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Article
Synthesis of Mullite Powder from Aluminum Nitrate and Precipitated Silica using Sol-Gel Process

Author: Hussein Alaa Jaber
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2016 Volume: 34 Issue: 8 Part (A) Engineering Pages: 1491-1498
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

In this work, a new route for possibility synthesizing high purity submicron size mullite (3A12O3.2SiO2) powder at relatively low temperature. Mullite precursor has been prepared from mixing precipitated silica powder with solution of aluminum nitrate nonahydrate (Al(NO3)3.9H2O) through sol-gel process, in order to obtain composite powder. The formed precursor gel was calcined at temperatures of (1100, 1150, 1200 and 1250)°C for 1 hour. The influence of calcination temperatures of the mullite synthesis was discussed. The microstructure tests of calcined materials were investigated by x-ray diffractometer (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDX). X-ray analysis results identified the mullitization initiated at 1200°C, and the mullite phase was completely formed at 1250°C. The SEM micrographs show the microstructure of mullite powder had been aggregated in the regular and nearly spherical-like appearances with diameters in the range of (100-200) nm.


Article
Effect of Glass Wool Addition on Some Properties of Cement Mortar

Author: Hussein Alaa Jaber
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2016 Volume: 34 Issue: 14 Part (A) Engineering Pages: 2685-2691
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

This work presents an investigation of possible incorporation of the glass wool (fiberglass insulation) in cement mortar as an insulating building material. Mortar of ordinary Portland cement of (1:3) cement to sand ratio was mixed with glass wool at different weight percentages ranged between (0 – 0.24) wt%. Density, water absorption, thermal conductivity, compressive strength and flexural strength experimentally were investigated for mortar specimens after curing for (28 days). The results showed that the incorporation of glass wool decreases the density, thermal conductivity and compressive strength, but the flexural strength of cement mortar enhances. Thermal conductivity of the cement mortar has decreased by about 44 % by increasing of glass wool content up to 0.24 wt%. Thus, utilization of glass wool as constituents in cement mortar appears to be a promising opportunity that enables applying as thermal insulation materials in constructions.


Article
Fabrication of Carbon Nanotube Reinforced Al2O3/Cr2O3 Nanocomposites by Coprecipitation Process
تصنيع متراكبات نانوية من Al2O3/Cr2O3 مدعمة بأنابيب الكاربون النانوية بأستخدام عملية الترسيب

Author: Hussein Alaa Jaber حسين علاء جابر
Journal: Al-Khwarizmi Engineering Journal مجلة الخوارزمي الهندسية ISSN: 18181171 23120789 Year: 2016 Volume: 12 Issue: 4 Pages: 93-101
Publisher: Baghdad University جامعة بغداد

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Abstract

In this research, the effect of multi-walled carbon nanotubes (MWCNTs) on the alumina/chromia (Al2O3/Cr2O3) nanocomposites has been investigated. Al2O3/Cr2O3-MWCNTs nanocomposites with variable contents of Cr2O3 and MWCNTs were fabricated using coprecipitation process and followed by spark plasma sintering. XRD analysis revealed a good crystallinity of sintered nanocomposites samples and there was only one phase presence of Al2O3-Cr2O3 solid solution. Density, Vickers microhardness, fracture toughness and fracture strength have been measured in the sintered samples. The results show that the relative density, microhardness and fracture strength of nanocomposites are significantly improved at low contents of Cr2O3 and MWCNTs. The increase of MWCNT’s content in the nanocomposites has adversely affected due to increasing the tangle and interaction of MWCNTs with each other, which leads to agglomeration in the nanocomposites. Increasing of Cr2O3 content in nanocomposites increases formation of Al2O3-Cr2O3 solid solution that actually requires the high sintering temperature to achieve good densification. The fracture toughness of Al2O3/Cr2O3-MWCNTs nanocomposites was enhanced by increasing the carbon nanotube content.

يتضمن هذا البحث دراسة تاثير اضافة انابيب الكاربون النانوية (MWCNTs) الى متراكبات نانوية من الومينا/كروميا (Al2O3/Cr2O3). حيث تم تصنيع متراكبات نانوية من الالومينا/كروميا-انابيب الكاربون النانوية مع محتويات مختلفة من Cr2O3 و MWCNTs باستخدام عملية الترسيب وتليها عملية التلبيد بالبلازما. كشف تحليل حيود الاشعة السينية ببلورية جيدة لعينات المتراكب النانوي مع تكون طور واحد للمحلول الجامد من Al2O3/Cr2O3. تم قياس الكثافة, صلادة فيكرز المجهرية, متانة الكسر ومقاومة الكسر للعينات الملبدة. اظهرت النتائج ان الكثافة النظرية, الصلادة المجهرية ومقاومة الكسر تحسنت بشكل ملحوظ عند محتويات منخفضة من Cr2O3 و MWCNTs. زيادة محتوى MWCNTs في المتراكب النانوي له تاثير سلبي ويرجع السبب الى زيادة التشابك والتفاعل لانابيب الكاربون النانوية مع بعضها, الامر الذي ادى الى التكتل في المتراكب النانوي. في حين ان زيادة محتوى Cr2O3 في المتراكب النانوي ادي الى زيادة تكون طور المحلول الجامد الذي احتاج الى درجات تلبيد عالية لتحقيق التكثيف الجيد. تحسنت متانة الكسر للمتراكبات النانوية مع زيادة محتوى انابيب الكاربون النانوية.

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