Formation of NaNbO3 Crystals in Dielectric Glass and Glass-Ceramics of a Na2O-Nb2O5-Al2O3-SiO2 System

2008 ◽  
Vol 55-57 ◽  
pp. 229-232 ◽  
Author(s):  
S. Thongsaeng ◽  
Anuson Niyompan ◽  
Rungnapa Tipakontitikul ◽  
Kamonpan Pengpat
Keyword(s):  
Heat Treatment ◽  
Treatment Time ◽  
Glass Ceramics ◽  
Glass Production ◽  
Nucleating Agent ◽  
Aluminum Silicate ◽  
Phase Identification ◽  
Dielectric Glass ◽  
Xrd Patterns ◽  
Glass Compositions

Dielectric glass and glass-ceramics were derived from Na2O-Nb2O5-Al2O3-SiO2 system. Small amount of TiO2 were also introduced into glass compositions to study crystallization behavior of the glass with present of this nucleating agent. Conventional melt-quenching technique was employed for a glass production and the selected bulk glass samples were subjected to the heat-treatment process at appropriate temperature. After six different glass compositions were produced, and by observation with necked eyes, all obtained glass samples are in light brown color and some samples were opaque due to crystallization took place during quenching. Phase identification through XRD patterns show that there were 3 phases, NaNbO3, NaNbO8 and a sodium aluminum silicate compound, found in those opaque glass samples. NaNbO3 is a predominant phase in all samples. Fortunately, clear transparent glass was obtained from the composition with no TiO2 addition. Heat treatment of this glass did not induce phase change, three aforementioned phases still present. Increasing heat treatment time promoted a higher of observed intensity of NaNbO3. But the NaNbO3 crystalline size was not significantly developed with time. The dielectric response of the NaNbO3 crystals in the glass-ceramics samples are influenced by presence of other crystalline phases.

Characteristics of Lithium Polysilicate Electrolyte Synthesized by Sol-Gel Processing

2007 ◽  
Vol 124-126 ◽  
pp. 1031-1034
Author(s):  
Bong Soo Jin ◽  
Bok Ki Min ◽  
Chil Hoon Doh
Keyword(s):  
Heat Treatment ◽  
Acid Treatment ◽  
Treatment Time ◽  
Sol Gel ◽  
Silicate Solution ◽  
Treatment Temperature ◽  
Lithium Silicate ◽  
Treatment Conditions ◽  
Xrd Patterns ◽  
Si Wafer

To find out suitable Si surface treatment and heat treatment conditions, acid treatment of Si wafer was done for lithium polysilicate electrolyte coating on Si wafer. In case of HCl treatment, the wet angle of a sample is 30o, which is the smallest wet angle of other acid in this experiment. Acid treatment time is 10 min, which is no more change of wet angle. Lithium polysilicate electrolyte was synthesized by hydrolysis and condensation of lithium silicate solution using perchloric acid. Thermal analysis of lithium polysilicate electrolyte shows the weight loss of ~23 % between 400 and 500 , which is due to the decomposition of LiClO4. The XRD patterns of the obtained lithium polysilicate electrolyte also show the decrement of LiClO4 peak at 400 . The optimum heat treatment temperature is below 400 , which is the suitable answer for lithium polysilicate electrolyte.

scholarly journals Effect of Saturated Steam Heat Treatment on Physical and Chemical Properties of Bamboo

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1999 ◽  
Author(s):  
Qiuyi Wang ◽  
Xinwu Wu ◽  
Chenglong Yuan ◽  
Zhichao Lou ◽  
Yanjun Li
Keyword(s):  
Heat Treatment ◽  
Moisture Content ◽  
Treatment Time ◽  
Flexural Modulus ◽  
Initial Moisture Content ◽  
Chemical Properties ◽  
Saturated Steam ◽  
Xrd Patterns ◽  
Physical And Chemical ◽  
Steam Heat

The aim of this study was to investigate the effects of the heat treatment time and initial moisture content of bamboo on the corresponding chemical composition, crystallinity, and mechanical properties after saturated steam heat treatment at 180 °C. The mechanism of saturated steam heat treatment of bamboo was revealed on the micro-level, providing a theoretical basis for the regulation of bamboo properties and the optimization of heat treatment process parameters. XRD patterns of the treated bamboo slices were basically the same. With the increase in the initial moisture content of bamboo, the crystallinity of bamboo increased first and then decreased after treatment. Due to the saturated steam heat treatment, the content of cellulose and lignin in bamboo slices increased while the content of hemicellulose decreased, but the content of cellulose in bamboo with a 40% initial moisture content increased first and then decreased. The shear strength of treated bamboo changed little within 10 min after saturated steam heat treatment, and then decreased rapidly. During the first 20 min with saturated steam heat treatment, the compressive strength, flexural strength, and flexural modulus of elasticity of the treated bamboo increased, and then decreased.

Manufacture of the Glass-Ceramics from the Lead-Zinc Tailings by Sintering

2014 ◽  
Vol 955-959 ◽  
pp. 2818-2823
Author(s):  
Xue Lian Ou ◽  
Yan Ping Guo ◽  
Gao Hui Zhong ◽  
Bao Qing Li ◽  
Ying Chen ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Crystalline Phase ◽  
Bending Strength ◽  
Orthogonal Experiment ◽  
Glass Ceramics ◽  
Nucleating Agent ◽  
Weight Losses ◽  
Glass Aggregate ◽  
Lead Zinc ◽  
Crystallization Heat

The glass-ceramics of CaO-Al2O3-SiO2system were prepared by sintering using lead-zinc tailings. Orthogonal experiment was carried out to optimize the ratio of lead-zinc tailings, chemical composition of basic-glass and other chemical materials in the system. Crystallization heat treatment conditions were confirmed by the differential thermal analysis (DTA) curve of glass aggregate. Crystalline phase, crystal morphology and mechanical property of the glass-ceramics samples were studied by means of X-ray diffraction (XRD), scanning electron microscope (SEM), hardness and bending strength test. The results indicated that the optimized ratio of the samples was lead-zinc tailings 25%, quartz 46.63%, calcite 21.05%, Al2O310.19% and nucleating agent TiO21%. The optimized crystallization heat treatment was that basic glass was first heated to 800 °C at 10 °C/min, then 800°C-900 °C at 5 °C/min and held still at 900 °C for 2 h. After that, the basic glass was heated to 1230 °C at 1-1.5 °C/min,held for 1h. At last, the glass-ceramics was obtained after the cooling-down of the system. The main crystalline phase of microcrystal glass-ceramics are diopside. The hardness and bending strength were 9.14 GPa and 213.6 MPa, respectively. The glass-ceramics had excellent chemical durability in acid and alkali solution, with weight losses of 0.17% and 0.68%, respectively.

Research on Processing Conditions of CBS Transparent Glass-Ceramics

2013 ◽  
Vol 873 ◽  
pp. 733-736
Author(s):  
Yi Min Wang ◽  
Hong Bo Zhang ◽  
Chun Hui Su ◽  
Qin Lei Wei
Keyword(s):  
Heat Treatment ◽  
Luminescence Property ◽  
Room Temperature ◽  
Glass Ceramics ◽  
Nucleating Agent ◽  
Processing Conditions ◽  
Transparent Glass ◽  
Melting Method ◽  
Heat Treatment Regime ◽  
Precursor Glass

On the basis of experimental verification, the optimum processing conditions of CaO-B2O3-SiO2(CBS) system transparent glass-ceramics were obtained. Composition of main raw powders (wt%) was:CaO 38%,SiO240%,B2O312%.The precursor glass was prepared by melting method and annealed at 560°C for 2h and cooled to room temperature at a speed of 5°C/min.The best nucleating agent is P2O5. The appropriate heat treatment regime to precursor glass was determined to be 2h at 600°C for nucleation and 3h at 780°C for crystallizition.Under this condition,the transmittion of glass-ceramics at the range of visable light is 72% in average and Sm3+keep good luminescence property doped in this host material.

scholarly journals Improved performances of lithium disilicate glass-ceramics by seeds induced crystallization

2020 ◽  
Author(s):  
Ting Zhao ◽  
Mei-Mei Lian ◽  
Yi Qin ◽  
Jian-Feng Zhu ◽  
Xin-Gang Kong ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Glass Powder ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Nucleating Agent ◽  
Comprehensive Properties ◽  
Aesthetic Appearance ◽  
Small Crystals ◽  
Bimodal Grain Size ◽  
Glass Compositions

Abstract Self-reinforced lithium disilicate (Li2Si2O5, LD) glass-ceramics were hot pressing sintered by introducing 5 wt% Li2Si2O5 crystal seeds into two different glass compositions of SiO2-Li2O-P2O5-ZrO2-Al2O3-K2O-La2O3 (7C LD) and SiO2-Li2O-K2O-La2O3 (4C LD). The results show that the seeds play an important role in the crystallization inducement, microstructural and properties improvement of the glass, especially for the glass powder without the nucleating agent of P2O5. The microstructure features a wider bimodal grain size distribution with large rod-like crystals epitaxially grown along the seeds and small crystals nucleated from the glass powder itself, contributes to the improvement of the performance especially the fracture toughness. The specimen of 4C LD glass with the addition of 5 wt.% Li2Si2O5 seeds exhibited the best comprehensive properties with a good flexural strength (396 ± 7 MPa), improved fracture toughness (3.31 ± 0.19 MPa·m1/2) and comparable translucency as IPS e.max. This research will provide a new idea and method for the improvement of the fracture toughness of lithium disilicate glass-ceramics without affecting its aesthetic appearance, and lay the foundation for its clinical applications.

Development of Machinable Glass-Ceramic without Nucleating Agents

2015 ◽  
Vol 830-831 ◽  
pp. 436-439
Author(s):  
C. Venkateswaran ◽  
Amarnath Padala ◽  
H. Sreemoolanadhan ◽  
M.R. Ajith ◽  
Mariamma Mathew ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
Heat Treatment Condition ◽  
Aluminum Silicate ◽  
Nucleating Agents ◽  
Treatment Conditions ◽  
Magnesium Aluminum Silicate ◽  
Optimum Heat ◽  
Alumino Silicate

Mica containing glass-ceramic is prepared by crystallizing magnesium alumino silicate glass between 600°C and 1100°C without the use of any additives or nucleating agents. Effects of ceramization heat treatment conditions on phase constitution and microstructures are analyzed using XRD and HRSEM respectively. Developed glass-ceramics have been analyzed for its microhardness and machinability. Optimum heat treatment condition for achieving uniformly distributed fluorophlogopite phase essential for machinability, and at the same time, magnesium aluminum silicate phase for increasing the hardness, is presented.

Influence of Thermal Treatment Temperature on Phase Formation and Bioactivity of Glass-Ceramics Based on the SiO2-Na2O-CaO-P2O5 System

2019 ◽  
Vol 798 ◽  
pp. 229-234 ◽  
Author(s):  
Puripat Kantha ◽  
Naris Barnthip ◽  
Kamonpan Pengpat ◽  
Tawee Tunkasiri ◽  
Nuttapon Pisitpipathsin
Keyword(s):  
Heat Treatment ◽  
Thermal Treatment ◽  
Phase Formation ◽  
Raw Materials ◽  
Glass Ceramics ◽  
Treatment Temperature ◽  
Phase Identification ◽  
X Ray Diffraction ◽  
Thermal Treatment Temperature ◽  
45S5 Glass

In this work, the thermal treatment temperature effect on phase formation and bioactivity of glass-ceramics based on the SiO2-Na2O-CaO-P2O5 system has been studied. The chemical composition of the system is 45 wt.% SiO2, 24.5 wt.% Na2O, 24.5 wt.% CaO and 6 wt.% P2O5 (45S5). The rice husk ash is used as the natural raw materials instead of commercial SiO2. All of the investigated compositions were prepared by melting the glass mixtures at 1350°C for 3 h. The resulting glass samples were heated at different thermal treatment temperatures ranging from 750 to 1050°C with fixed dwell-time for 4 h for crystallization. Phase identification of the 45S5 glass ceramics was carried out by X-Ray diffraction (XRD). Moreover, the physical properties such as density, porosity and mechanical properties were systematically investigated. It was found that, the increasing of heat treatment temperature led to the increasing of the Na2Ca2Si3O9 phase and obtaining better bioactive behavior after incubation of glass-ceramics in simulated body fluid (SBF) for 7 days. The maximum hardness value of 4.02 GPa was achieved after heating at 1050°C for 4 h. However, the density value has slightly changed with various heat treatment temperatures.

Surface Crystallization of ZnO-Al2O3-SiO2 Glass

2007 ◽  
Vol 280-283 ◽  
pp. 1655-1658
Author(s):  
Xiao Dong Li ◽  
Jie Mo Tian ◽  
Chen Wang ◽  
Li Min Dong
Keyword(s):  
Heat Treatment ◽  
Treatment Time ◽  
Glass Ceramics ◽  
Surface Crystallization ◽  
X Ray Diffraction ◽  
Crystalline Layer ◽  
Surface Conditions ◽  
X Ray ◽  
Treatment Processes ◽  
Electronic Microscope

ZnO-Al2O3-SiO2 glasses with different surface conditions were surface crystallized by different heat treatment process. Differential thermal analysis (DTA), X-ray diffraction analysis (XRD) and scanning electronic microscope (SEM) were used to investigate the crystallization behavior of glasses, the crystalline components and microstructure of the as-got glass-ceramics. According to the DTA results, different heat treatment processes of surface crystallization on the glass were adopted. The SEM results show that surface conditions of glasses are important for the surface crystallization, and the thickness of surface crystalline layer increases with heat treatment time.

Effect of Heat Treatment Time on Properties of Mica-Based Glass-Ceramics for Restorative Dental Materials

2016 ◽  
Vol 702 ◽  
pp. 23-27 ◽  
Author(s):  
Thapanee Srichumpong ◽  
Kallaya Suputtamongkol ◽  
Warat Chinpanuwat ◽  
Pronbadin Nampachoke ◽  
Jia Bai ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Crystal Size ◽  
Treatment Time ◽  
Dental Materials ◽  
Glass Ceramics ◽  
Nucleation Time ◽  
Human Enamel ◽  
Restorative Dental Materials ◽  
Dental Applications ◽  
Stage Heat Treatment

The objective of this research is to focus improving the properties of machinable mica-based glass-ceramics in order for restorative dental materials. The glass-ceramics derived from the SiO2- Al2O3-MgO-MgF2-SrCO3-CaCO3-CaF2-P2O5 system were produced by a two-stage heat treatment. It was elucidated that the optimum nucleation and the crystallization temperatures were at 643°C and 892°C. The various heat treatment times in the first stage were applied as 3, 6, 12, 24, 48 and 72 h, respectively, on the optimum nucleation temperature to produce mica-based glass-ceramics. XRD results showed that specimens of variety of nucleation time had similar crystalline structures such as calcium-mica, fluorapatite, stishovite, anorthite, strontiumapatite and forsterite phases. The microstructures of glass-ceramics were observed by SEM basically as interlocked plate-like and needle-like microstructures of mica and fluorapatite, respectively, in all specimens. Furthermore, different heat treatment times influenced on the revealed crystal size of the glass-ceramics; the longer heat treatment, the smaller crystals. The resultant glass-ceramics gave the results of biaxial flexural strength (178-224 MPa) and Vickers hardness (295-393 HV) increasing with the formation of the interconnected mica phases which contributed to improve the machinability. The values of the properties were comparable to those of human enamel and suitable for some restorative dental applications.

Sintering and Crystallization of Glass-Ceramics for Optical Fiber Ferrule

2007 ◽  
Vol 336-338 ◽  
pp. 1840-1842
Author(s):  
Y.M. Zhu ◽  
Xia Wan Wu ◽  
Zhi Hong Li
Keyword(s):  
Heat Treatment ◽  
Heat Treatment Temperature ◽  
Glass Powder ◽  
Treatment Time ◽  
Glass Ceramics ◽  
Treatment Temperature ◽  
Residual Glass ◽  
Sio2 Glass ◽  
Powder Compacts ◽  
Crystallization Of Glass

The crystallization and sintering of the Li2O-Al2O3-SiO2 glass powder compacts were studied. Results showed the relative densities of the sintered compacts with lower crystallization temperatures were higher than those with higher crystallization temperatures. A small amount of residual glass in the crystallized compact was good for sintering and densification. Compared with the heat treatment time, the heat treatment temperature was an important factor for the crystallization and sintering of glass powder compacts. The crystallized compacts with a small amount of residual glass should be sintered at a relatively higher heating rate under the prerequisite of keeping sintered compacts from deformation.

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