核化温度对钢渣玻璃陶瓷性能的影响

以钢渣为主要原料制备玻璃陶瓷。测定了在不同核化温度下试样的抗弯强度,用DTA、XRD和SEM研究核化温度范围并鉴定玻璃陶瓷主晶相。探讨了核化温度与抗弯强度之间的关系。研究表明:抗弯强度、晶相含量随温度的升高先提高然后有所下降。用钢渣生产玻璃陶瓷是钢渣开发利用的一条有效新途径。     

含复合晶核剂CaO-MgO-A12O3-SiO2微晶玻璃析晶与性能

采用高温熔制法制备了含复合晶核剂的CaO-MgO-A12O3-SiO2(CMAS)微晶玻璃,并借助差热分析、X射线衍射、扫描电子显微镜分析了复合晶核剂组成对CMAS微晶玻璃的析晶和性能的影响规律.结果表明:复合晶核剂CaF2+TiO2能使CMAS玻璃的析晶活化能E降至329.2 kJ/mol,且促进晶体快速生长;CaF2+P2O5可促进大量晶核生成,使晶体生长指数n增至2.87,从而实现CMAS玻璃整体析晶;CMAS微晶玻璃的主晶相为钙长石和透辉石,形状为长条状,TiO2和ZrO2的加入对主晶相种类和形状没有影响,但P2O5加入后玻璃不能析出透辉石晶相,而是辉石晶相,并产生许多细小晶粒;含复合晶核剂的微晶玻璃均具有较高Vicker硬度(7.0 GPa以上),但引入CaF2+TiO2+P2O5时,微晶玻璃的Vicker硬度较低,这主要是晶粒排列不致密所致.     

Dispersant-free colloidal fabrication of Bi2Sr2CaCu2O8 superconducting thick films

Bi₂Sr₂CaCu₂O_x thick films have been fabricated using colloidal processing. The composition of the suspension has been optimised using sedimentation experiments and rheological measurements. It has been stated that well-dispersed suspensions of Bi₂Sr₂CaCu₂O_x can be obtained when ethanol is used as a solvent without the addition of deflocculants. Using the fits of the viscosity curves to the Krieger–Dougherty model, it has been possible to determine that the maximum volume fraction of solids leading to stable suspensions is 0.37. With these suspensions, it has been possible to fabricate films with 130 μm in thickness that show enough resistance to cracking and allow easy handling. Superconducting coatings have been obtained without dispersant.     

Mechanical Properties of Textured Bi2Sr2CaCu2O8+delta High-Temperature Superconductors

The mechanical properties of Bi₂Sr₂CaCu₂O_8+delta fibers produced via laser-induced directional solidification at different growth rates were determined through longitudinal and transverse tension tests, as well as flexure tests. In addition, polished sections of as-received fibers and the fracture surfaces of the broken samples were examined using scanning electron microscopy to elucidate the relationship between the microstructure and the mechanical properties. The fibers were anisotropic, and the transverse fiber strength was very low, because of early failure via cleavage of the grains perpendicular to the c -axis. The longitudinal strength and the degree of anisotropy increased as the fiber growth rate decreased, whereas the transverse strength followed the opposite trend. This behavior was due to changes in the porosity and the alignment of the crystals along the fiber axis.     

Transparent Hafnia-Containing β-Quartz Glass Ceramics: Nucleation and Crystallization Behavior

Heterogeneous nucleation and crystallization of lithium alumosilicate glasses with hafnia-containing nucleation agents was explored. Kinetic, thermodynamic, and structural data were considered to assess nucleation efficiency and to characterize the crystallization process. It is shown how lattice parameters and, particularly, anisotropy of the nuclei phase depend on the amount of ZrO₂–HfO₂ substitution in a specific base glass. For a given crystallization treatment, the size of the derived crystallites of β-quartz structure is used as a measure of nucleation rates. A nonlinear dependence of nucleation efficiency on HfO₂ content was established, with the supposedly most efficient nucleation corresponding to the lowest degree of anisotropy of the nuclei crystallites, i.e., when about 20%–30% of ZrO₂ was substituted by HfO₂. Apparent activation energies and estimates of the Avrami coefficient were determined from nonisothermal crystallization experiments for selected compositions to highlight the differences between hafnia and zirconia. Hafnia can be used alone or in combination with other agents to nucleate nanocrystalline glass ceramics with a low coefficient of thermal expansion.     

Bi掺杂Ba0.6Sr0.4TiO3陶瓷的研究

本文采用传统的陶瓷工艺合成了Ba0.6Sr0.4TiO3陶瓷,研究了Bi掺杂对材料参数ε、tanδ和E的影响,并探讨了相关的掺杂改性机理。结果表明：适量的Bi能够改善陶瓷的介电性能,同时细化陶瓷的晶粒尺寸。     

含Bi2O3的MgO-Al2O3-SiO2玻璃核化与晶化动力学研究

使用差热分析(DTA)的方法研究了含Bi2O3的MgO-Al2O3-SiO2玻璃粉末(粒度≤0．054mm)的核化与晶化动力学。由此方法确定了样品最大成核速度温度，同时计算出晶体生长的活化能和动力学参数。结果表明，含Bi2O3玻璃的晶化指数(n)和晶体生长维数(m)都为1．15(约等于1)，这说明该玻璃的晶化机制是表面晶化。由Kissinger和Augis—Bennett方程计算出的活化能较为接近，平均值为401kJ／mol。     

Preparation of Bi2Sr2CaCu2Ox Thin Film by Pulsed Laser Deposition for Optoelectronic Devices Application

Silicon - We report on the fabrication of Bi2Sr2CaCu2Ox (BSCCO) nanostructure films by pulsed laser deposition technique (PLD). The structural and optical properties of nanostructured Bi2Sr2CaCu2Ox...     

The Effect of Barium Substitution on the Ferroelectric Properties of Sr2Nb2O7 Ceramics

This work revealed that the solid solution compounds of Sr_{2 ? x}Ba_xNb₂O₇ are promising lead‐free materials for high‐temperature piezoelectric sensor application. These compounds were confirmed as ferroelectric materials with high Curie points ( > 900°C) by their piezoelectric activity after poling, ferroelectric domain switching in their P–E hysteresis loops and thermal depoling behavior. The effect of Ba substitution on the structure and properties of Sr_{2 ? x}Ba_xNb₂O₇ (x  <  1.0) was investigated. The solid solution limit of Sr_{2 ? x}Ba_xNb₂O₇ was determined by XRD as x < 0.6. The a‐, b‐, c‐ axes, and cell volume increase with Ba addition. The textured ceramics of Sr_{2 ? x}Ba_xNb₂O₇ were prepared for the first time. The highest d₃₃ was measured as 3.6  ±  0.1 pC/N for Sr_1.8Ba_0.2Nb₂O₇.     

转炉渣微晶玻璃热处理制度研究

本文以60%转炉渣和40%硅石为原料,采用熔融法制备了微晶玻璃.借助XRD,SEM和DTA等分析手段研究了晶化和核化时间对微晶玻璃析晶行为和性能的影响.在不同的晶化和核化时间下,微晶玻璃的晶相均为钙铁辉石和铁透辉石,晶体均为球形.随着晶化时间的延长,晶体析出量增加,微晶玻璃的平均粒径和显微硬度均呈先增大后减小的趋势,当晶化时间为75 min时达到最大值,分别为0.44 μm和733 Hv;随着核化时间的延长,晶体尺寸逐渐减小,晶核数量逐渐增加,显微硬度变化平缓.     

添加物对氧化锌基陶瓷性能的影响

变阻器在电工中得到广泛的应用，它主要是用陶瓷材料制成的，在其中加入各种添加物，会改善其烧结特性，进而可生产出结构均匀的陶瓷制品。     

Silver Co‐Firable Li2ZnTi3O8 Microwave Dielectric Ceramics with LZB Glass Additive and TiO2 Dopant

New dielectric ceramics are prepared by the conventional solid‐state ceramic route. Effects of LZB glass on sintering, phase purity, microstructure, and dielectric properties of Li₂ZnTi₃O₈ ceramics have been investigated. Adding LZB lowers sintering temperature from 1050°C to 875°C, and does not induce much degradation of dielectric properties. The 1.0 wt% LZB glass‐added ceramic has better properties of ε_r = 23.9, Q × f = 31,608 GHz, τ_f = ?14.3 ppm/°C. Additions of TiO₂ markedly improve microwave properties. Typically, the Li₂ZnTi₃O₈ + 1 wt%LZB + 3.5 wt%TiO₂ sintered at 900°C shows ε_r = 26.1, Q × f = 45,168 GHz, τ_f = ?4.1 ppm/°C. Compatibility with Ag electrode indicates that this material may be applied to LTCC devices.     

增加TiO2,Nb2O5晶核剂对烧结微晶玻璃结构与性能的影响

在Ｌｉ２Ｏ－ＭｇＯ－Ａｌ２Ｏ３－ＳｉＯ２系玻璃中，加入不同含量的ＴｉＯ２或Ｎｂ２Ｏ５为晶核剂，经过粉碎，混和，成型，烧结能制得致密的微晶玻璃，微晶玻璃的强度比示添加ＴｉＯ２或Ｎｂ２Ｏ５的样品有所提高，当ＴｉＯ２，Ｎｂ２Ｏ５含量增加，微晶玻璃强度也相应增加，加入ＴｉＯ２或Ｎｂ２Ｏ５添加物对微晶玻璃的热膨胀系数影响较小，电子显微归咎表明，晶体颗粒随着添加物ＴｉＯ２或Ｎｂ２Ｏ５的增加而减小，Ｘ光衍射结果     

添加氟化物对硅灰石玻璃陶瓷性能的影响

以钙铝黄长石、废玻璃粉为主要原料,分别添加MgF2、BaF2及复合氟化物,用反应析晶烧结法制备硅灰石玻璃陶瓷.使用X射线衍射(XRD)、扫描电子显微镜(SEM)对样品的物相和形貌进行表征.对添加不同氟化物制备的硅灰石玻璃陶瓷进行了密度、收缩率、气孔率、吸水率、抗弯强度、抗压强度等性能测试.结果表明,添加MgF2、BaF2或复合氟化物制备的玻璃陶瓷主晶相均为硅灰石.添加MgF2可促使硅灰石玻璃陶瓷大量析晶,密度较低,吸水率和气孔率均较高,抗压强度大大降低.添加BaF2或复合氟化物具有较低的吸水率和气孔率,较高的密度,以及较高的抗弯强度和抗压强度.添加复合氟化物后可通过玻璃陶瓷的自收缩作用实现其烧结致密化,当添加5％MgF2与5％BaF2后,制得的硅灰石玻璃陶瓷体积密度2.4322 g/cm3,相对密度90.93％,气孔率0.27％,吸水率0.06％,抗弯强度54 MPa,抗压强度239 MPa.     

Enhanced Thermoelectric Properties of Bi2O2Se Ceramics by Bi Deficiencies

Polycrystalline Bi_2?xO₂Se ceramics were synthesized by spark plasma sintering process. Their thermoelectric properties were evaluated from 300 to 773 K. All the samples are layered structure with a tetragonal phase. The introduction of Bi deficiencies will cause the orientation alignment and change of effective mass. As a result, a significant enhancement of thermoelectric performance was achieved. The maximum of Seebeck coefficient is ?568.8 μV/K for Bi_1.9O₂Se at 773 K, much larger than ?445.6 μV/K for pristine Bi₂O₂Se. Featured with very low thermal conductivity [~0.6 W·(m·K)^?1] and an optimized electrical conductivity, ZT at 773 K is significantly increased from 0.05 for pristine Bi₂O₂Se to 0.12 for Bi_1.9O₂Se by introducing Bi deficiencies, which makes it a promising candidate for medium temperature thermoelectric applications.     

粉体烧结法制备堇青石基微晶玻璃的研究

以MgO-Al2O3-SiO2系玻璃为研究对象,用铅硅玻璃作为烧结助剂,采用粉体烧结法制备堇青石基微晶玻璃,研究了烧结微晶玻璃的形成过程,铅硅玻璃在烧结中的作用及对烧结样品密度的影响,结果表明：铅硅玻璃的加入,促进了微晶玻璃的烧结致密化,烧结样品的密度随着铅硅玻璃加入量的增加而变大。     

Slurry‐Based Additive Manufacturing of Ceramics

Most additive manufacturing (AM) techniques have in common that material is spread out as thin layers of a dried powder/granulate by a roller or a shaker system. These layers are mostly characterized by a low packing rate. On the other hand, appreciable densities can be reached by the use of ceramic slurries. In this context, the layer‐wise slurry deposition (LSD) has been developed. Specific features of the LSD process are reflected on the basis of already existing additive manufacturing technologies. The microstructure of laser‐sintered bodies will be discussed, and strategies for an improved microstructure during sintering will be introduced.     

Effect of Na-doping on thermoelectric and magnetic performances of textured Bi2Sr2Co2Oy ceramics

Bi₂Sr_2-xNa_xCo₂O_x (x = 0.0, 0.025, 0.050, 0.075, 0.100, and 0.125) samples were prepared through the solid-state route and textured using the laser floating zone technique. Microstructural analysis of as-grown samples showed well oriented grains and a relatively high amount of secondary phases due to their incongruent melting. Annealing procedure has drastically decreased the number and amount of secondary phases. Moreover, Na-doping has further decreased the secondary phases content and improved grain alignment. These modifications have been reflected in a large decrease of electrical resistivity with the annealing procedure. The maximum power factor values have been obtained in 0.075 Na-doped annealed samples, 0.20 mW/K²m, which are much higher than the best values obtained in textured materials through hot uniaxial pressing. Magnetic properties were very similar for all samples, with paramagnetic Curie temperature and effective magnetic moment values of ?48.6 K and ≈2 μ_B, respectively.     

Bi2O3对钠钙硅玻璃熔体性质的影响研究

浮法玻璃的熔化是在非常高的温度下进行的,且熔化和澄清占总能耗的60%左右。本文以降低浮法玻璃熔化温度为出发点,研究氧化铋的引入对浮法玻璃熔体性质、熔化温度、玻璃结构的影响。研究表明:在浮法玻璃组成中引入氧化铋,加入0.5%～2%的氧化铋后,未改变玻璃的基本结构。加入Bi₂O₃后玻璃熔体的粘度明显降低,在玻璃熔体粘度为Lgη=1.35 Pa·s时,A₅玻璃试样的对应温度与A₁相比,降低约30℃。     

Effect of Glass Addition on the Microwave Dielectric Properties of CaMgSi2O6 Ceramics

CaMgSi₂O₆ (CMS) ceramics prepared by the solid-state ceramic route have a sintering temperature of 1300°C/2 h. The sintering temperature of CMS was reduced below the melting point of Ag using low-melting LBS and LMZBS glasses. In the case of CMS+15 wt% LMZBS sintered at 900°C/2 h, the dielectric properties obtained were ɛ_r=8.2, Q_u×f=32,000 GHz (10.15 GHz), and τ_f=–48 ppm/°C. The CMS+15 wt% LBS composite, sintered at 925°C/2 h, showed ɛ_r=8, Q_u×f=15,000 GHz (10.17 GHz), and τ_f=–49 ppm/°C. The chemical compatibility of Ag with the ceramic–glass composites was also investigated for low-temperature co-fired ceramic applications.