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- 저자 : Bambang Sunendar Purwasasmita (검색결과 4 건)
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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.
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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.
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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 ℃.
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Dahlia Sutanto,Mieke Hemiawati Satari,Bethy S. Hernowo,Bambang Pontjo Priosoeryanto,Rifki Septawendar,Lia A. T. W. Asri,Bambang Sunendar Purwasasmita 한국세라믹학회 2020 한국세라믹학회지 Vol.57 No.5
Geopolymer and carbonated apatite are potential materials for dental restoration. We reported the synthesis of geopolymer– carbonated apatite nanocomposite, highlighting the infl uence of trace elements in carbonated apatite toward mechanical, leachability and cytotoxicity properties. Various carbonated apatites were combined with metakaolin, followed by geopolymerization. The study revealed that with addition of Mg 2+ and Sr 2+ , the geopolymer–carbonated apatite nanocomposites have the tendency to have lower mechanical properties. Geopolymer and geopolymer–carbonated apatite showed higher hardness, compressive strength, and modulus elasticity compared with geopolymer–carbonated apatite containing Mg 2+ and/ or Sr 2+ . Nevertheless, all samples showed mechanical properties that could be applied as dental restoration materials. Leaching assay confi rmed the release of Na + in all samples, originating from unreacted alkali activator. The Na + concentration decreased signifi cantly after 96 h of total washing, with the lowest value of 1 ppm. Cytotoxicity test was evaluated toward mouse embryonic fi broblast cells, indicating that all samples were not toxic to cells.
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