 1.5 wt % Na and 1.5 wt % K had better combustion efficiency and optimal thermal stability. Na and K could enhance the attrition resistance and prolong the lifetime of the oxygen carriers.     

La2/3Sr1/3MnO3(La1.4Sr1.6Mn2O7)/Ce0.8Gd0.2O2-δ复合阴极的微观结构及热膨胀性能

采用固相反应法制备La2/3Sr1/3MnO3(LSMO3)粉体,用溶胶-凝胶法分别制备La1 4Sr1 6Mn2O7(LSMO7)和Ce0.8Gd0.2O2-δ(CGO)粉体.分别将LSMO3和LSMO7粉体与CGO粉体以1∶1的质量比均匀混合,在300MPa下冷等静压成型,并在1 500℃烧结2 h,制备了LSMO3/CGO和LSMO7/CGO复合阴极材料.研究了2种复合阴极材料的微观结构和热膨胀性能.结果表明:LSMO3/CGO与LSMO7/CGO烧结体在150～1 000℃温度范围内的平均线性热膨胀系数分别为1.52×10-5/K和1.53×10-5/K,与CGO固体电解质具有相近的热膨胀性能.烧结体断面形貌分析表明:LSMO3/CGO复合阴极具有与CGO相似的断面显微结构.     

Thermal Expansion of Alkali Borate Glasses

The thermal expansion behavior of lithium, sodium, potassium, and rubidium borate glasses was measured. The results indicate that the "borate anomaly" in the thermal expansion coefficient occurs at ∼20 mol% alkali oxide. A maximum in the glass transformation and dilatometric softening temperatures also occurs at ∼27 mol% alkali oxide. No evidence for phase separation was observed in this study. These effects are related to the structural changes reported for these glasses by Bray and coworkers.