Advanced Materials Research Vol. 620

Abstract: Biphasic calcium phosphate (BCP) ceramic is a synthetic biomaterial exhibiting a chemical composition similar to that of tooth mineral. Therefore, it is viably used in coating metallic implants manufactured from metals and alloys, such as titanium and stainless steel. In the present study, electrophoretic deposition (EPD) has been attempted for depositing BCP coatings on 316L Stainless Steel substrate followed by vacuum sintering at 800 °C for 1 h. The surface morphology, thickness, compositions and microstructure of the BCP coated 316L SS was investigated by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and the bond strength of the coating was measured.

Abstract: Activated dolomite (AD), was investigated as a promising heterogeneous catalyst for the production of biodiesel. SnO₂ doped on activated dolomites catalyst (DSN) was synthesized through wet impregnation method and calcined at 500 °C for 3 h in air. The catalyst was then applied on biodiesel production via transesterification of palm cooking oil with methanol for required conditions (various time, oil to methanol ratio and amount of catalyst). X-ray Diffractometer (XRD), Brunauer-Emmet-Teller (BET) surface area, X-ray Fluoresence (XRF), Scanning Electron Microscopy (SEM) and Temperature Program Desorption (TPD) analysis were used to characterize the properties of the catalysts. Results showed that conversion of biodiesel by using DSN was higher (99.9 %) with lower optimum conditions i.e. 1:15 methanol to oil molar ratio, 1 wt. % of catalyst amount and reaction time of 6 h at 65 °C compared to AD (98.34 %) under higher conditions.

Abstract: Numerous methods have been used to produce high purity TiC. There is no previous study has been reported on the formation using single elemental powders of Titanium (Ti) and Carbon (C) with addition Nickel (Ni) by tungsten inert gas (TIG) weld method. In this work, TiC was synthesized via TIG method by arc melting elemental powder mixture of Ti and C at ~5 second (s) and 80 ampere (A). The effect Ni contents on TiC formation was investigated. The mixed raw material was ball milled for 24 hours followed by synthesis via TIG method. The arced samples were characterized by X-ray diffraction (XRD) and Scanning electron microscope (SEM). It was revealed, that small amount of Ni additive to the metal powder allows the production of dense and tough TiC.

Abstract: The present paper reports the polymeric sponge method of porous ceramic supports from porcelain mixtures. In this work, polyurethane (PU) foam with three different pore sizes have been selected, which are 100 ppi and 120 ppi as a substrate (support) and 10 ppi as an intermediate layer (catalyst support). In addition, the tubular support shape is selected, which its provide mechanical strength to intermediate layer and membrane layer to withstand the stress induced by the pressure applied over the whole supports. Tubular configuration has been produced by polymeric sponge method. The foam with 120 ppi has a positive effect on the porosity ratio of supports compared to those prepared from 100 ppi. Moreover, the influence of the sintering temperature on the total porosity, average pore size and compressive strength of supports has been investigated.

Abstract: Sago starch was mechanically treated with a stirring ball mill using anchoid as dispersing agent. Sago starch chemical modification was obtained from grafting copolymerization with polybutylacrylate (PBA) to reduce hydrophilic properties. The mechanical dispersed and chemical modified sago starches were studied through scanning electron microscopy (SEM), fourier transform infrared spectrometry (FTIR), and x-ray diffraction (XRD) analysis.

Abstract: Multiwalled carbon nanotubes/dolomite (MWCNT/dolomite) hybrid compound was synthesized using the Chemical Vapour Deposition (CVD) technique. The catalyst was prepared via the co-precipitation method. The process involves the drying of the precipitate followed by calcination at 900°C.Upon completion of calcinations process, the reduction process was carried under H₂ at 400°C and growth in a CH₄/N₂ gas mixture at 800°C for 30 minutes The reduction process was carried out under H₂ and growth in a CH₄/N₂ gas mixture at 800°C for 30 minutes. The morphological assessment using Field Emission Scanning Electron Microscope (FESEM) showed that the CNT was successfully grown on dolomite particle. High Resolution Transmission Electron Microscope (HRTEM) micrograph further confirmed the presence of MWCNT with varied length and geometry on dolomite surfaces, supported the formation of MWCNT on the dolomites particle.

Abstract: One of the promising and environmentally friendly hydrometallurgical processes for the recovery of manganese is acid leaching in the presence of carbohydrate as a reducing agent. The aim of this study is to characterize bamboo sawdust (BSD), in particular, the carbohydrate within, for possible usage as a reduction agent in acid leaching applications. Characterization were done using Malvern analyzer (particle size distribution), SEM (morphology), XRD (crystalline index) and FTIR (molecular framework). Detailed BSD constituents were also analyzed, to determine the cellulose, hemicellulose and lignin content. Results exhibited a wide size range distribution with a span value of 1.86, and geometric mean diameter of ~100 µm. The dominant composition, meanwhile, were cellulose (38.96%) hemicellulose (26.95%) and lignin (25.86%). The morphology characteristic by SEM revealed a smooth fibrous surface with multiple aligned bundles. The assessable crystalline index of cellulose was 56.12%. The molecular framework of cellulose, hemicellulose and lignin were clearly illustrated in BSD. The obtained characteristics are valuable information in utilizing BSD as a source of carbohydrate for leaching application.

Abstract: The TiO₂ anodized in organic electrolyte using 85% glycerol is used to investigate the crystalization of TiO₂ nanotubes annealed in air. The anatase start to form at 300°C and rutile appear when the temperature about 600 °C. The phase transformation is dependent on the annealing time and temperature. The anatase can be form at low temperatures when the annealing time is prolonged. The morphology of the annealed TiO₂ nanotubes changes as the function of the annealing temperature and the mechanism for the phase transformation of anatase to rutile is discussed.

Abstract: The equilibrium structure of muoniatedtetraphenylgermane (GePh₄Mu) was studied using the first principle Density Functional Theory (DFT) method. Three muonium (Mu) trapping sites were considered, namely ortho, meta, and para positions on one of the phenyl rings. Geometry optimization procedure was utilized to determine the local energy minimum for all the systems. The total energies corresponding to Mu at the three positions are very similar to each other. For the meta case, the corresponding energy is higher than the other two sites by only about 0.03 eV. The hyperfine parameters of Mu were also calculated. The Mu isotropic hyperfine coupling constants were found to be 441.85 MHz, 449.80 MHz, and 439.01 MHz for the ortho, meta, and para cases, respectively. The anisotropic value was calculated to be very small.

Abstract: In this work, 10 wt.% stainless steel (AISI304, FeCrNi) was used as a binder in WC-based hardmetal. Graphite powder (2 wt.%) was added in the mixture to avoid the formation of η-phase ((MW)₆C) during sintering. NbC with 1, 1.5, 2 and 5 wt.% was used as WC grain growth inhibitor. The sintering process was done in a vacuum furnace at 1300°C for 1h. The results showed that there was no formation of η-phase or free graphite after sintering indicating the suitability of added graphite. Increasing the NbC contents resulted in decreasing of WC grains. 2 wt.% NbC was considered to be the optimal content for fine microstructure and uniform WC grain distribution. The highest hardness was achieved at 2 wt.% NbC with HV₃₀ of 1660 kg/mm². However, higher amount of added NbC (5 wt.%) caused the existence of coarse (Nb,W)C grains which decreasing the hardness.