Effects of Different Content of TiO2 on Crystallization Behavior and Properties of Li2O-ZnO-SiO2 Glass-Ceramics

2014 ◽  
Vol 1035 ◽  
pp. 263-267
Author(s):  
Xiu Quan Zhao ◽  
Zheng Cao ◽  
Yu Teng Wu ◽  
Hong Jiang ◽  
Chang Jiu Li ◽  
...  

Glass-ceramic materials of the Li2O-ZnO-SiO2 system, with various amounts of TiO2 added, have been prepared. The appropriate heat treatment temperatures were selected according to the information provided by the differential thermal analysis (DTA). X-ray diffraction (XRD) analysis demonstrated that in the LZS glass-ceramics system, the main phases are Li2ZnSiO4, cristobalite, tridymite and quartz. The scanning electron microscopy (SEM) revealed that crystals appear as lamellar and spherical particles in the glass-ceramics samples. In addition, the average coefficient of the thermal expansion (CTE) values first decreased, then increased and finally tended to flatten. When the content of TiO2 increased to 6%, the CTE value decreased to 9.15×10-6/K, reached the lowest value. When the content of TiO2 increased to 10%, the CTE value reached highest value 13.90×10-6/K.

2014 ◽  
Vol 953-954 ◽  
pp. 1643-1648
Author(s):  
Hang Li ◽  
Li Qiang Liu ◽  
Min Jing ◽  
Zhi Gang Wang ◽  
Zheng Wang ◽  
...  

The glass-ceramic materials were produced from silicon slag with the addition of talcum powder and TiO2 by melting them in an electrically heated furnace and subsequent heat treatment at various temperatures and time. The microstructure and crystallization behaviors of glass–ceramics have been investigated by differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). With the increase of silicon slag content, the sequent precipitate phase is: krinovite Na (Mg1.9Fe0.1)Cr (SiO)3O, pseudobrookite Fe2TiO5 and anorthite Ca (Al2Si2O8), enstatite ferroan MgFeSi2O6, and albite Na (AlSi3O8). The shape of crystals was spherical grains. The glass–ceramic sample obtained from 70% silicon slag had the excellent mechanical performance including flexural strength of 200.45 MPa and Vickers micro hardness of 909.72 MPa.


2008 ◽  
Vol 368-372 ◽  
pp. 1426-1428
Author(s):  
Hong Xia Lu ◽  
Tie Cui Hou ◽  
Zhang Wei ◽  
Li Jian Li ◽  
Rui Zhang ◽  
...  

The characteristic of Angang blast furnace slag was studied by X-ray fluorescence spectrometry, DSC, X-ray diffraction and SEM. SiO2-Al2O3-CaO system glass-ceramics have been obtained successfully from slag with other additives. The properties of slag-based glass-ceramics were analyzed in this paper. It has been found that nucleation temperature is in the range of 600~700 °C, and crystallization temperature is in the range of 850~950 °C. The crystals phase is 2 CaO⋅ Al2O3⋅ SiO2. The chemical and mechanical properties of slag-based glass-ceramics are superior to the properties of clay brick.


2012 ◽  
Vol 1373 ◽  
Author(s):  
M. Garza-García ◽  
J. López-Cuevas ◽  
C.A. Gutiérrez-Chavarría ◽  
N. Piedad-Sánchez ◽  
E. Camporredondo-Saucedo ◽  
...  

ABSTRACTThe density, Vickers microhardness and crystallization fraction of glass-ceramic materials synthesized from parent glasses are determined in which CaO is gradually substituted by SrO. The chemical composition (in mol.%) of the parent glasses is 54SiO2-(23-X)CaO-12MgO-5Al2O3-6CaF2-XSrO, where X is the employed CaO substitution level (X = 0, 3, 6 and 9 mol.%, with X = 0 corresponding to the reference material). In order to determine the type of crystallization occurring in the glass-ceramic samples, as well as the crystalline phases formed in them, these are characterized by both Scanning Electron Microscopy (SEM/EDS) and X-Ray Diffraction (XRD). Independently of the CaO substitution level employed, the glass-ceramics show the formation of a solid solution corresponding to diopside-type pyroxene, with chemical formula Ca(Mg,Al)(Al,Si)2O6, as a single crystalline phase. The synthesized glass-ceramic materials with the reference composition show the highest Vickers microhardness and crystallization fraction, as well as the lowest density.


2003 ◽  
Vol 68 (6) ◽  
pp. 505-510 ◽  
Author(s):  
Branko Matovic ◽  
Snezana Boskovic ◽  
Mihovil Logar

Local and conventional raw materials?massive basalt from the Vrelo locality on Kopaonik mountain?have been used as starting materials to test their suitability for the production of glass-ceramics. Crystallization phenomena of glasses of the fused basalt rocks were studied by X-ray phase analysis optical microscopy and other techniques. Various heat treatments were used and their influences, on controlling the microstructures and properties of the products were studied with the aim of developing high strength glass-ceramic materials. Diopside CaMg(SiO3)2 and hypersthene ((Mg,Fe)SiO3) were identifies as the crystalline phases. The final products contained considerable amounts of a glassy phase. The crystalline size was in range of 8?480 ?m with plate or needle shape. Microhardness, crashing strength and wears resistence of the glass-ceramics ranged from 6.5?7.5, from 2000?6300 kg/cm2 and from 0.1?0.2 g/cm, respectively.


Cerâmica ◽  
2020 ◽  
Vol 66 (380) ◽  
pp. 413-420
Author(s):  
L. M. S. e Silva ◽  
R. S. Magalhães ◽  
W. C. Macedo ◽  
G. T. A. Santos ◽  
A. E. S. Albas ◽  
...  

Abstract Recycling has been pointed out as an alternative to the disposal of waste materials in industrial landfills. In the present study, the transformation of residues (discarded foundry sand - DFS, grits, and lime mud) in glass-ceramic materials is shown. The glasses were obtained by the melting/cooling method. The precursor materials, glasses, and glass-ceramics were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), and differential scanning calorimetry/thermal gravimetric analysis (DSC/TGA). The glassy materials were milled, pelleted, and thermally treated at the crystallization temperatures given by DSC data to obtain the glass-ceramics (885, 961, and 1090 ºC). The main formed phases were cristobalite, α-wollastonite (parawollastonite), and β-wollastonite (pseudowollastonite). The glass-ceramics showed very low water absorption and apparent porosity (0.26 to 0.88 wt% and 0.66 to 1.77 vol%, respectively). The results confirmed that the studied residues can be used as raw materials for the manufacture of vitreous and glass-ceramic materials.


2010 ◽  
Vol 92 ◽  
pp. 131-137 ◽  
Author(s):  
Qiu Hua Yuan ◽  
Pei Xin Zhang ◽  
Li Gao ◽  
Hai Lin Peng ◽  
Xiang Zhong Ren ◽  
...  

The crystallization behavior of MgO-Al2O3-SiO2 glass-ceramics by sol-gel technology was investigated by using x-ray diffraction (XRD), differential thermal analysis (DTA), Scanning electron microscopy (SEM). The results showed that: (1)α-cordierite phase was precipitated when the green body was calcined at 1050°C, and α-cordierite of high purity and stability could be formed at 1100°C; (2) Adding an appropriate amount of low melting point glass powder into the green body may provide liquid-phase environment during the sintering process, which will help enhance the tightness density of glass-ceramic, and thus improve its flexural strength.


2014 ◽  
Vol 46 (3) ◽  
pp. 353-363 ◽  
Author(s):  
F. He ◽  
Y. Zheng ◽  
J. Xie

The paper reports on some experimental results obtained from the production of glass-ceramics containing gold tailings powder (GTP). Frits particle sintered technology was used to prepare glass ceramic products. SiO2, CaO, ZnO, BaO and B2O3 were selected to adjust the composition of the glass. Based on the results of differential thermal analysis (DTA), the nucleation and crystallization temperature of parent glass samples with different schedule were identified, respectively. X-ray diffraction (XRD) analysis of the produced glass-ceramics materials revealed that the main crystalline phase was ?-wollastonite. With the increasing of CaO content, the intensity of crystal diffractive peaks also increases. The formation of ?-wollastonite crystal could be accelerated by the increasing of CaO. The glass-ceramics with fine microstructure showed better physical, mechanical properties and chemical resistance. Overall results indicated that it was a feasible attempt to produce glass-ceramics for building and decorative materials from waste materials. The amount of GTP used in the glass batches was more than 65 wt% of the whole raw.


2014 ◽  
Vol 8 (4) ◽  
pp. 203-210 ◽  
Author(s):  
Gamal Khater ◽  
Maher Idris

The crystallization of some glasses, based on celsian-spodumene glass-ceramics, was investigated by different techniques including differential thermal analysis, optical microscope, X-ray diffraction, indentation, microhardness, bending strengths, water absorption and density measurement. The batches were melted and then cast into glasses, which were subjected to heat treatment to induce controlled crystallization. The resulting crystalline materials were mainly composed of ?-eucryptite solid solution, ?-spodumene solid solution, hexacelsian and monoclinic celsian, exhibiting fine grains and uniform texture. It has been found that an increasing content of celsian phase in the glasses results in increased bulk crystallization. The obtained glass-ceramic materials are characterized by high values of hardness ranging between 953 and 1013 kg/mm2, zero water absorption and bending strengths values ranging between 88 and 126MPa, which makes them suitable for many applications under aggressive mechanical conditions.


1994 ◽  
Vol 353 ◽  
Author(s):  
Igor A Sobolev ◽  
Sergey V Stefanovsky ◽  
Fyodor A Lifanov

AbstractGlass-ceramic materials based on sphene, pyroxenes, apatite as well as various SYNROC formulations have been produced through melting in a laboratory electrically-heated furnace and inductive-heated melter (“cold crucible”). Materials prepared were investigated by X-ray diffraction analysis, electron-probe microanalysis, infra-red and EPR spectroscopies. Basic properties such as leach rates of radionuclides, density and compressive strength have been determined. Melted SYNROC-B and C phase compositions produced by induction melting are similar to hot-pressed SYNROC.


2012 ◽  
Vol 217-219 ◽  
pp. 119-123 ◽  
Author(s):  
Bao Wei Li ◽  
Hua Chen ◽  
Ming Zhao ◽  
Xue Feng Zhang ◽  
Yong Sheng Du ◽  
...  

Glass ceramics of the CaO-MgO-Al2O3-SiO2 system were fabricated by adopting the melting-casting procedure. Steel slag and fly ash were used as the major starting materials. The influence of CaO/SiO2 Ratio variations on the microstructure and mechanical properties were investigated using X-ray diffraction, scanning electron microscopy and property measurements. Augite is identified as the main crystalline phase of the as studied glass ceramics. The average size of augite grains in form of spherical particles is found within the range of 100-250nm. The bending strength of the glass-ceramics could reach as high as 170.74MPa. Increasing CaO/SiO2 show a beneficial influence on the crystallization of glass ceramics, and its effectiveness is inferior compared with that of increasing addition of nucleating agent, TiO2.


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