Long-lasting luminescent ZnGa2O4:Cr3+ transparent glass-ceramics

2014 ◽  
Vol 2 (46) ◽  
pp. 10002-10010 ◽  
Author(s):  
Sébastien Chenu ◽  
Emmanuel Véron ◽  
Cécile Genevois ◽  
Alain Garcia ◽  
Guy Matzen ◽  
...  

Highly transparent ZnGa2O4 glass-ceramic materials, showing red long-lasting luminescence arising from the entire sample volume, are reported.

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.


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.


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.


1987 ◽  
Vol 2 (6) ◽  
pp. 801-804 ◽  
Author(s):  
D. R. Clarke ◽  
B. Schwartz

The utilization of transformation toughening has hitherto been restricted to increasing the fracture resistance of polycrystalline ceramic materials. Although a number of investigators have attempted to extend the concept to toughening glasses and glass ceramics with tetragonal zirconia, no successful reports have been published. It is argued that the approaches employed are inevitably limited primarily because they do not take into account the necessity of nucleating the tetragonal-to-monoclinic transformation away from the crack tip itself. By concentrating on the nucleation event and using standard ceramic processing techniques, it has been demonstated that transformation toughening can be used to increase the toughness of glass-ceramic materials, and this approach is illustrated by increasing the fracture toughness of a cordierite glass ceramic.


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