http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Samah S. Eldera (검색결과 1 건)
- 무료
- 기관 내 무료
- 유료
-
Samah S. Eldera,Reem Al-wafi,Omar A. Al-Harbi,Christian Rüssel,Esmat M. A. Hamzawy 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.11
A porous glass-ceramic enjoyed very low and negative thermal expansion was prepared. A glass of the base molar composition, 2 MgO·2 Al 2 O 3 ·2 B 2 O 3 ·5 SiO 2 with the addition of 1.61 ma% TiO 2 , was melted from kaolin, magnesite, silica sand and boric acid. The composition is based on cordierite where 50 % Al 2 O 3 were replaced by an equimolar concentration of B 2 O 3 . The glass was crashed and powdered, subsequently plastified, uniaxially pressed and finally sintered at temperatures in the range from 1100 to 1300 °C. X-ray diffraction of sintered samples gave evidence of a cordierite like crystalline phase. Scanning electron microscopy and electron dispersive microanalysis of samples prepared at 1300 °C showed crystals with hexagonal shape doped by TiO 2 , B 2 O 3 and Fe 2 O 3 embedded in a glassy matrix. With increasing crystallization temperature, the porosity of the glass-ceramics increased from 8.99 % (at 1200 °C for 3 min) to 56.42 % (at 1300 °C for 3 min). This led to a decrease of the specimen density from 1.9880 to 1.1278 g/cm 3 whereas the skeletal density increased from 2.1303 g/cm 3 to 2.5878 g/cm 3 . The microhardnesses were in the 5.60 and 6.00 GPa range. The coefficient of thermal expansion was between -3.26 and -2.27x10 -6 K -1 from room temperature up to 300 o C and -0.45 and 1.89x10 -6 K -1 from room temperature up to 500 °C. For the first time, to the best of our knowledge, a porous cordierite glass-ceramic with negative thermal expansion is reported. The partial replacement of Al 2 O 3 by B 2 O 3 enables to apply lower melting temperature which is advantageous for the production process.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
