CaO-B2O3-SiO2系低温共烧陶瓷的致密化行为及性能

以CaO-B2O3SiO2(CBS)玻璃粉末为原料.采用流延成形工艺制备了CBS系生料带.生料带在排完胶后可以在775～950℃内烧结.研究了生料带在烧成过程中致密化和晶化行为以及烧成温度对其介电性能和烧结性能的影响.结果表明:烧成样品中的主晶相为β-CaSiO3,850～900℃烧成样品中有少量CaB2O4.在样品烧成过程中,排胶后的CBS玻璃粉末首先烧结致密化,然后才开始晶化,即致密化过程要早于晶化过程,CBS玻璃的析晶倾向于整体析晶, 这有利于CBS玻璃粉末的烧结.由于玻璃中析出晶相与残余玻璃相存在密度差,烧成样品的体积密度随着烧成温度的升高而降低.烧成温度的升高可促使玻璃中晶体析出和长大,且析出晶相具有比CBS玻璃低的相对介电常数(岛),样品的εr随烧成温度的升高呈下降趋势.     

烧结助剂对硼硅钙微晶玻璃结构和介电性能的影响

研究了烧结助剂P2O5和ZnO对CaO-B2O3-SiO2(CBS)玻璃粉末的助烧作用及其对材料的相组成、显微结构和介电性能的影响.结果表明:未添加烧结助剂在1000 ℃烧成的样品晶粒粗大(1～3 μm),且结构疏松.复合添加2%(质量分数,下同)P2O5和0.5%ZnO后,850℃烧成的CBS微晶玻璃中,包含有β-CaSiO3,α-SiO2和CaB2O4 3种晶相,晶粒发育细小均匀,粒径为0.5 μm左右,具有一定量的玻璃相,且结构致密.加烧结助剂制得的样品在10 MHz下,相对介电常数εr为6.38,介电损耗tanδ为0.001 8.加复合烧结助剂P2O5和ZnO有效地降低了CBS玻璃粉末的烧结温度(低于900 ℃),可实现银、铜电极共烧.烧结助剂的作用机理是P2O5促进了液相的生成,ZnO则具有提高液相的粘度,增大烧结温度范围,细化晶粒和防止样品变形的作用.     

五氧化二磷对磷渣微晶玻璃烧结行为的影响

用烧结法制备了以磷渣为主要原料的徽晶玻璃,用正交实验、X射线衍射分析等研究了影响磷渣微晶玻璃烧结行为的因素.结果表明:影响磷渣微晶玻璃烧结因素的主次顺序为烧成温度、五氧化二磷(P2O5)含量、玻璃颗粒尺寸和烧成时间.在烧成温度、玻璃颗粒尺寸和烧成时间不变的情况下,P2O5含量对玻璃的烧结行为有显著的影响.当玻璃中P2O5的含量(质量分数,下同)小于1.8%,烧成温度低于1000℃时,微晶玻璃的主晶相β-CaSiO3,此时微晶玻璃表面凹凸不平.当玻璃中P2O5的含量大于3.6%,烧成温度高于1100℃,烧成时间显著增加,微晶玻璃的主晶相为Na2Ca2Si3O9,微晶玻璃表面粗糙不平.P2O5的最佳含量为1.8%～3.6%,最佳烧成温度为1000～1050℃,最佳烧成时间为60min时,可得到表面光滑平整的微晶玻璃.     

二次烧成对CaO-B_2O_3-SiO_2系微晶玻璃结构和性能的影响

研究一次和二次烧成对CaO-B2O3-SiO2(CBS)微晶玻璃的烧结性能与介电性能的影响。用X线衍射(XRD)、扫描电镜(SEM)等分析探讨二次烧成对CBS微晶玻璃的微观结构与介电性能的关系。结果表明:与一次烧成相比,二次烧成能够促进玻璃体中的小晶粒生长,试样的收缩率和体积密度有所增加,有利于介电常数提高和介质损耗的降低,且体系中没有出现新的晶相;875℃烧结的试样,X/Y轴收缩率均为14.33%,体积密度达到2.46 g/cm3,10MHz介电常数和损耗相应为6.21和3.5×10-3,热膨胀系数为11.86×10-6/℃,抗折强度为157.36MPa。     

CaO- ZnO-B2O3-SiO2玻璃/Al2O3低温共烧复合陶瓷基板研究

用CaO-ZnO-B2O3-SiO2玻璃和氧化铝陶瓷复合材料制备了低温共烧陶瓷基板.在CaO-B2O3-SiO2微晶玻璃中引入ZnO,玻璃微晶化后的主晶相仍为硅灰石,但它的软化温度有不同程度的降低,同时析晶温度也有了显著的改变.特别是以ZnO部分取代CaO时,析晶温度明显提高.该玻璃与氧化铝复合可以在较宽的温度范围内烧结.在850℃/30 min烧结,得到了气孔率为1%、介电常数εr = 7.10的陶瓷基板材料.     

BaO-Al2O3-B2O3-SiO2系微晶玻璃低温共烧陶瓷研究

采用烧结法制备了BaO-Al2O3-B2O3-SiO2系微晶玻璃低温共烧陶瓷。通过差热分析仪、影像式烧结点试验仪、X射线衍射仪等方法研究了玻璃组成以及烧结制度对微晶玻璃结构和性能的影响。结果表明:随着B2O3替代Al2O3量的增加,玻璃转变温度和烧结温度逐渐降低,析晶能力增强,有利于重硅酸钡晶体的析出,但不利于钡长石晶体的析出。烧结制度对析出晶体的种类和数量有很大影响。在850℃烧结2 h,微晶玻璃低温共烧陶瓷的气孔率低于1%,热膨胀系数在(7.05～12.78)×10-6/℃之间变化。     

珍珠岩制备单一α-堇青石微晶玻璃及其性能

以珍珠岩为主要原料制备了单相α-堇青石微晶玻璃.采用DSC、XRD及FESEM分别研究了微晶玻璃的烧结和晶化行为、晶相组成及显微结构.探讨了烧结温度和SiO2含量对微晶玻璃晶相、显微结构及性能的影响.结果表明,随着烧结温度升高,微晶玻璃中μ-堇青石逐渐减少并转变成α-堇青石,微晶玻璃的孔隙率减少.随着SiO2含量升高,α-堇青石晶相析出温度先降低后增高,微晶玻璃的密度及抗折强度先增大后减小,介电性能变差.当Mg∶Al∶Si=2∶2∶5.95时经900 ℃烧结6 h制得单一α-堇青石微晶玻璃,并具有高抗折强度(116 MPa),低介电常数(5.72,10 MHz),低介电损耗(0.0059,10 MHz),与Si相匹配的热膨胀系数(2.91×10-6 K-1),可以用作低温共烧陶瓷材料.     

Ca-B-Si掺杂对Ba（Zn1／3Ta2／3）O3陶瓷介电性能的影响

采用固相烧结法制备了添加烧结助剂Ca–B–Si（CBS）微晶玻璃的Ba（Zn1/3Ta2/3）O3（BZT）陶瓷。研究了CBS添加量对BZT陶瓷烧结温度和微波介电性能的影响。结果表明,CBS起到助溶剂的作用,添加CBS降低了BZT陶瓷的烧结温度,并改善了微波介电性能。添加2%（质量分数）的CBS时,BZT的烧结温度从纯...     

低温烧结CaO-B2O3-SiO2玻璃陶瓷及其性能

在CaO-B2O3-SiO2玻璃粉末中,通过添加助烧剂制备了CaO-B2O3-SiO2(CBS)玻璃陶瓷材料.研究了助烧剂P2O5和ZnO的助烧作用、材料的介电性能和相组成、显微结构.分析认为,P2O5能促进低熔点玻璃相的形成,ZnO则可以提高玻璃相的粘度,扩大烧结温度范围,并防止试样变形,复合添加P2O5和ZnO可成功烧结CBS玻璃粉末;在CBS玻璃陶瓷材料中,包含有β-CaSiO3、α-SiO2和CaB2O4三种晶相,晶粒发育均匀,粒径分布较合理,大小为0.5μm左右;添加质量分数为2%的P2O5和0.5%的ZnO作烧结助剂,可制备10MHz下,εr为6.38,tanδ小于0.002的玻璃陶瓷材料;烧结温度低于900℃,可实现银、铜电极共烧,可用作LTCC材料.     

Al_2O_3添加量对CBS/Al_2O_3复相陶瓷结构与性能的影响

采用流延法制备CBS/Al2O3复相陶瓷。运用FTIR、XRD、SEM和EDS等分析测试手段研究了Al2O3添加量对CBS/Al2O3复相陶瓷微观结构和介电性能的影响。结果表明:随着α-Al2O3添加量的增加,钙长石相的形成抑制了石英相和硅灰石相的生长,试样的烧结温度和致密度明显提高,烧结温度范围扩大。但Al2O3添加量大于48%时,玻璃液相不足以充分润湿陶瓷相,导致体系致密度下降。Al2O3添加量为48%的复相陶瓷850℃烧结,密度ρ=3.11 g·cm-3,10 MHz频率下,介电常数εr=7.95,介电损耗tanδ=1.1×10-3,能够与金浆低温共烧。     

硼硅酸盐玻璃鳞片研制开发概况

叙述了我国玻璃鳞片的研究和开发历程，提出了厚度和表面处理的重要性。     

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。     

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。     

Thermochemical Modeling of Oxide Glasses

A modified associate species approach is used to model the liquid phase in oxide systems. The relatively simple technique treats oxide liquids as solutions of end-member and associate species. The model is extended to representing glasses by treating them as undercooled liquids. Equilibrium calculations using the model allow the determination of species activities, phase separation, precipitation of crystalline phases, and volatilization. In support of nuclear waste glass development, a model of the Na₂O–Al₂O₃–B₂O₃–SiO₂ system has been developed that accurately reproduces its phase equilibria. The technique has been applied to the CaO–SiO₂ system, which is used to demonstrate how two immiscible liquids can be treated.     

The influence of iodide on glass transition temperature of high-pressure nuclear waste glasses

The glass transition temperature (T_g) is a key parameter to investigate for application in nuclear waste immobilization in borosilicate glasses. T_g for several glasses containing iodine (I) has been measured in order to determine the I effect on T_g. Two series of glass composition (ISG and NH) containing up to 2.5 mol% I and synthesized under high pressure (0.5 to 1.5 GPa) have been investigated using differential scanning calorimetry (DSC). The I local environment in glasses has been determined using X-ray photoelectron spectroscopy and revealed that I is dissolved under its iodide form (I⁻). Results show that T_g is decreased with the I addition in the glass in agreement with previous results. We also observed that this T_g decrease is a strong function of glass composition. For NH, 2.5 mol% I induces a decrease of 24°C in T_g, whereas for ISG, 1.2 mol% decreases the T_g by 64°C. We interpret this difference as the result of the I dissolution mechanism and its effect on the polymerization of the boron network. The I dissolution in ISG is accompanied by a depolymerization of the boron network, whereas it is the opposite in NH. Although ISG corresponds to a standardized glass, for the particular case of I immobilization it appears less adequate than NH considering that the decrease in T_g for NH is small in comparison to ISG.     

Corrosion of Borosilicate Glasses Subjected to Aggressive Test Conditions: Structural Investigations

Sodium borosilicate (NBS) and barium sodium borosilicate (BBS) glasses, used for immobilization of high‐level nuclear waste with compositions (SiO₂)_0.477(B₂O₃)_0.239(Na₂O)_0.170(TiO₂)_0.023(CaO)_0.068(Al₂O₃)_0.023 and (SiO₂)_0.482(B₂O₃)_0.244(Na₂O)_0.220(BaO)_0.054 were subjected leaching experiments under hydrothermal conditions in an autoclave at 200°C for different time durations. Morphological and structural transformations associated with leaching, have been monitored with techniques like XRD, SEM, solid‐state nuclear magnetic resonance. XRD and SEM along with NMR studies have confirmed that, upon leaching, formation of an aluminosilicate phase, Zeolite‐P (Na₆Al₆Si₁₀O₃₂·12H₂O), occurs with NBS glass. BBS glass upon subjecting to the same conditions leads to formation of multiple amorphous phases having Q⁴ (silica rich phase) and Q³ structural units of Silicon along with structurally modified residual glass. Upon leaching BO₃ structural units preferentially get released from BBS glass. Comparison of results with international simple glass confirmed that, for the latter, mass loss rates are one order of magnitude lower.     

酸浸析对多孔玻璃性能的影响

以Na2O·B2O3·SiO2为玻璃制备系统,采用原子力显微镜、扫描电镜和氮气吸附仪分析了酸处理工艺制度对多孔玻璃孔容、平均孔径和孔径分布的影响,经过热处理和酸腐蚀后多孔玻璃的孔容可达0.8845cm3·g-1、平均孔径达76.55nm;相同H+离子浓度的盐酸和硫酸酸处理得到的多孔玻璃,其比表面积、孔容和平均孔径相差不大;用浓度为0.1mol·L-1的硫酸处理后多孔玻璃的平均孔径比浓度为1mol·L-1的略大,并对酸处理参数对多孔玻璃性质的影响进行了分析和讨论,为制备较大孔径的多孔玻璃介质奠定了基础.     

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.     

Dissolution of silica component of glass network at early stage of corrosion in initially silica-saturated solution

Corrosion of glass in silica-saturated solution has been performed with the assumption that dissolution of silicate species from the glass network would not occur. Using surface-sensitive analytical techniques, we report experimental evidence suggesting the dissolution of silicate network species from a model nuclear waste glass, called international simple glass (ISG), in an aqueous solution initially saturated with soluble silica species. Results from low energy ion scattering and X-ray photoelectron spectroscopy reveal a complete depletion of mobile element species (B, Na) from the ISG surface and an enrichment of Zr on the outmost surface. In support of spectroscopic analyses, results from topographic imaging with atomic force microscopy show a stochastic dissolution of glass surface resulting in a higher surface roughness with increasing corrosion time in aqueous solution. This study shows that a true equilibrium between soluble silica species in the solution phase and silicate species in the glass network could not be warranted by performing corrosion experiments in the solution where dissolved silica species are initially equilibrated with amorphous silica in the presence of KOH. The leaching of mobile species (B, Na) could affect the saturation level of aqueous solution and induce further dissolution of the glass surface.     

Investigations into the thermal stability of sol-gel-derived glasses as models for thermally grown oxides

The thermal stability of sol-gel-derived silica and borosilicate glasses exposed to dry O₂ at 800 and 1200°C for 100 hours was characterized by weight change, thermal transitions, morphology, structure, and composition to investigate suitability as models for thermally grown oxides. Rapid weight loss was observed in the first few hours of isothermal exposure for borosilicate glasses, followed by constant weight loss at a low rate for the balance of the exposure. Weight loss resulted from loss of residual hydroxyl species retained from the sol-gel synthesis, and from oxidation of carbon retained from thermal decomposition of the organic precursors by pyrolysis. Characterization of the sol-gel-derived glasses showed structural similarities to silica and binary borosilicate glasses synthesized by melt or vapor deposition methods, and to thermally grown oxides. Oxygen transport mechanisms through the sol-gel-derived glasses is not thought to be affected by the retained carbon. However, a silica-enriched glass surface resulting from boria volatility, observed from a borosilicate glass exposed dry O₂ at 1200°C, will slow O₂ transport rates. The results show that sol-gel-derived silica and borosilicate glasses can be used as models for thermally grown oxides.