Crystal growth induced by Nd:YAG laser irradiation in patterning glass ceramic substrates with dots

In this work a glass ceramic substrate was processed by focusing a laser beam inside the said material. The crystal phase within the amorphous matrix provides mechanical properties to the glass ceramic substrate in such a way that dots can be patterned inside the fore-mentioned material without producing any cracks. These marks are made up of crystals, the growth of which has been induced by the laser beam. These inner structures can modify the optical, thermal and mechanical properties of the glass ceramic substrate.A Q-switched Nd:YAG laser at its fundamental wavelength of 1064 nm with pulsewidths in the nanosecond range has been used.Morphology, composition, microstructure, mechanical and thermal properties of the processed material are described.     

Li_2O－MgO－CaO－Al_2O_3－SiO_2系微晶玻璃烧结反应形成的

Ｌｉ＿２Ｏ－ＭｇＯ－ＣａＯ－Ａｌ＿２Ｏ＿３－ＳｉＯ＿２系微晶玻璃烧结反应形成的相关系和显微结构诸培南，郭景坤，杨涵美，张玉峰，黄士忠（同济大学２０００９２）（中国科学院上海硅酸盐研究所２０００５０）ＰｈａｓｅＲｅｌａｔｉｏｎａｎｄＭｉｃｒｏｓｔｒｕｃ...     

Cr2O3与玻璃复合的玻璃陶瓷及其应用

The glass-ceramic material compounded with Cr2O3 and SiO2-BaO system glass has improved heat resistance and strength properties. It can be used not only as high temperature enamel, but also as ceramic body for sealing with Gaybon-steel to form high pressyreresustance element, This paper diseribes two kinds of processes on thin laye enamel and thick layer sealing, and descusscs their technology propertics and combining mechanism.     

The effect of SiC addition on the crystallization kinetics of atmospheric plasma–sprayed basalt-based coatings

The crystallisation kinetics of the conversion of a glass coating layer made from a mixture of natural basalt volcanic rock and SiC into glass-ceramic have been investigated. The process depends on the crystallisation temperature, time and amount of the SiC added. Coating powders were prepared from pure basalt and from basalt containing 10–50 wt% SiC. The powders were coated by an atmospheric plasma spray technique on the pre-coated AISI 1040 steel substrate with Ni–Al. The coating layer was vitrified by sudden cooling. The amorphous structure of the coatings was verified by X-ray diffraction (XRD) analysis. To obtain glass-ceramic, coatings were subjected to crystallisation heat treatment in an argon atmosphere. Crystallisation heat treatment temperatures of 800 °C, 900 °C and 1000 °C were chosen by using DTA. After the heat treatment process, augite, ferrian-diopsite, diopside, albite, andesine, and moissonite phases formed in the coating layer and were verified by XRD analysis. The crystallisation activation energies were determined to be between 323.4 kJ/mol and 253.2 kJ/mol, depending on SiC addition. The crystallisation activation energies decreased with increasing amounts of SiC addition. The Avrami parameters of the crystallisation process varied between 1.60 and 3.33, which indicates that internal crystallisation dominated for all of the compositions.     

Highly efficient and thermally stable MnII-based phosphor-in-glass towards warm WLED

Aluminate with the magnetoplumbite-type (LaZnAl₁₁O₁₉) represents a big family technology important compound. Crystallographic sites for transition metal and rare earth ion in the magnetoplumbite structure have always been a hot topic. Here, manganese-based magnetoplumbite-type La(Zn,Mn)Al₁₁O₁₉ phosphors were successfully synthesized via the traditional solid-state reaction and all the samples crystallized into the hexagonal structure. A narrow green emission band at approximately 518 nm with quantum efficiency (～unit one) is demonstrated in LaZnAl₁₁O₁₉ host with Mn²⁺ doping equal 0.3. Temperature dependent photo-luminescence indicate that LaZn_0.7Mn_0.3Al₁₁O₁₉ sample keep excellent thermal stability. Meanwhile, the thermal ionization process was elaborated in detail. At last, a high-power w-LED with a high color rendering index and low associated color temperature is produced by inserting the microcrystals into the glass host using a “phosphor-in-glass (PiG)” technique.     

Highly translucent nanostructured glass-ceramic

Transparent and translucent glass-ceramics (GCs) are found in an increasing number of domestic and high-technology applications. In this paper, we evaluated and optimized the effects of two-stage heat treatments on the resulting crystalline phases and microstructure of a glass of the SiO₂–Li₂O–P₂O₅–TiO₂–CaO–ZnO–Al₂O₃ system. The objective was to develop a transparent nanostructured glass-ceramic (GC). After numerous heat treatment trials, we found that a long nucleation period of 72 h at 455 °C followed by a crystal growth treatment at 660 °C for 2 h resulted in a highly translucent GC having homogenously distributed nanocrystals. The relatively high amount of P₂O₅ (2.5 mol%) induced the formation of lithium disilicate as the main crystal phase. We thus developed a GC having crystals under 50 nm, with a high crystallized fraction (52%vol. Li₂Si₂O₅ and 26% vol Li₂SiO₃), transmittance of approximately 80% in the visible spectrum for 1.2 mm thick specimens, nano hardness of 8.7 ± 0.1 GPa (load of 400 mN), a high elastic modulus of 138 ± 3 GPa as measured by nanoindentation, and good flexural strength (350 ± 40 MPa) as measured by ball-on-3 balls tests. Due to its high content of Li⁺, this GC has the potential to be chemically strengthened and can be further developed to be used in a number of applications, such as on displays of electronic devices.     

Thermal cycling and ageing of a glass-ceramic sealant for planar SOFCs

Thermal cycling and thermal ageing tests were performed on Crofer22APU/glass-ceramic/Anode-Supported-Electrolyte (ASE) joined samples in air at the SOFC operating temperature of 800 °C. The Crofer22APU had been polished and preoxidised at 900 °C for 2 h. The diffusion behaviour at the two interfaces was examined and revealed slight diffusion of chromium and manganese from Crofer22APU into the glass-ceramic. No interactions, failure or crack formation were observed at the Crofer22APU/glass-ceramic interface and between the glass-ceramic and YSZ.     

Glass-ceramics of barium strontium titanate for high energy density capacitors

Barium strontium titanate glass-ceramics were successfully produced with one major crystalline phase when Al₂O₃ was added to the melt. A dielectric constant of 1000 and a breakdown strength of 800 kV/cm was achieved; however the energy density was only measured to be 0.3–0.9 J/cm³. These energy density values were lower than anticipated due to the presence of dendrites and pores in the microstructure. Using BaF₂ as a refining agent improved the microstructure and doubled the energy density for BST 80/20 samples. However, no refining agent reduced the increasing amount of hysteresis that developed with increasing applied electric field. This phenomenon is believed to be due to interfacial polarization.