Polishing aspheric mirrors of zero-thermal expansion cordierite ceramics (NEXCERA) for space telescope

2017 ◽  
Author(s):  
Jun Sugawara ◽  
Bumpei Mikashima ◽  
Tomohiro Kamiya
Keyword(s):  
Thermal Expansion ◽  
Space Telescope ◽  
Cordierite Ceramics

Germanium-Modified Cordierite Ceramics with Low Thermal Expansion

1986 ◽  
Vol 69 (12) ◽  
pp. 847-851 ◽  
Author(s):  
D. K. AGRAWAL ◽  
V. S. STUBICAN ◽  
Y. MEHROTRA
Keyword(s):  
Thermal Expansion ◽  
Low Thermal Expansion ◽  
Cordierite Ceramics

The Effect of Alumina (Al2O3) on the Characteristics of Sintered Mullite-Cordierite Ceramics Synthesized with Kaolin from Naratiwas of Thailand

2016 ◽  
Vol 690 ◽  
pp. 65-70 ◽  
Author(s):  
Santi Pongphot ◽  
Sakdiphon Thiansem
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Flexural Strength ◽  
Bulk Density ◽  
Suitable Condition ◽  
Length Change ◽  
Hydraulic Press ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Cordierite Ceramics

Mullite-cordierite ceramics was prepared by the three composition of talc, kaolin (kaolin from Naratiwas in Thailand) (NT) and alumina. The different amounts of alumina (5, 10, 15 and 20 wt%) were added to produce various mullite-cordierite alumina mixtures which are denoted as NA, NB, NC and ND, respectively. The mixtures were pressed into rectangular shapes by hydraulic press with the pressure of 150 kg/cm2 then sintered at temperature of 1300 °C and 1350 °C for 2 hours. The morphology of the synthesized mullite-cordierite samples were characterized by x-ray diffraction spectroscopy (XRD), and physical-mechanical properties were investigated. Mullite-cordierite was successfully synthesized. The XRD result was represented phases of mullite and cordierite. The NA samples sintered at temperature of 1300 °C indicated the best physical-mechanical properties including bulk density (2.23 g/cm3), flexural strength (44.4 MPa) and thermal expansion coefficients (5.00x10-6). The other NA samples sintered at temperature of 1350 °C exhibited the bulk density, flexural strength and thermal expansion coefficients are 2.21 g/cm3, 47.8 MPa and 4.99 x10-6, respectively. The thermal expansion coefficient of the NT sintered samples have been plotted the length change relative to measuring temperature ranging of 30-1200 °C. The suitable condition of the synthesized mullite-cordierite ceramics is finally obtained the NA samples with 5 percent weight of alumina composition sintered at the temperature of 1350 °C.

Effect of WO3 on the Performances of Cordierite Ceramics Synthesized by Using Kyanite as Raw Materials

2018 ◽  
Vol 281 ◽  
pp. 99-104
Author(s):  
Meng Li Qin ◽  
Xi Tang Wang ◽  
Zhou Fu Wang ◽  
Yan Ma ◽  
Hao Liu
Keyword(s):  
Thermal Expansion ◽  
Phase Composition ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Intermediate Phase ◽  
Raw Materials ◽  
Low Thermal Expansion ◽  
Cordierite Ceramics ◽  
The Right

In order to synthesize cordierite ceramics with low thermal expansion coefficient and good properties, in our work, the cordierite ceramics were prepared by using talc, natural containing zirconium kyanite, common kyanite and industrial Al2O3 as raw materials, introducing the right amount of WO3 (introducing tungsten acid) as catalyst. The effects of the introduced WO3 on the phase composition, sintering characters, microstructure and thermal expansion coefficient of the cordierite ceramics were investigated. The results show that the introduction of WO3 can eliminate the intermediate phase magnesia-alumina spinel and promote the formation of cordierite; the as-prepared cordierite ceramics synthesized by using natural containing zirconium kyanite as raw materials have high densification degree and low thermal expansion coefficient (1.53×10-6/°C, Rt~1000 °C).

Thermal Expansion of Cordierite Ceramics-Effects of Doping with Alkali and Heat Treatments

1988 ◽  
pp. 854-859
Author(s):  
H. Ikawa ◽  
T. Taniuchi ◽  
Y. Ushimaru ◽  
K. Urabe ◽  
O. Fukunaga ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Heat Treatments ◽  
Cordierite Ceramics
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