SiO2-A12O3-MgO玻璃纤维结构与性能-MgO/(Li2O+B2O3)的影响

以不同含量的氧化锂、氧化硼、氧化镁成分的SiO_2-A1_2O_3-MgO高强(HS)玻璃为研究对象,测试了HS玻璃纤维密度、纤维新生态强度和模量,以及浸胶纱的拉伸强度和模量。采用高温粘度旋转仪、梯度炉以及红外光谱(IR)、核磁共振(NMR)等方法,研究了玻璃中不同比例的MgO/(Li_2O+B2O3)对高强玻璃结构和性能的影响。玻璃成分中SiO_2和Al_2O_3含量相近,增大Li_2O和B2O3含量替代MgO含量可以使玻璃的低温粘度和液相温度均降低,而增加MgO含量则提高了离子堆积密度和玻璃纤维的模量。红外光谱及核磁共振分析表明,HS高强玻璃的结构主要由硅氧四面体[SiO_4]和铝氧四面体[AlO_4]构成。在玻璃结构中,增加Li_2O和B2O3含量可提供的游离氧可使更多的Al~(3+)形成[AlO_4]而进入玻璃网络。相应地,增加MgO含量,提高MgO/(Li_2O+B_2O_3)比例,增加了网络断键和无序度,但增大了断网间的集合程度,有利于玻璃模量的提升。研究表明提高玻璃中SiO_2含量或在玻璃中加入Li_2O,有利于SiO_2-A12O3-MgO系统玻璃纤维强度的提升。     

Al2O3/SiO2对铝硼硅酸盐玻璃结构与性能的影响

采用高温熔融法制备了铝硼硅酸盐玻璃。通过改变玻璃组成中Al₂O₃/SiO₂比,研究了玻璃组成对玻璃性能的影响。通过光电子能谱(XPS)和核磁共振波谱(NMR)分析了玻璃的结构。结果显示,在Al离子多的玻璃中,Al离子主要形成[AlO₄]结构和少量五配位[AlO₅]、六配位铝[AlO₆]结构,Si离子主要形成Q4结构;在Si离子多的玻璃中,Al离子主要形成[AlO₄]结构,Si离子主要形成Q⁴和Q³结构。随着Al₂O₃/SiO₂比的增大,玻璃中桥氧(BO)数减少,形成[BO₄]和[BO₃]构成的硼氧环结构。这些玻璃结构的变化导致玻璃的热膨胀系数、玻璃转变温度和玻璃软化温度随着Al₂O₃/SiO₂比的改变而变化。     

CaO含量对镧硼硅酸盐玻璃陶瓷晶相和化学稳定性的影响

采用熔融冷却法制备了Na₂O-CaO-La₂O₃-B₂O₃-SiO₂玻璃,经热处理获得了硅酸盐氧基磷灰石硼硅酸盐玻璃陶瓷,并采用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、差示扫描量热法(DSC)、产品一致性试验(PCT)法等方法探究了CaO取代SiO₂对该硼硅酸盐玻璃陶瓷物相、微观结构和化学稳定性的影响规律。结果显示:随着CaO含量增加,硅酸盐氧基磷灰石晶相衍射峰增强,其他晶相的衍射峰减弱直至消失,当CaO摩尔分数为15%时获得只含CaLa₄(SiO₄)₃O晶相的玻璃陶瓷样品;CaO含量会对玻璃陶瓷的晶相种类和晶体形状、大小、分布产生影响,CaO含量变化会造成陶瓷相晶体发生团簇和长大;采用PCT法浸泡28 d后,所有样品关于Si、Ca、La三种元素的归一化浸出率(g·m^-2·d^-1)均保持在10^-3数量级以下,表明其具有优异的化学稳定性,且CaO摩尔分数为15%的玻璃陶瓷样品化学稳定性最优异。研究结果表明,硅酸盐氧基磷灰石硼硅酸盐玻璃陶瓷是固化富La和某些锕系元素高放废物的潜在基材。     

MoO3对玄武岩玻璃结构及性能的影响

三氧化钼在硼硅酸盐玻璃系统中的溶解度非常低,其在核废料玻璃中的过量存在可导致易溶“黄相”的形成。本实验以天然玄武岩制备的玄武岩玻璃为基体,掺入不同含量的MoO₃制备玻璃固化体。采用X射线衍射分析、场发射扫描电子显微镜等测试手段对不同条件制备的玻璃固化体进行表征,研究了MoO₃添加量对玻璃固化体微观形貌、理化性能、化学稳定性的影响。结果表明:MoO₃的大量引入将使玄武岩玻璃析出CaMoO₄。随着MoO₃添加量增加,玻璃固化体Tg下降,密度上升。其钼酸盐最大溶解度为5.5%(质量分数),高于硼硅酸盐玻璃系统,此时玻璃化转变温度、密度分别为619℃、2.70 g/cm²。玄武岩玻璃富含铝,通过对硼硅酸盐玻璃和玄武岩玻璃成分的对比分析,这是其具有优异钼酸盐溶解度的主要原因,玄武岩玻璃固化体28天的浸出液Mo浸出率为8.5×10^-6 g/(m²·d),与广泛使用的硼硅酸盐玻璃相当。     

PbO-Al_2O_3-B_2O_3系统玻璃的结构与性质

木文研究了 PbO-Al_2O_3-B_2O_3系统玻璃的形成范围和热、电性质。结果表明:Ph~(2 )为该系统的龟导载流子,玻璃的电导率主要取决于铅离子浓度、结构状态及网络的连续性,而热性质则与B~(3 )的配位数、结构网络的紧密性有关。 实验结果还表明:氧化硼的两种配位结构[BO_3]和[BO_4],主要取决于系统中能提供游离氧量的PbO以及能优先夺取游离氧的Al~(3 )浓度。当组成中PbO/Al_2O_3>1时,铝呈[AlO_4]存在,当玻璃中PbO含量高时,PbO也能作为玻璃形成物进入结构网络。 该系统玻璃因具有高绝缘性、低熔化温度,已制成一系列低熔封接玻璃用于电子器件中。     

硅硼比对镁铝硼硅酸盐玻璃结构、化学稳定性和介电性能的影响

采用熔融冷却的方法制备了镁铝硼硅玻璃。研究了SiO_2取代B_2O_3对玻璃结构、化学稳定性和介电性能的影响。傅里叶变换红外光谱(FTIR)结果表明,随着SiO_2/B_2O_3比的增大,玻璃网络结构中桥氧增多,非桥氧减少。镁铝硼硅酸盐玻璃的耐酸侵蚀能力随SiO_2/B_2O_3比的增大而增强,而耐碱侵蚀的能力则变差。随SiO_2/B_2O_3比的增大介电常数逐渐增大。当SiO_2/B_2O_3摩尔比为2.08时,玻璃具有最小的介电常数值4.9。SiO_2/B_2O_3比为3.11时,玻璃的介电损耗出现最小值。     

含CuO的Na_2O-B_2O_3-SiO_2玻璃的Raman光谱

本文借助Raman光谱研究了含CuO的Na_2O-B_2O_3-SiO_2 玻璃的结构。分析表明如下:(1)当Na_2O/B_2O_3≤0.4、SiO_2/B_2O_3≤0.6时,玻璃网络由四硼酸盐、[SiO_4]、二硼酸盐基团以及少量的硼氧环构成。玻璃中的氧离子都是桥氧离子。四配位硼的份数随 Na_2/B_2O_3 比增加而增加。(2)当Na_2O/B_2O_3=0.5、SiO_2/B_2O_3=1时,玻璃网络开始出现非桥氧(NBO)离子。直到Na_2O/B_2O_3=0.64、SiO_2/B_2O_3=1.69,存在于玻璃中的基团是二硼酸盐、[SiO_4]、环型偏硼酸盐和带一个非桥氧的[SiO_4](Si—O~-)。NBO离子的数目似乎随Na_2/B_2O_3 比增加而增加。四配位硼的份数在达到极大值后开始下降。(3)当Na_2O/B_2O_3≥0.8、SiO_2/B_2O_3≥2.43时,存在于玻璃中的基团是 Si—O~-、环型偏硼酸盐和[SiO_4」。随Na_2O/B_2O_3比增加,四配位硼的份数下降,而NBO离子的数目则增加、没有(BSiO_4O_(10))~-单元和焦硼酸盐基团形成的指示。(4)玻璃中的一部分硼离子以游离的[BO_3]和[BO_4]单元存在。(5)少量CuO的存在并没引起 Na_2O-B_2O_3-SiO_2 三元系统玻璃的 Raman 谱的重大改变。(6)Na_2O或Na_2O+CuO 全部被硼酸盐基团所吸引,直到Na_2O/B_2O_3或(Na_2O+CuO)/B_2O_3≥0.5时,才共享于硼酸盐和硅酸盐基团之间。     

掺铝钙钛锆石基玻璃陶瓷的结构和抗浸出性能

采用熔融–热处理工艺制备钙钛锆石–钡硼硅酸盐玻璃陶瓷固化体,研究了不同Al_2O_3含量对玻璃陶瓷中玻璃网络体、晶相和显微结构的影响,用产品一致性测试法(PCT法)对玻璃陶瓷固化体的抗浸出性能进行评价。结果表明:随着Al_2O_3含量的增加,更多的Al~(3+)和自由氧形成[AlO_4],使[BO_4]相对减少,[BO_3]增多。在不含Al_2O_3的样品中,只有钙钛锆石和榍石晶相。当掺入2%(质量分数)Al2O3时,开始出现钛酸钙晶相,其含量随着Al_2O_3含量的增加而增加。当Al2O3含量达到6%时,榍石晶相基本消失,只有条状钙钛锆石和方形钛酸钙晶体。产品一致性测试结果表明:掺入Al_2O_3对玻璃陶瓷固化体抗浸出性能影响不明显,玻璃陶瓷中B、Ca、Nd元素的归一化浸出率(LRB、LRCa、LRNd)在28 d后基本保持不变,其中,LR_B、LR_(Ca)与硼硅酸盐玻璃固化体处于同一数量级[约为10–3 g/(m~2·d)],LRNd[约为10–6 g/(m~2·d)]比硼硅酸盐玻璃固化体低1个数量级。     

Al_2O_3/SiO_2摩尔比对无碱铝硼硅酸盐玻璃黏温特性的影响

用高温熔融法制备了Al_2O_3/SiO_2比变化的无碱铝硼硅酸盐玻璃。固定无碱铝硼硅酸盐玻璃体系中SiO_2与Al_2O_3总量不变,研究了用Al_2O_3替代SiO_2对玻璃的熔化温度、成型温度、退火点、应变点等特征黏度参考点的影响;通过红外光谱和Raman光谱研究其结构变化。结果表明:随着铝硅比n(Al_2O_3/SiO_2)逐渐增加,玻璃网络中非桥氧减少,导致退火点(Ta)和应变点(Tst)不断升高;同时,在高温下,熔化温度(Tm)和成型温度(Tf)呈现下降趋势。     

Tm~(3+)和Dy~(3+)共掺氟氧铝硼硅酸盐玻璃微晶化及白光发射性能

采用高温熔融-淬火/热处理方法在空气气氛中制备了Tm_2O_3和Dy_2O_3共掺氟氧铝硼硅酸盐玻璃及透明微晶玻璃。用转靶多晶X射线衍射仪、荧光分光光度计和热分析仪对玻璃样品进行了表征。结果表明:样品在640～660℃热处理4h和在640℃热处理4～16h可制得透明的含Ba_2LaF_7纳米晶玻璃。增大Tm-Dy共掺浓度并降低La_2O_3浓度时,Ba_2LaF_7析晶倾向降低。此外,热处理析出Ba_2LaF_7微晶相后,样品的Tm_2O_3和Dy_2O_3共掺浓度淬灭点由1%(摩尔分数,下同)提高到了2%。掺杂不同浓度Tm_2O_3和Dy_2O_3时,白光发光色度保持不变。     

Molecular Dynamics Simulations of the Structure and Properties of Low Silica Yttrium Aluminosilicate Glasses

Yttrium aluminosilicate glasses are of technological importance in photonics, nuclear waste disposal, and as a delivery vehicle for radiation therapy. Their structures are also of great interest in glass science to elucidate the principles of glass formation and structures. We provide classical molecular dynamics simulation results of a series of yttrium aluminosilicate glasses with low silica concentration. Detailed structure analyses including coordination number, pair and bond angle distributions, Si–O and Al–O network structures, and primitive ring statistics are reported. It is found that the average aluminum coordination number decreases from 4.7 to 4.2 with increasing silica content from 5 to 20 mol%, while maintaining alumina at 55 mol%. Four-coordinated aluminum ions increase from 40% to 84% in the series and the fraction of edge-sharing alumino-oxygen polyhedra decreases, indicating an increased network former role of aluminum ions with increasing silica content. Physical properties such as elastic constant, bulk modulus, Young's modulus, and Possion's ratio were calculated. The results show a decrease of bulk, Young's, and shear moduli with increasing silica and decreasing yttria contents that is in good agreement with experimental data.     

CaO含量对CBAS玻璃/Al2O3低温共烧陶瓷的影响

本文主要研究了CaO含量对CaO-B₂O₃-Al₂O₃-SiO₂(CBAS)玻璃/Al₂O₃低温共烧陶瓷结构和性能的影响。利用DSC、FTIR、XRD、SEM等测试方法对玻璃和低温共烧陶瓷的结构进行表征与分析。研究结果表明,CaO含量低于40%(质量分数,下同)时,由其引入的游离氧增加破坏了网络结构,降低玻璃黏度。CaO含量为40%及以上时,Ca²⁺与[SiO₄]四面体形成较大的阴离子基团,增大玻璃黏度,提高玻璃化转变温度。CaO会促进CaSiO₃和Ca₂SiO₄的析出和CaSiO₃向Ca₂SiO₄的转变。CaO含量增加导致陶瓷的致密度先增加后减少,晶相尺寸增大,使陶瓷的密度、抗折强度和介电常数先增大后减小。当CaO含量为40%时,样品综合性能最好,密度最大为2.94 g/cm³,抗折强度为153.44 MPa,介电常数为9.69。     

Ionic Conductivity in Sodium–Alkaline Earth–Aluminosilicate Glasses

The effect of alkaline‐earth ions on Na transport in aluminosilicate glasses was studied by measuring ionic conductivity for a systematic compositional series of Na₂O–RO–Al₂O₃–SiO₂ glasses (R=Mg, Ca, Sr, Ba). The Na transport in aluminosilicate glass could be affected by compositional changes in aluminum coordination and nonbridging oxygen as well as physical properties such as dielectric constant, shear modulus, and ionic packing factor. Through careful experimental designs and measurements, the main determinants among these parameters were identified. ²⁷Al MAS‐NMR indicated that all aluminum species contained in these glasses are four‐coordinated. The activation energy for ion conductivity decreased with increasing aluminum content and decreasing ionic radii of the alkaline‐earth ion in the region where [Al] < [Na]. When the aluminum content exceeded the sodium content ([Al] > [Na]), the composition dependence of the activation energy depended on the specific alkaline earth. These results are explained based on variations in free volume and dielectric constant caused by structural changes around the AlO₄ charge compensation sites. These structure changes occur in response to the smaller size and higher field strength of the alkaline‐earth ions, and are most prevalent in the compositions which require bridging of two AlO₄ sites by the alkaline‐earth ion for charge compensation.     

Cation Effects on Anion Distributions in Aluminophosphate Glasses

Alkali aluminophosphate glasses, including those in the system x Al₂O₃·(1− x )CsPO₃ (0 ≤ x ≤ 0.25), were examined by high-performance liquid chromatography (HPLC), infrared (IR), and ²⁷Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopies. Phosphate anions become progressively shorter with the addition of alumina to a metaphosphate glass. Al³⁺ ions are initially incorporated into the structure in octahedral sites, but the average Al coordination number (CN) decreases with increasing alumina content and tetrahedral species are the preferred moiety when [O]/[P] > 3.5. Al[4] sites appear to be associated with monophosphate (Q⁰) anions. The role of modifier size on aluminophosphate structure is investigated. At low alumina content (<15 mol%), the disproportionation of pyrophosphate anions into triphosphate and orthophosphate anions is responsible for the lower average Al CN of cesium aluminophosphate glasses compared with sodium aluminophosphate glasses.     

CaO含量对铝硼硅玻璃理化性能的影响与机理

以SiO2、B2O3、Al2O3及碱土金属氧化物(MgO、CaO、SrO)为原料,利用高温熔融法制备无碱铝硼硅玻璃。研究不同CaO含量对无碱铝硼硅玻璃性能和结构影响作用规律。对玻璃进行了热综合分析(DSC)、耐化学稳定性和密度的性能测试,通过红外光谱(FTIR)和X射线光电子能谱(XPS)对玻璃试样进行网络结构分析。研究表明,玻璃的析晶区间面积随着CaO含量的增加,由3.7 J/g升高到15.03 J/g,[AlO6]和[BO4]的出现会导致玻璃网络结构疏松,玻璃的析晶倾向增强;玻璃的被酸侵蚀由3.6817 mg/cm2增加到4.2609 mg/cm2,玻璃被碱侵蚀由1.4199 mg/cm2降低到1.0907 mg/cm2,碱侵蚀的过程中生成的一层硅酸钙薄膜阻碍了反应的进行;随着CaO含量的增加,玻璃中的非桥氧含量增加,会促使[AlO4]向[AlO6]转变,CaO含量继续增加还会使[BO3]向[BO4]转变。     

Role of MgO in lowering glass transition temperature and increasing hardness of lithium silicate glass and glass-ceramics

The effect of variation of MgO (1.5, 4.5 and 7.5 mol%) content on glass structure, crystallization behavior, microstructure and mechanical properties in a Li₂O–K₂O–Na₂O–CaO–MgO–ZrO₂–Al₂O₃–P₂O₅–SiO₂ glass system has been reported here. Increased amount of MgO enhanced the participation of Al₂O₃ as a glass network former along with [SiO₄] tetrahedra, reducing the amount of non-bridging oxygen (NBO) and increasing bridging oxygen (BO) amount in glass. The increased BO in glass resulted in a polymerized glass structure which suppressed the crystallization and subsequently increased the crystallization temperature, bulk density, nano hardness, elastic modulus in the glasses as well as the corresponding glass-ceramics. MgO addition caused phase separation in higher MgO (7.5 mol%) containing glass system which resulted in larger crystals. The nano hardness (～10 GPa) and elastic modulus (～127 GPa) values were found to be on a much higher side in 7.5 mol% MgO containing glass-ceramics as compared to lower MgO containing glass-ceramics.     

TiO2对CaO-Al2O3-SiO2玻璃结构和性能的影响

采用DTA、IR方法研究TiO2对CaO-Al2O3-SiO2玻璃体系结构的影响。DTA分析结果表明,随氧化钛质量分数的变化,玻璃转变温度Tg呈现先升高后降低的趋势;析晶放热峰值温度Tp则逐渐降低。IR分析表明,少量的Ti4+的引入,有助于Al3+进入玻璃网络中。当氧化钛质量分数超过4%时,Ti4+以[TiO4]的形式进入玻璃网络,使网络结构加强;当氧化钛质量分数达到8%时,出现六配位状态的[TiO6]8-。随着氧化钛质量分数的增加,密度逐渐增大;化学稳定性先降低后升高,在一定范围内,引入TiO2能提高玻璃耐碱性。     

Oxidation–Reduction Equilibrium in Copper Phosphate Glass Melted in Air

Copper phosphate glasses with 40, 50, and 60 mol% CuO in batch were melted in air at 1000°, 1100°, and 1200°C using quartz or alumina crucibles, and the [Cu²⁺]/[Cu_total] ratio variations with melting time were measured. Glasses were oxidized during melting and reached equilibrium [Cu²⁺]/[Cu_total] ratios which were independent of melting temperature and identical for the 40 and 50 mol% CuO content glasses. Structural considerations seemed to have determined oxidation-reduction equilibrium rather than an equilibrium redox reaction. Also, the effects of crucible type on the oxidation-reduction balance were examined. It was found that a quartz crucible is more inert and has less effect on the oxidation-reduction equilibrium of glass than an alumina crucible. Crucible contamination and phosphorus vaporization were found to diminish as the CuO content in the batch was increased.     

BaO-TiO2-SiO2系统结构、玻璃形成能力及析晶性能

BaO-TiO2-SiO2系统玻璃具有高折射率和好红外透过性等优异性能特点.在选定组成范围内,采用传统熔融法制备玻璃,通过平板淬冷法进行成形.采用XRD,DSC,RAMAN光谱和SEM,探讨了BaO-TiO2-SiO2系统的玻璃形成能力、析晶性能及玻璃结构变化规律.研究结果表明:随着SiO2从5mol%~20mol%逐渐增加,成玻能力逐渐增强,SiO2≥20mol%开始得到完全非晶态玻璃.等SiO2含量下,随TiO2含量的增加,玻璃转变温度逐渐升高.SiO2含量等于15mol%时,随着TiO2含量的增加,[TiO6]先增加后减少,TiO2含量为45mol%时,[TiO6]的Ti-O振动峰出现,60mol%时,[TiO6]的Ti-O振动峰消失,[TiO4]在TiO2的含量为40mol%~50mol%时存在,Ba2+对Si-O骨架具有破坏作用.