Property Control Of New Fluorinated Copolyimides And Their Applications

1991 ◽  
Vol 227 ◽  
Author(s):  
S. Sasaki ◽  
T. Matsuura ◽  
S. Nishi ◽  
S. Ando
Keyword(s):  
Refractive Index ◽  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Optical Waveguides ◽  
Fluorine Content ◽  
Optical Filters ◽  
Optical Transparency ◽  
Low Thermal Expansion ◽  
Property Control

ABSTRACTNew fluorinated copolyimides are synthesized with 2,2′-bis(trifluoromethyl)-4,4′- diaminobiphenyl (TFDB) and a mixture of 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and pyromellitic dianhydride (PMDA). The thermal expansion coefficient decreases with decreasing 6FDA content, because the hexafluoroisopropylidene group makes the main chain flexible. The refractive index decreases with increasing 6FDA content, because the fluorine content increases. The thermal expansion coefficient can be controlled between -0.5 × 10−5 and 8×10−5 /°C, and the refractive index can be controlled between 1.556 and 1.647 at 589.3 nm, by changing the 6FDA content. The polyimides and copolyimides from TFDB can be used in optical filters because of their high optical transparency and low thermal expansion coefficient. They are expected to be used in optical waveguides because of their high optical transparency and refractive index control.

Crystallization Behavior and Performance of MgO-Al2O3-SiO2 Glass-Ceramics by Sintering

2010 ◽  
Vol 92 ◽  
pp. 65-71 ◽  
Author(s):  
Pei Xin Zhang ◽  
Li Gao ◽  
Qiu Hua Yuan ◽  
Hai Lin Peng ◽  
Xiang Zhong Ren ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Flexural Strength ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Crystallization Process ◽  
Glass Ceramics ◽  
X Ray Diffraction ◽  
Low Thermal Expansion ◽  
Main Crystalline Phase ◽  
And Performance

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.

Study on Preparation of Low-Thermal Expansion Coefficient Concrete with Fly Ash

2014 ◽  
Vol 599 ◽  
pp. 89-92 ◽  
Author(s):  
Sha Ding ◽  
Zhong He Shui ◽  
Teng Pan ◽  
Wei Chen
Keyword(s):  
Thermal Expansion ◽  
Fly Ash ◽  
Pore Structure ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Cement Concrete ◽  
Thermal Expansion Property ◽  
Expansion Property ◽  
Low Thermal Expansion ◽  
Addition Level

The low-thermal expansion coefficient (CTE) of cement paste and concrete are designed and prepared with fly ash in this study. The thermal expansion property and pore structure of cement/concrete are tested by Thermal Dilatometer, MIP, and SEM. The test results show that the addition of fly ash lowers the thermal expansion rate and coefficient of hardened paste. The increase of addition level is accompanied by the decrease of the thermal expansion coefficient. The introduction of fly ash could improve the pore structure of concrete, thus improve the thermal expansion property of cement concrete.

Description of the PM Process by Using Ishikawa-Analysis

2013 ◽  
Vol 752 ◽  
pp. 48-56
Author(s):  
Andrea Simon ◽  
Károly Kovács ◽  
C. Hakan Gür ◽  
Tadeusz Pieczonka ◽  
Zoltán Gácsi
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Powder Metallurgy ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
High Strength ◽  
Manufacturing Technology ◽  
Low Density ◽  
Composite Manufacturing ◽  
Low Thermal Expansion

Composites are special material which can provide individual properties such as high strength with low density or good thermal conductivity with low thermal expansion coefficient. Composites conform to the constantly evolving and more complex expectations. In order to make a product with good quality, it is important to choose suitable materials and technology. In this research powder metallurgy (PM), as one of the most common composite manufacturing technology, was examined -which factors and mechanisms influence mostly the properties of the product. Ishikawa method was used to reveal these correlations.

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