Radiation-Induced Surface Deformation in Low-Thermal-Expansion Glasses and Glass-Ceramics

1988 ◽  
Vol 3 (6) ◽  
pp. 598-600 ◽  
Author(s):  
MOHAN RAJARAM ◽  
TSUNG-EIN TSAI ◽  
E. JOSEPH FRIEBELE
2010 ◽  
Vol 92 ◽  
pp. 65-71 ◽  
Author(s):  
Pei Xin Zhang ◽  
Li Gao ◽  
Qiu Hua Yuan ◽  
Hai Lin Peng ◽  
Xiang Zhong Ren ◽  
...  

The glass-ceramics of MgO-Al2O3-SiO2 system were prepared by sintering technology. The crystallization process of MgO-Al2O3-SiO2 glass-ceramics was investigated with X-ray diffraction (XRD), scanning electron microscopy (SEM), and other techniques; the discussion of breaking strength, thermal expansion coefficient and relevant properties at different sintering temperatures was also presented. The results show that: (1) The main crystalline phase isα-cordierite at different sintering temperatures, and the samples show high flexural strength and low thermal expansion coefficient; (2) with the increase of sintering temperature, the content of crystal phase increases, while the thermal expansion coefficient decreases evidently, the flexural strength and tightness density rise up first, then go down.


2019 ◽  
Vol 821 ◽  
pp. 435-439
Author(s):  
Bo Li ◽  
Ke Jing ◽  
Hai Bo Bian

Low temperature sintered MgO-Al2O3-SiO2 glass-ceramic with high mechanical and low thermal expansion was prepared for package. The remarkable influence of B2O3 addition on the electrical, mechanical, and thermal properties was fully investigated. A small amount of B2O3 promoted the sintering process and improved the densification of MAS. The kinetics via Kissinger method indicated that an appropriate B2O3 content decreased the activation energy and helped the occurrence of crystallization. Due to the increase of crystallinity and indialite phase, B2O3 addition significantly enhanced flexural strength and Young’s modulus. MAS doped with 3wt% B2O3 can be sintered at 900 °C and obtained good properties: σ = 229 MPa, φ = 86 GPa, α = 1.66×10-6 /°C, εr = 5.29, and tanδ = 5.9×10-4.


Two areas of development in the field of glasses and ceramics have produced new materials with unusual combinations of properties. Glass-ceramics are melted and formed as glasses by conventional glass-forming techniques, but by a subsequent heat treatment, they are converted to fine-grained crystalline structures with new and useful combinations of properties. Products with thermal expansion coefficients approaching zero and flexural strengths ranging from 10 000 to 50 000 Lb./in. 2 have been made though not all combinations of low thermal expansion coefficients and high mechanical strengths are possible. The second area of development is in so-called Chemcor glasses. Such glass products can be preferentially pre-stressed by chemical means so as to produce an outer layer with high compressive stress and a bending strength in the finished product up to 100 000 Lb/in. 2 .


2008 ◽  
Vol 39-40 ◽  
pp. 381-386 ◽  
Author(s):  
Akihiko Sakamoto ◽  
Yusuke Himei ◽  
Yoshio Hashibe

To survey new method for controlling thermal expansion of glass-ceramic material, we studied the coefficient of thermal expansion (CTE) and the microstructure of β-spodumene glass-ceramics. We found that the CTE of the β-spodumene glass-ceramics is remarkably reduced by introducing interstices at the boundary between the crystalline and glass phases. Despite its relatively low crystallinity (45vol%), a newly developed glass-ceramic showed an anomalous low thermal expansion of 7x10-7 /oC, which compares to that of silica glass. The mechanical strength of this glass-ceramic was at the same level as that of natural stones: marble and granite.


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