Preparation of nano mullite from activated kaolin and gibbsite at a low temperature

Suhanda Sutardi 한양대학교 세라믹연구소 2013 Journal of Ceramic Processing Research Vol.14 No.3

Nanomullite powders were successfully prepared from activated kaolin and gibbsite. Kaolin activation was performed by the thermal treatment at 800 o C and sulfuric acid treatment. The activation process has changed kaolin structure to produce alumina, silica, and aluminosilicate phases, as given by XRD result. The XRD result was corroborated and was proved by the result of electron diffraction TEM analysis, the activated kaolin consisted of a-Al2O3, quartz, and mullite phases. Nanomullite was prepared from the activated kaolin, gibbsit, and sulfuric acid and was calcined at 400 o , 600 o , 800 o , and 1200 o C. Crystallization of the as-prepared mullite in the temperature range of 400 o -1200 o C produced mullite, α-Al2O3, and spinel phases at 400 o C. A further phase transformation of the mullite sample maintained mullite and α-Al2O3 phases at 1200 o C. The grain sizes of mullitepowders are found to be less than 100 nm at a calcination temperature of 1200 o C. The electron diffraction (ED) patterns of the calcined mullite are indexed to the mullite phase with the crystal plane orientations of (310), (030), (101), (001), (201), (040) and (121). These results are in agreement with the XRD result for the calcined mullite at 1200 o C.

Roles of alumina, a base catalyst, a fine particle effect on the metastable phase Stabilization of the tetragonal zirconia at temperatures of 600-800 ℃

Rifki Septawendar,Suhanda,Soesilowati,Bambang Sunendar Purwasasmita 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.4

Nanoparticles of the tetragonal alumina-stabilized zirconia were synthesized from zirconium salt of ZrOCl2 • 8H2O and approximately 23 wt % alumina stabilizer with ammonia as a base catalyst and sucrose as a gelling agent at a room temperature. In the preparation process of nanoparticles of alumina-stabilized zirconia, the calcination was conducted at temperatures of 500-800 ℃. The calcined powder was analyzed and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) studies. The tetragonal phase of ZrO2 started to crystallize at a low temperature of 500 ℃. Further phase transformation of the alumina-stabilized zirconia maintained the tetragonal ZrO2 at 600 ℃. Besides, the addition of sucrose by weight ratio of 1 : 6 to the total weight precursors produced nanoparticles of alumina-stabilized zirconia less than 20 nm in size at that temperature. The tetragonal phase of ZrO2 was stable and no transition alumina was identified at 800 ℃. It is suggested that alumina is in solid solution in the tetragonal zirconia polymorph at that temperature. The typical SEM images show high agglomeration of ultrafine microstructures of alumina-stabilized zirconia nanoparticles at that temperature. The results indicate that the method represents an effective methodology for the preparation of alumina-stabilized zirconia nanoparticles at a lower temperature than 800 ℃.

Nanocrystalline α-Al2O3 powder preparation with sucrose as a template through a chemical route

Rifki Septawendar,Suhanda,Frank Edwin 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.4

Nanocrystalline α-Al2O3 powder was prepared through a chemical route via a reaction between aluminum nitrate nona hydrate with a sucrose template in variation ratios of the salt to the organic namely 1 : 2, 3 : 1, and 6 : 1 at a heating temperature of 200 oC. The homogenization process of the nanopowder was assisted by milling a“charcoal precursor” in a non polar solvent for 24 hours, which was then successfully calcined at temperatures of 900 oC and 1100 oC. The products were evaluated by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The optimum condition was obtained at a ratio of the aluminum salt to the organic compound of about 6 : 1, at a calcination temperature of 900 oC, which produced a 100% pure α-Al2O3 phase with a crystallite size of 44.6 nm. The SEM micrographs showed the particle sizes of nanocrystalline α-Al2O3 powders were found to be near 100 nm at 1100 oC. The TEM results indicate that nanocrystalline α-Al2O3 powders calcined at 900 oC had grain sizes below 50 nm. An increase of the sucrose concentration leads to smaller crystal sizes, meanwhile an elevation of the calcination temperature from 900 oC to 1100 oC leads to the formation of larger particle and crystal sizes of alumina.

Alumina phase transformation behavior on titania-doped nano α-alumina by a solid liquid process

Rifki Septawendar,Soewanto Rahardjo,Suhanda,Wisnu Hardik Pratomo 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.6

Alumina phase transformation behavior on titania-doped nano α-Al2O3 powder by a solid liquid process was investigated under various conditions, such as different solvent concentrations and calcining temperatures. Three batches of the precursor powders were calcined at three different temperatures of 600 oC, 750 oC and 900 oC for 5 h and a final product of titania-doped nano α-Al2O3 powder was obtained. The product has been identified by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The XRD results show that the alumina phases of the powders were determined to be γ-Al2O3 and α-Al2O3. The optimum calcination temperature of the precursor powder for crystallization of nano α-Al2O3 was found to be 900 oC for 5 h. A higher concentration of solvent used for the sample preparation leads to the formation of a uniform and very smooth particle morphology, and smaller particle grains. The TEM images indicate that the average size of α-Al2O3 grains was ≤ 50 nm and larger grains of TiO2 with 50-250 nm sizes.

Integrating ICT in the Sudanese Kindergartens by Means of Developing a Computerized Application for The Pre-School Education, In Order to Improve Cognitive Development:

MOHAMMED, AMGAD ATTA ABDELMAGEED,DRAR, SUHANDA SAFALDEEN MOHAMMED,HILAL, ANWER MUSTAFA,CHRISTENSEN, LARS RUNE International Journal of Computer ScienceNetwork S 2021 International journal of computer science and netw Vol.21 No.spc12

The current Sudanese preschool system depends on limited methods of education, children's education needs to be equipped to keep pace with technological development, also, the large gap that exists between the families and the Kindergartens, where many parents have no idea on how their child progresses in the KG context. The aim of this research is to integrate ICT in the preschool education to enhance and improve the preschool education, by building an Integrated Educational Application (Computerized Application for Preschool Education CAPE) which will help to improve the learning outcomes. The researchers used the Experimental Research Methodology, the characteristic of CAPE application is; suitable for children's age, the application style is more attractive to the children and contains a different way to help children get learning. Alawaeel and the Smart Child Kindergartens in Republic of Sudan were selected as a sample of the study, with sample size specifically, 50 children's. Also, the Central Bank of Sudan Kindergarten was selected as one of the institutional Kindergartens for easy communication with parents of children with a sample size 21 children. The study found that; using CAPE application in KG enables children to increase general learning effects and developing child's cognitive skills. Also, the children who were allowed to use CAPE by their parents are performed better in the overall evaluation of KG lessons. Also, using the CAPE in the Pre-School education helps the parents following their children's progress better and more reliable. The researcher recommends that to apply the computerized application and includes the second level. Also, converting the computerized program into an application to be used by children by their self, without the intervention of parents.

Effect of sugar and citric acid as precursors in ZrO2 nanopowder preparation at low calcination temperatures

Rifki Septawendar,Bambang Sunendar Purwasasmita,Suhanda Sutardi,Naili Sofyaningsih,Wahyudi Kristanto 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.3

Zirconia nanopowder was successfully prepared using sugar and citric acid by a precursor calcination process, in which sugar was used as a gelling agent and citric acid as a catalyst. The effect of citric acid on this zirconia preparation is found out by the variable time of addition of citric acid on the preparation, namely SZG (before sugar) and SGZ (after sugar). The calcinations were conducted at 600οC and 800οC. XRD results show that at 600οC, t- and m-ZrO2 phases are identified in SZG, whereas t-ZrO2 is the only phase in SGZ. XRD analysis finds that both of the zirconia samples having had crystallites below 20 nm. At a high temperature of 800οC, two phases of zirconia are identified as t- and m-ZrO2 in both of the samples with different intensities. A Quanta FEG SEM study shows both of the zirconia samples at 800οC have homogenous microstructures and grain sizes less than 100 nm. A high resolution sophisticated SEM investigation shows that the SZG sample at 800οC has an average grain size below 50 nm. However, the effect of the citric acid addition time on the zirconia preparation is clearly visible in the zirconia phase transformation. The earlier addition of citric acid on the preparation gives two phases of zirconia in the final product at 600οC; and by contrast, the later addition of the acid after sugar on the preparation produces only t-ZrO2 phase.

The zirconia phase transformation in the preparation of nano zirconia by calcining a gel-emulsion precursor

Hernawan,Rifki Septawendar,Naili Sofiyaningsih,Suhanda Sutardi 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.5

Nano-ZrO2 was succesfully prepared by calcining a precursor of a zirconium gel-emulsion in oleic acid. The gel-emulsion process was started with the preparation of a gel zirconium hydroxide. The hydroxide gel was then mixed with oleic acid at various ratios and heated at 200 oC to give zirconia precursors. These precursors were succesfully calcined at 800 oC, 1000 oC,and 1200 oC, to give zirconia powder. The crystal structure and the particle morphology of the calcined powder were identified using XRD, SEM, and TEM. The XRD results show that monoclinic zirconia is formed dominantly with crystallite sizes ranging from 46.2 to 55.3 nm at 800 oC. Meanwhile, the SEM micrographs of the zirconia calcined at 800 oC show particles with a homogenous morphology having sizes below 100 nm. The TEM results indicate that that the individual grain diameters of ZrO2 were less than 60 nm. A lower oleic acid concentration leads to a more alkaline condition and more monoclinic zirconia formed; and a higher calcination temperature leads to a larger size of crystallites.

Integrating ICT in the Sudanese Kindergartens by Means of Developing a Computerized Application for The Pre-School Education, In Order to Improve Cognitive Development:

MOHAMMED, AMGAD ATTA ABDELMAGEED,DRAR, SUHANDA SAFALDEEN MOHAMMED,HILAL, ANWER MUSTAFA,CHRISTENSEN, LARS RUNE International Journal of Computer ScienceNetwork S 2021 International journal of computer science and netw Vol.21 No.12

The current Sudanese preschool system depends on limited methods of education, children's education needs to be equipped to keep pace with technological development, also, the large gap that exists between the families and the Kindergartens, where many parents have no idea on how their child progresses in the KG context. The aim of this research is to integrate ICT in the preschool education to enhance and improve the preschool education, by building an Integrated Educational Application (Computerized Application for Preschool Education CAPE) which will help to improve the learning outcomes. The researchers used the Experimental Research Methodology, the characteristic of CAPE application is; suitable for children's age, the application style is more attractive to the children and contains a different way to help children get learning. Alawaeel and the Smart Child Kindergartens in Republic of Sudan were selected as a sample of the study, with sample size specifically, 50 children's. Also, the Central Bank of Sudan Kindergarten was selected as one of the institutional Kindergartens for easy communication with parents of children with a sample size 21 children. The study found that; using CAPE application in KG enables children to increase general learning effects and developing child's cognitive skills. Also, the children who were allowed to use CAPE by their parents are performed better in the overall evaluation of KG lessons. Also, using the CAPE in the Pre-School education helps the parents following their children's progress better and more reliable. The researcher recommends that to apply the computerized application and includes the second level. Also, converting the computerized program into an application to be used by children by their self, without the intervention of parents.

Nanocrystalline ZrO2 powder preparation using natural cellulosic material

Rifki Septawendar,Bambang Sunendar Purwasasmita,Suhanda,Leanddas Nurdiwijayanto,Frank Edwin 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.1

Nanocrystalline zirconia powder has been successfully prepared using a precursor calcination process involving hydrolysis of zirconium(IV) isopropoxide and utilizing Oryza Sativa pulp (Merang Pulp) as the cheapest natural template. The potential of Oryza Sativa pulp as a template in the preparation of nanocrystalline zirconia is investigated in this research. It is also shown that the presence of the pulp can produce zirconia in nanocrystallites because the agglomeration tendency has been reduced in the as-synthesized ZrO2 particles. The effect of the calcination temperature on this zirconia preparation is found out by variation of the applied calcination temperature. XRD characterization shows monoclinic zirconia as a fully dominant phase,and the largest ZrO2 crystallite is found to be 42.7 nm. However, the zirconia crystallite size will increase with an elevation of the calcination temperature.

Mineral phase, microstructure, and Infra-Red characteristics of calcia-stabilized zirconia nanocrystallines synthesized from local zircon and slaked lime

Dede Taufik,Mikrajuddin Abdullah,Hernawan,Suhanda Sutardi,Rifki Septawendar 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.10

Nanocrystallines of calcia-stabilized zirconia are known to reveal excellent mechanical and high ionic conductivity propertieswhose depend on the calcia concentration. In this work, nanocrystallines of calcia-stabilized zirconia were synthesized fromzircon precursor and 7.5 weight % CaO at 1000 oC, 1200 oC, and 1400 oC. Phase transformation and microstructure evolutionwere investigated by an X-ray diffraction and a scanning electron microscopy. Another un-doped zirconia was also synthesizedfrom the local zircon by following the same procedure for comparison. A fully cubic form of the calcia-stabilized zirconia andcalcium zirconate were obtained at 1200°C having the crystallite sizes ranging from 55 to 87 nm and remained stable at1400 oC. Meanwhile, un-doped zirconia consisted of pure the monoclinic zirconia at 1200 oC and 1400 oC. High agglomerationis found in the calcia-stabilized zirconia particles at 1000 oC, whereas grain boundaries and interconnect are observed at1400 oC. The cubic crystal of zirconia has specific and different finger print characteristics in the infra-red spectrum comparedto the monoclinic zirconia.