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THE IMPROVEMENT OF RAMIE FIBER PROPERTIES AS COMPOSITE MATERIALS USING ALKALIZATION TREATMENT: NaOH CONCENTRATION
Full text linkTHE IMPROVEMENT OF RAMIE FIBER PROPERTIES AS COMPOSITE MATERIALS USING ALKALIZATION TREATMENT: NaOH CONCENTRATION. Ramie fiber is a plant fiber that has good quality and potential as a constituent of composite materials. In this study, ramie fiber surface modification was conducted through alkalization with various at 0%, 4%, 5%, 6%, 7%, 8%, and 9% concentrations of NaOH using a magnetic stirrer with a speed of 200 rpm at 70οC for 5 hours. Alkaline ramie fibers are characterized using the Cheson method to determine the chemical composition of ramie fiber, FT-IR test to determine the function group of ramie fiber, morphological test to know the surface structure and diameter of ramie fiber, as well as tensile test to know the tensile strength and tensile modulus of PLA/ramie composite. Overall, the increase of NaOH concentration up to 8% percentage was able to increase the level of cellulose and lignin ramie fibers by 88.180 % and 2.444 %, as well as lower hemicellulose levels of 1.446 %. The alkalization treatment of 8% NaOH, optimally reduces the hydrophilic properties of the fiber. The increased concentration of NaOH makes the fiber surface cleaner and the diameter smaller, but the fiber structure is damaged at a concentration of NaOH more than 8%. Tensile test results showed that alkalized ramie fibers with an 8% concentration of NaOH produced PLA/ramie composites with the highest tensile strength and tensile modulus of 57.37 MPa and 248.25 MPa. Thus, the optimum ramie fiber properties are increased using alkalization with an 8% concentration of NaOH
SYNTHESIS AND CHARACTERIZATION: COMPOSITE OF GRAPHENE OXIDE BASED PALM KERNEL SHELL WASTE WITH FE3O4
Full text linkSYNTHESIS AND CHARACTERIZATION: COMPOSITE OF GRAPHENE OXIDE BASED PALM KERNEL SHELL WASTE WITH Fe3O4. In this study, GO-Fe3O4 were fabricated by co-precipitation technique and the graphene oxide (GO) were synthesized from an agricultural biomass, palm kernel shell, via Hummer’s method. Field Emission Scanning Electron Microscopy and Energy Dispersive Spectrum (FESEM-EDS), Fourier Transform Infra-Red (FT-IR) spectroscopy, X-Ray Diffractometer (XRD), and Raman spectroscopy were used to analysis the successful attachment of Fe3O4 onto the surface of GO. Morphology observation showed that Fe3O4 were heterogeneously deposited on the surface of GO. FT-IR spectra shows peak that incorporated to oxygenated functional groups and sharp peak at 586 cm-1 confirmed to lattice absorption of Fe3O4. The percentage of composition of GO-Fe3O4 was characterized by energy dispersive spectroscopy and the results also confirmed in XRD exhibits similar properties with JCPDS 19-0629 for magnetite more dominant than GO. From Raman spectroscopy analysis shows that 1343.82 cm-1 (D-band) and 1584.62 cm-1 (G-band) and 2698 cm-1 (2D-band) indicates GO and GO-Fe3O4 were successfully synthesized
STUDY ON THE EFFECT OF COMPOSITION AND VARIATION OF Sn/Zn COOLING MEDIA ON NICKEL ALLOY STEEL THROUGH HOT FORGING AND AUSTEMPERING
Full text linkSTUDY ON THE EFFECT OF COMPOSITION AND VARIATION OF Sn/Zn COOLING MEDIA ON NICKEL ALLOY STEEL THROUGH HOT FORGING AND AUSTEMPERING. Laterite steel with nickel content is expected to be a solution to overcome the lack of domestic steel availability and dependence on imports. This research was conducted to develop Nickel-Chromium-Molybdenum alloy steel used Grinding ball for cement industrial applications. Grinding ball is the one of imported steel products needed to be crushing and size reduction the ores or cement. In addition to import issues, grinding balls have a significant problem: their mechanical properties that do not meet SNI 1049 require the material to have a minimum hardness value of 45 HRC. In this study, the characteristics of Nickel alloy steel were investigated further through heat treatment of forgings heated at the austenitizing temperature of 950 °C and austempering with variations in the cooling medium of Sn/Zn solution. The cooling medium was chosen because it has a melting temperature in the phase diagram area to form the bainite microstructure with complex and challenging characteristics, both of which are required in material for grinding ball applications. In particular, the hardness value that passed the SNI 1069 standard was the use of samples with a Cr-Mo alloy of 1%-wt with a hardness value of 45.92 HRC for Sn Austemper and 48.07 HRC for Zn austemper
THE STRUCTURAL, IMPEDANCE AND DIELECTRIC A FERRITE CORE OF IRON MANGANITE AND ITS COMPOSITE
Full text linkTHE STRUCTURAL, IMPEDANCE AND DIELECTRIC A FERRITE CORE OF IRON MANGANITE AND ITS COMPOSITE. Samples with single-phase MnFeO3 and multiphase MnFeO3/ZnFe2O4 (30/70), and MnFeO3/ZnFe2O4/LaMnO3 (30/40/30) have been successfully prepared as ferrite cores by the solid-state reaction method using high energy milling. Crystal structure, surface morphology, impedance, AC-conductivity and dielectric quantities, such as dielectric constant and dielectric loss have been studied. The crystalline structures for MnFeO3, ZnFe2O4, and LaMnO3 are hexagonal, cubic and monoclinic, The Rietveld program used for XRD analysis resulted in the composition fractions of single phase MnFeO3, multiphase MnFeO3/ZnFe2O4 (31/69), and MnFeO3/ZnFe2O4/LaMnO3 (31/40/29). The morphology of all samples has a heterogeneous shape and size with low porosity. The single-phase impedance of MnFeO3 is higher than the multiphase sample. The conductivity of the three samples has the same pattern, which is relatively constant at low frequencies and begins to increase at frequencies above 10 kHz. The dielectric constant and dielectric loss (tan ) have high values at low frequencies, decrease exponentially with increasing frequency and are relatively fixed at high frequencies
A SYNERGISTIC ABSORPTION AND PLASMONIC EFFECT OF SiO2@Au@TiO2 IN TiO2 PHOTOANODE FOR DYE-SENSITIZED SOLAR CELLS
Full text linkA SYNERGISTIC ABSORPTION AND PLASMONIC EFFECT OF SiO2@Au@TiO2 IN A TiO2 PHOTOANODE FOR DYE-SENSITIZED SOLAR CELLS. A method for increasing the visible-light harvesting of a TiO2 anatase photoanode in dye-sensitized solar cells by incorporating plasmonic nanostructures was developed. Sidoarjo mud as the SiO2 source was used to successfully synthesized core/multishell SiO2@Au@TiO2, with varying amounts of Au (60, 90, and 120 mL). In addition, the core/multishell fractions in TiO2 paste were varied, i.e., 0.5%, 1%, and 5%. The UV–Vis spectrum shows that a more ripple spectrum at higher wavelengths is obtained with increasing Au content, as suggested by the presence of large Au nanoparticles; however, a similar value of efficiency is observed for all sample variations studied compared to a pure TiO2 photoanode. The incident photon-to-current efficiency reveals that all photoanodes containing the core/multishell SiO2@Au@TiO2 studied show somewhat broader and enhanced spectra for all studied wavelengths compared to the pure TiO2 photoanode, resulting from the synergistic effect between plasmonic nanostructures and the presence of silica that boost the absorption to higher wavelengths
PENGARUH METODE PEMISAHAN PELARUT DALAM GEL TERHADAP SIFAT FISIK TITANIA-ALUMINA SEBAGAI PENYANGGA KATALIS
Full text linkPENGARUH METODE PEMISAHAN PELARUT DALAM GEL TERHADAP SIFAT FISIK TITANIA-ALUMINA SEBAGAI PENYANGGA KATALIS. TiO2-Al2O3 gel monolitik dalam nisbah mol 0,2 untuk TiO2 dan 0,8 untuk Al2O3 telah dibuat dengan cara hidrolisis dari aluminium sec-butoksida, Al (OC4H9sec)3 dan titanium isopropoksida Ti(OC3H7iso)4 dalam larutan n-propanol dengan katalis asam. Pemisahan pelarut dalam gel dilakukan dengan dua cara, pertama pengeringan pada tekanan atmosfer hingga terbentuk xerogel. Kedua, pemisahan pelarut pada kondisi CO2 superkritik, hingga terbentuk aerogel. Terbentuknya gugus Ti-O, salah satu dari titanium dioksida atau jaringan polimer –Ti-O-Ti-O-Al-O- ditunjukkan dengan adanya puncak antara 500 dan 900 cm-1 yang tajam tetapi lebar pada spektrum infra merah. Puncak yang kuat pada 1635 cm-1 menandakan adanya gugus –OH uluran yang merupakan derajat yang tinggi dari permukaan hidroksilasi. Volume kumulatif pori-pori dari xerogel sangat kecil jika dibandingkan dengan aerogel hasil pemisahan pelarut pada kondisi CO2 superkritik. Fase anatase TiO2 tidak terbentuk selama proses kristalisasi hingga kalsinasi sampai suhu 1000oC. Pengkristalan alumina terjadi secara langsung dari fasa amorf Al2O3 ke fasa α-Al2O3 dan fasa-fasa antara θ- dan γ-Al2O3 tidak teramati. Dari hasil tersebut dapat diperkirakan bahwa selama kalsinasi partikel TiO2 terpisah dari partikel Al2O3 membentuk inti atom rutil sebelum terbentuknya kristal α-Al2O3. Karena itu pembentukan fasa rutile TiO2 akan mempercepat terbentuknya fasa α-Al2O3. Keasaman campuran titania alumina setelah dikalsinasi pada suhu 500 oC lebih tinggi daripada oksidanya masing-masing, yaitu TiO2 dan Al2O3. Hal ini disebabkan oleh terbentuknya asam Lewis dari campuran titania-alumina
IDENTIFICATION OF BAINITE IN A MULTI-PHASE MICROSTRUCTURE OF AN AUSTEMPERED STEEL ALLOY: A METALLOGRAPHY APPROACH
Full text linkIDENTIFICATION OF BAINITE IN A MULTI-PHASE MICROSTRUCTURE OF AN AUSTEMPERED STEEL ALLOY: A METALLOGRAPHY APPROACH. Structural characterization of a multi-phase steel has become an exciting issue in various studies to date. This relates to the difficulty in distinguishing phases with similar morphology, i.e. bainite and martensite, through chemical etching. This study discusses a method to observe bainite phase through a metallographic approach on FeNi steel using color etching. Variations in the use of etching in this research include 2% nital, 4% picral, and 15% sodium metabisulphite (SMB). First, the samples were austenized then austempered at either 400 °C or 500 °C, for 60 min followed by quenching in either water or brine solution. Based on optical microscope observations, SMB color etching provides more explicit information on the visualization of bainite and martensite phases because they have different color appearances. The bainite phase is shown in bluish color, while the martensite phase is shown in brownish color. Furthermore, the influence of variation in austempering temperature and quench media on microstructure morphology was also discussed. In addition, the calculation of the lattice parameters of the X-Ray Diffraction (XRD) pattern was also carried out in this study to identify the crystal structure formed
NANOSTRUCTURED ALLOYS AND MECHANICAL ALLOYING
Full text linkNANOSTRUCTURED ALLOYS AND MECHANICAL ALLOYING. This paper reviews the formation of nanostructured alloys, recent development of nanocrystalline magnesium alloys and their nanocomposite synthesized via mechanical alloying. Though mechanical alloying was developed for the processing of oxide dispersion strengthening super-alloys, this technique offers the possibility of producing very fine crystallite size down to the nano-scale with flexibility in alloying so that the mechanical properties of the final composite can be tailored