热处理制度对Li20-Al2O3-SiO2系微晶玻璃晶化过程和性能的影响

采用熔融法获得了以 TiO2+ZrO2 和 P2O5 为复合晶核剂的 LiO-Al2 O3-SiO2 系统基础玻璃,通过差热分析和正交实验的方法确定了使该玻璃微晶化的热处理制度,获得了不同热处理制度下 Li2O-Al2O3-SiO2 系统低膨胀微晶玻璃.利用 X 射线衍射分析和扫描电子显微镜对晶化样品的物相和微观结构进行了研究;讨论了热处理制度对玻璃的晶化过程及热膨胀系数的影响.研究结果表明:不同热处理温度下的微晶玻璃均可以得到具有细小等轴晶粒的组织结构,材料的热膨胀系数较低;析晶初始温度下首先析出的晶相为β-石英固溶体,随晶化温度升高β-石英固溶体转变为β-锂辉石固溶体,晶化温度进一步升高,β-锂辉石固溶体结晶完全,材料的热膨胀系数更低.     

阳极键合用Li2O-Al2O3-SiO2微晶玻璃电学性能

采用合适的组分和二步热处理法制备了热膨胀系数与硅片匹配的Li2O-Al2O2-SiO2(LAS)微晶玻璃,并在满足键合所要求的热膨胀系数的基础上,通过调节成分和控制热处理制度,研究了微晶玻璃的导电和介电性能.结果表明:采用不同的热处理制度进行晶化处理,LAS微晶玻璃的主晶相均为β-锂辉石;607℃核化、980℃晶化时间均为3 h样品的热膨胀系数为31.16 ×10℃-1(200～400℃),与硅片热膨胀系数较接近;微晶玻璃的电阻率大于基础玻璃,且随温度的升高电阻率吴下降趋势;改变核化和晶化时间,在150～360℃范围内其电阻率变化不大;微晶玻璃的介电常数和介电损耗均小于基础玻璃,更适宜作为电子器件的绝缘封装材料.     

热处理制度对Li2O-A12O3-SiO2系微晶玻璃晶化过程和性能的影响

采用熔融法获得了以TiO2＋ZrO2和P2O5为复合晶核剂的Li2O-Al2O3-SiO2系统基础玻璃,通过差热分析和正交实验的方法确定了使该玻璃微晶化的热处理制度,获得了不同热处理制度下Li2O-Al2O3-SiO2系统低膨胀微晶玻璃。利用X射线衍射分析和扫描电子显微镜对晶化样品的物相和微观结构进行了研究;讨论了热处理制度对玻璃的晶化过程及热膨胀系数的影响。研究结果表明：不同热处理温度下的微晶玻璃均可以得到具有细小等轴晶粒的组织结构,材料的热膨胀系数较低;析晶初始温度下首先析出的晶相为β-石英固溶体,随晶化温度升高β-石英固溶体转变为β-锂辉石固溶体,晶化温度进一步升高,β-锂辉石固溶体结晶完全,材料的热膨胀系数更低。     

超低膨胀微晶玻璃热处理工艺优化研究

采用熔融法制备了Li₂O-Al₂O₃-SiO₂系透明玻璃,以TiO₂、ZrO₂和P₂O₅为复合晶核剂对该玻璃进行热处理,获得了超低膨胀微晶玻璃。采用正交试验研究了热处理工艺参数对微晶玻璃热膨胀系数的影响,并通过计算分析获得了最优的热处理工艺参数,即核化温度为600 ℃,核化时间为3 h,晶化温度为820 ℃,晶化时间为5 h。在此热处理工艺制度下获得的微晶玻璃主晶相为β-石英固溶体,热膨胀系数为1.6×10^-8 ℃^-1。采用差热分析、X射线衍射分析、扫描电子显微镜分析、透射电子显微镜分析等手段研究了微晶玻璃的析晶情况和微观结构,并进一步分析了热处理工艺与微晶玻璃热膨胀性能和微观结构之间的对应关系。结果表明,微晶玻璃的热膨胀系数由晶相种类和含量决定,微晶玻璃内部晶相的尺寸和含量与热处理工艺密切相关。     

利用正交法优化掺杂La2O3微晶玻璃的热处理制度

实验在前期研究工作基础上选择了稀土氧化物La2O3,采取外加法对Li2O-Al2O3-SiO2(LAS)系统微晶玻璃进行掺杂,为了寻找掺杂La2O3后LAS系统微晶玻璃的最佳热处理制度,采用正交试验设计,对试样在不同温度下进行了热处理,并对晶化后各试样进行了各项性能测试并对测试结果进行了分析,结果表明:热处理制度对微晶玻璃的各项性能影响显著,其中又以晶化温度的影响最大;综合各项性能后,得到合适热处理制度为590℃/1 h→790℃/2 h,此时,试样的力学性能和热膨胀性能最好,其抗折强度为141 MPa,热膨胀系数为1.26×10-7℃-1(20～400℃).     

TiO_2和热处理温度对高镁钢渣微晶玻璃性能的影响

借助DTA,XRD和SEM等测试手段,研究了TiO_2和热处理温度对高镁钢渣微晶玻璃性能的影响。实验结果表明,随着TiO_2质量分数增加,微晶玻璃的玻璃化温度和析晶温度降低,抗弯强度和维氏硬度提高,热膨胀系数下降;随着热处理温度的提高,微晶玻璃的热膨胀系数下降,抗弯强度和维氏硬度在1 100℃达到最高。同时整个样品结构由玻璃相为连续相过渡为晶体为连续性相,主晶相是MgSiO_3。     

MgO-Al2O3-SiO2系统微晶玻璃的析晶及热处理工艺研究

用XRD、DTA对MgO-Al2O3-SiO2系微晶玻璃材料的析晶过程进行了研究,讨论了热处理温度及时间对微晶玻璃热膨胀系数的影响,表明了各种晶体的析出特点.     

La2O3的添加对P2O5-Al2O3-SiO2系微晶玻璃性能的影响

以ZrO2为晶核剂,根据DSC图谱制定合理的热处理制度,制备了磷扩散源P2O5-Al2O3-SiO2系微晶玻璃。采用XRD分析观察了P2O5-Al2O3-SiO2系微晶玻璃的析晶状况,热膨胀仪测试了该微晶玻璃的膨胀系数,分析La2O3的含量对P2O5-Al2O3-SiO2系微晶玻璃在高温下释放P2O5速率的影响。结果表明:随着La2O3含量增加,P2O5-Al2O3-SiO2系微晶玻璃中晶体含量增加,主晶相未发生改变,都为磷酸锆晶体;同时,该微晶玻璃的热膨胀系数相对降低,P2O5的释放速率也随之增加。     

复合晶核剂TiO2/ZrO2对MgO-Al2O3-SiO2系统微晶玻璃的影响研究

本文制备了Mg0-Al2O3-SiO2系微晶玻璃,用XRD、DTA等方法对该系统微晶玻璃材料进行了研究;讨论了复合晶核剂对材料热膨胀性能及热处理温度的影响.结果表明TiO2/ZrO2复合晶核剂中,少量ZrO2(＜0.5wt%)能够降低微晶玻璃材料的热处理温度和热膨胀系数.     

玻璃组成对Li2O-Al2O3-SiO2系统微晶玻璃膨胀系数的影响

以Li2O-Al2O3-SiO2系统微晶玻璃的标准样的组成为基础配方,改变玻璃组成中各种氧化物的含量,采用传统的熔融法制备了Li2O-Al2O3-SiO2系统微晶玻璃,利用SEM、XRD、DTA及热膨胀系数测定等分析手段,重点研究了玻璃组成中Li2O、Al2O3、SiO2的含量对微晶玻璃热膨胀系数的影响.研究结果表明:在标准试样的基础上,改变Li2O的含量,对热膨胀系数影响很大;热膨胀系数随Al2O3含量增大而增大,而SiO2含量的变化,对热膨胀系数影响不大.     

Preparation and Properties of Glass-Ceramics Derived from Nitrogen-Containing β-Spodumene Glasses

Crystallization of Li-Al-Si-O-N oxynitride glasses based on the β-spodumene composition and the properties of the resultant glass-ceramics have been studied. The onset of the precipitation of metastable high-quartz solid solution and its transformation to β-spodumene shift to higher temperatures with increasing nitrogen content of the oxynitride glasses. Nitrided glass-ceramics crystallized at 1200°C have negative thermal expansion coefficients, since high-quartz structure is maintained up to 1000° and 1200°C. Knoop hardness and density of the glass-ceramics increase with increasing nitrogen content. There was evidence that part of the nitrogen atoms were incorporated into the high-quartz solid-solution structure and that a small amount of the minor phase of Si₂N₂O was precipitated in highly nitrided glass-ceramics.     

Glass-ceramics from a zinc-electroplating solid waste: Devitrification promoted further crystallization of parent glass upon heat treatment

A solid waste from a zinc electroplating production line was successfully used as a main raw material for synthesizing glass-ceramics with a fine microstructure. X-ray fluorescence spectroscopy analysis on dried solid waste shows that the waste mainly contains iron and zinc oxides. X-ray diffraction (XRD) analysis identifies Fe₃O₄ and ZnO phases in calcined waste samples. Based on the above results, silica sand, lime stone and potassium feldspar were proportionally added to make parent glasses by melting the batches at 1450?°C for 2?h. The as-synthesized products show typical DSC and thermal expansion curves with obvious glass transition phenomenon. However, XRD patterns reveal that they had devitrified to form ZnFe₂O₄ phase during the shaping and cooling of the melts. The devitrification became weaker when more potassium feldspar was added. It is interesting to find that the pre-crystallization of ZnFe₂O₄ in the devitrified sample was beneficial to its further crystallization during the following heat-treatment. The result implies that the devitrification of parent glasses is not necessarily a detriment to the preparation of glass-ceramics via controlled crystallization process.     

晶化时间对MgO-Al2O3-SiO2微晶玻璃相转变及热膨胀性能的影响

采用XRD、DTA、SEM等测试方法,对MgO-Al2O3-SiO2（MAS）系微晶玻璃的析晶和微观结构进行了研究,讨论了不同的晶化时间对MAS微晶玻璃析晶行为及其热膨胀性能的影响。结果表明：在1050℃保温,堇青石能快速地晶化析出。随着晶化时间的增长,堇青石相逐渐增多,当晶化2h时几乎完全析出,析出晶粒大小约为2～5um。MAS系微晶玻璃的热膨胀系数与相组成有着密切的关系,随着晶化时间的延长,热膨胀系数逐渐减小。     

高品质超低膨胀透明微晶玻璃实现批量化生产

锂铝硅系超低膨胀微晶玻璃是一种性能优良的低膨胀光学材料,热膨胀系数低、透明性好。国产高品质超低膨胀微晶玻璃一直受到技术制约,难以批量化生产。本研究采用熔融法结合搅拌工艺以及适宜的热处理制度,成功批量化生产出热膨胀系数接近于零的高品质超低膨胀透明微晶玻璃产品,产品外观完整,内部基本无气泡、条纹等缺陷。对优级产品进行热膨胀系数、应力双折射、抗弯强度测试,结果表明,优级产品热膨胀系数为1.6×10^-8 K^-1,应力双折射小于2 nm/cm,抗弯强度高达171 MPa,品质已达到ZERODUR零级。采用XRD、SEM、TEM等手段对该产品的物相组成、表面形貌、微观结构进行了分析研究,产品主晶相为β-石英固溶体,晶相含量较高且分布均匀,晶粒尺寸为几十纳米,保证了其极低的热膨胀系数和高透明性。     

Fe2O3对CaO-SiO2玻璃和微晶玻璃性能的影响

利用溶胶-凝胶法制得Fe2O3-CaO-SiO2系基础玻璃,研究不同含量的Fe2O3对CaO-SiO2玻璃和微晶玻璃性能的影响.经分析,不同组分的玻璃凝结时间不同,处于低共熔点的样品凝结时间最短,而离低共熔点最远的样品凝结时间最长.样品的密度并不随成分而变化.溶胶凝胶转变过程中,不同组分所得的凝胶玻璃有一定的耐酸碱性.而微晶玻璃的耐酸碱性比玻璃都略有增强.微晶玻璃的饱和磁化强度和磁铁矿在玻璃中所占的体积分数有关.随着玻璃中Fe2O3含量的增加,饱和磁化强度增大.     

Crystallization mechanisms of cordierite glass-ceramics with “surface-center” crystallization behavior

Cordierite glass-ceramics usually begin to crystallize from the surface. As an efficient nucleating agent, TiO₂ can promote the rapid transformation of glass to bulk crystallization, but it is easy to cause the increase of dielectric constant and light absorption. High crystallinity cordierite glass-ceramics were prepared by optimizing the heat treatment process without or with different nucleating agents in stoichiometric cordierite glasses. The results show that the crystallization mechanisms of glasses without and with ZrO₂+P₂O₅ as nucleation agents are controlled by surface crystallization. While, the glass with TiO₂+ZrO₂+P₂O₅ as nucleation agents have the tendency to be bulk crystallization. The studied glasses are crystallized from surface and have different crystallization orientations with the inner glass. The thickness of crystalline layer increased with the increasing of heating temperatures, but the “surface-center” crystallization process cannot complete by further increasing heating temperatures because of softening deformation of glasses. At 1020 ℃, the glasses complete the “surface-center” crystallization for long durations. The glasses without nucleation agents and with ZrO₂+P₂O₅ require 10 h, but the glass with TiO₂+ZrO₂+P₂O₅ complete for 5 h. Although all the three glasses complete the “surface-center” crystallization, the glasses with nucleation agents show the higher crystallinity upon the same heat treatments. Finally, glass-ceramics with excellent performance were obtained, for example, the Z1# glass-ceramic have the high microhardness ∼7.4 GPa, low thermal expansion coefficient ∼1.4☓10⁻⁶ ℃⁻¹ at 20–300 ℃, and relatively high thermal conductivity ∼2.4 W/mK. It also exhibits low dielectric constant and loss, which was ∼4.5 and ∼1.2☓10⁻³ at 1 MHz, ∼ 4.9 and 2.3☓10⁻³ at 10.5 GHz..     

Thermal Expansion Behavior of Boron-Doped Cordierite Glass-Ceramics

The linear thermal expansion coefficients of cordierite glass-ceramics that have been doped with a fixed amount of P₂O₅ and 1, 2, and 3 wt% of B₂O₃ show negative expansion in the temperature range of 100°-300°C. The expansion of the undoped cordierite sample is positive. A relative decrease in the degree of negative expansion is observed as the B₂O₃ concentration increases. These negative expansion coefficients are similar to those of cordierite glass-ceramics that have been doped with the potassium cation.     

Physical and structural properties of Ge-rich chalcogenide glass sandwiched by GeS crystalline layers

Ge-rich glass-ceramics sandwiched by GeS crystalline layers were fabricated through 10?h thermal treatments at different temperatures. Surface crystallization is evidenced by XRD investigation of glass-ceramic samples polished by different times. SEM observation shows that the thickness of the crystalline layer is about 100?µm for the sample thermally treated at 395?°C for 10?h. The physical properties, including transmission spectra, density, Vickers hardness, and thermal expansion coefficient, were characterized and discussed with the evolution of GeS crystalline layers. This work not only establishes the correlation between microstructure and physical properties of chalcogenide glass-ceramics sandwiched by GeS, but also provides important evidence of structural similarity for understanding the network structure of Ge-S chalcogenide glasses.