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RISS 인기검색어
- 검색키워드
- 저자 : Omar A. Al-Harbi (검색결과 2 건)
- 무료
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Fabrication of highly hydrophilic tubular type perlite membrane support
Omar A. Al-Harbi,Cem ÖZGÜR,M. M Khan 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.4
We fabricated and characterized a highly hydrophilic membrane support using only perlite as an ore without altering itschemical and physical properties. Tubular-type microfiltration supports were fabricated by an extrusion technique. Plasticperlite paste was obtained by adding organic additives and water. The extruded samples were carefully dried to prevent cracksduring the drying period of 6 days with a controlled drying temperature and humidity. Green bodies were sintered attemperatures of 1000 oC, 1025 oC, and 1050 oC for 1, 3, and 6 hours. Tubular membrane supports were characterized in termsof microstructure, porosity, pore size distribution and crystalline phases. Additionally, the hydrophilicity of the samples wasdetermined by a thin layer wicking (TLW) approach. The water contact angles of the samples sintered at 1025 oC for 3 hourswere determined to be 20 o, and the porosity and mean pore size of the sample were 23.54% and 13 µm, respectively. The cleanwater permeability of the sample was 10.677 L/h.m2bar. According to the results, the obtained sample functions well as a highlyhydrophilic membrane support, and it is also a good candidate for a filter used in macro- and microfiltration processes. Filtration tests indicated that the median particle size of the solids in waste water is 500 nm, with a turbidity of 100 NTU, andthe waste water can be cleaned by the newly fabricated perlite tubular ceramics up to a turbidity level of 0.35 NTU, whichis acceptable in various industries
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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.
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