Solid State Phenomena Vol. 302

Abstract: Stainless steel is widely utilized due to its higher corrosion resistance and gloss than ordinary steels. However, the applications of stainless steel are still limited because of its low surface hardness. Graphene is a superb material, which has an intrinsic strength of 130 GPa. In this report, the growth of high quality graphene on S304 stainless steel by chemical vapor deposition using acetylene gas as a carbon source is demonstrated. The surface hardness of stainless steel after growing high quality graphene is investigated by nanoindentation technique. High quality graphene can increase the surface hardness of stainless steel from 1.54 GPa to 10.08 GPa. Moreover, the effect of graphene quality on the surface hardness of S304 stainless steel is studied. High quality graphene grown by CVD using acetylene gas as a carbon source can increase the surface hardness of stainless steel about two times more than low quality graphene grown by using methane gas.

Abstract: The purpose of this work was to study the microstructure and the mechanical properties of the fiber-reinforced cement composites that used the nucleating-agent activated coal-fired power plant bottom ash as a raw material in the mixture for producing the composites. The raw materials for producing the fiber reinforced cement composites were the ordinary Portland cement (OPC), natural gypsum, cellulose fiber, and bottom ash. The bottom ash was chemically treated by the nucleating agent, a chemical that was prepared by the precipitation process from the aqueous solutions of sodium silicate (Na₂SiO₃) and calcium nitrate (Ca (NO₃)₂). To prepare the samples, the mixture consisting of 34.75 wt% OPC, 34.75 wt% bottom ash, 25 wt% natural gypsum, and 5.5 wt% cellulose fiber was mixed with the nucleating agent at the amount of 0 to 4.5 % of OPC weight in the mixture, and water to form the slurry. Then, the samples were produced by filter pressing process and cured in the autoclave for 16 hrs at 180 °C, and 10 bars. The mechanical properties of the samples including modulus of rupture (MOR), modulus of elasticity (MOE), and toughness were characterized by the universal testing machine (UTM). The microstructures of the samples were observed by scanning electron microscope (SEM). The results showed that the utilization of nucleating agent affect the microstructure of the sample leading to the improvement in the mechanical properties of samples.

Abstract: The aim of this work is to study the feasibility of recycling the rejected fiber-cement composites as the filler in the fiber-cement mixture for producing the new fiber-cement composites. The rejected fiber-cement composites were ground and mixed with ordinary Portland cement (OPC), sand, cellulose fiber, and the dissolving agent which was a chemical prepared from the proprietary blend of citric acid together with thickening and wetting agent. The samples (75 mm × 200 mm × 7 mm) were prepared by mixing the raw materials, including 34.25 wt% OPC, 30 wt% sand, 5.5 wt% cellulose fiber, and 30.25 wt% recycled fiber-cement composites. Then, the dissolving agent was added in the amount of 0 to 4.5 % of the OPC weight in the mixture. The mixtures of raw materials were mixed with water to form the slurry. Then, the green samples were produced by the filter pressing method. After molding, the green samples were autoclaved at pressure 10 bars and temperature 180 °C for 16 hrs. After that, the microstructure of the autoclaved samples was examined by scanning electron microscope (SEM). The modulus of rupture (MOR) and modulus of elasticity (MOE) of the samples were measured by universal testing machine (UTM) based on ASTM C1186-08 standard. The results showed that properties of the samples passed the requirements of the industrial standard. In addition, the utilization of dissolving agent affects both the microstructure and the properties of the samples.

Abstract: The aim of this research was to study the properties of cement reinforced with coconut fiber. The coconut fiber addition that uses in this research were 5, 10 and 15% by weight of cement. The cement paste and coconut fiber were mixed together and packed into an iron mold. Then, the specimens were kept at room temperature for 24 hours and were moist cured in the water bath at 3, 7 and 28 days. After that, the physical properties i.e. water absorption and density were examined. The microstructure was characterized by scanning electron microscopy (SEM). The results showed the surfaces of the coconut fibers were not smooth, spread with nodes and irregular stripes, which is covered with substances and other impurities. The compressive strength and flexural strength were also investigated. From the results, the mechanical properties were decreased with increasing coconut fiber content due to reducing density and higher porosity and water absorption compared to non-fiber cement paste and physical properties of fiber had been flexibility and smoother caused poor binding with cement. The best compressive strength and flexural strength results were obtained with the percentages of coconut fiber as 5% which value as 26.67 N/mm² and 5.08 N/mm² respectively.

Abstract: Mesoporous silica (MPS) is a porous silica material with various pore structures. In this study, mesocellular foam silica (MCF) was synthesized and functionalized by hexamethyldisilazane (HMDS) to study effects of surface chemistry on benzene adsorption capability. Physical and chemical properties of pristine and functionalized MCFs were characterized and compared. Scanning and transmission electron microscopy showed that the complex pore structures of the MCFs were retained after the functionalization at relatively high temperature (573K). TGA and FTIR results showed that the functionalization led to a reduction of water adsorbed on the surfaces of the MCF. The functionalization improved adsorption of benzene compared to the pristine MCF and the optimum HMDS:SiO₂ molar ratio was 1.5. The amount of benzene adsorbed has a linear relationship with the concentration of benzene in the environment. This relationship enables quantitative benzene detection by using the functionalized MCF as sensing materials in resistive-type or gravimetric-type benzene gas sensors.

Abstract: In this research, the Ba(Zr_0.05Ti_0.95)O₃ powders were prepared by molten salt method. The powders were calcined at 600-1100°C for 3 h with heating rate of 5°C/min. The BZT powders were synthesized by molten salt method to reduce the calcination temperature by up to 300°C. The sintering procedure was carried out at 1250°C for 2 h with a heating/cooling rate of 5°C/min. Phase formation and microstructure were examined by XRD and SEM, respectively. The influence of the CuO additive on density and dielectric properties were investigated. The density of the sintered samples was measured by Archimedes method with distilled water as the fluid medium. Dielectric properties were examined by LCR meter. The BZT+2.0 mol% CuO ceramic sintered at 1250°C showed the highest density of 5.76 g/cm³, and the room temperature dielectric constant and dielectric loss at 1 kHz were 2687 and 0.01, respectively.

Abstract: Synthesis routes of CoSb₃ need a long reaction time, especially at high temperature and-/or high pressure. Although the modified polyol process assisted with microwave radiation can be used to solve these problems, it used the excess amount of Sb ion. Therefore, this study aimed to solve this drawback by retarding the rate of reduction. The different microwave times (0, 1, and 3 min) were investigated to find out the shortest heating duration for preparing CoSb₃ nanoparticles. Te-doped and Sn-doped CoSb₃ were synthesized to investigate the benefit of this synthesis method for increasing the solubility limit of Te and Sn in the CoSb₃ structure. The phase and microstructure of the synthesized products were characterized by using x-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results showed that the high crystalline phase of CoSb₃ (JCPDS: 78-0977) without any metallic impurity phases product was successfully synthesized in 3 minutes for a heating time at normal pressure, non-excessive addition of Sb ion precursor, and low temperature. The XRD results of Te-doped and Sn-doped CoSb₃ products exhibited poor crystalline phase and hard to exactly identify. In SEM and TEM results, the CoSb₃ powder consisted of very tiny spherical-like particles around 10 nanometers attaching together even at different microwave time similar to Te-doped/Sn-doped samples.

Abstract: Porous materials are attractive in various applications such as energy storage and production, industrial processing, environmental treatment, and catalysis. Porous LaCoO₃ was prepared using three different metal precursor solutions: i) 40%v/v methanol-ethylene glycol (40%Me/EG), ii) Lysine (Lys), and iii) Lysine/citric acid (Lys/Cit) with poly(methyl methacrylate) colloidal crystal as porous templates (PMMA-CCT). PMMA-CCT filled with metal precursor solution were carbonized under N₂ followed by oxidized under 50% O₂ in N₂ atmosphere. X-ray diffraction patterns of the obtained porous LaCoO₃ are rhombohedral LaCoO₃ phase without impurity. The scanning electron microscopy (SEM) was carried out to examine the morphology of porous LaCoO_3. The SEM image of the LCO-Lys/Cit exhibits better connected particles and a well-defined pore structure compared to those prepared by Lys or 40%Me/EG metal precursor solutions. The evolution of pore formation of LCO-Lys/Cit was investigated by SEM, Fourier transform infrared spectroscopy (FT-IR), and thermal gravitational analysis (TGA). The materials show high catalytic properties for the electrochemical water oxidation reaction. The high capacitances of all porous LaCoO₃ are attributed to the controlled three-dimensional porous morphology of the catalysts. This synthesis approach can achieve porous materials with promising properties for catalysis applications.

Abstract: Peat can be used as a natural adsorbent due to its humic acid content having various active functional groups such as carboxylates and hydroxyl groups. Peat soil samples obtained from Pelalawan district, Riau province of Indonesia were selected and their adsorption capacities were investigated using Mn(II) solution as a model solution. The raw peat samples were first prepared by drying at 110°C for 12 h. The adsorption experiment was conducted in batch test using Mn(II) solutions for 360 mins at pH of 5.2 as optimum conditions. The peat samples were analyzed using the Fourier Transform Infrared Spectroscopy, Surface Area Analysis and Scanning Electron Microscopy- Energy Dispersive Spectroscopy. The obtained adsorption data were fitted using Langmuir, Freundlich and BET isotherm models. It was found that the adsorption data followed the Langmuir isotherm model with correlation coefficients (R²) ranging between 0.9866-0.9997 and the adsorption capacities were between 11.99-22.94 mg/g.

Abstract: Riceberry brown rice is regarded as a source of various nutrients; often richer than white rice. Non-thermal plasma has recently been gaining a role for improving properties of cereal grains, especially brown rice. A number of methods of plasma treatment has been proposed including discharges as capacitive coupled plasma (CCP) and inductive coupled plasma (ICP). ICP has two operation modes as capacitive (E-mode) and inductive (H-mode) discharge with rather distinct characters. In this study we have focused on using ICP Ar/O₂ plasma in both E-and H mode for plasma treatment on riceberry brown rice. The input power for plasma generation were set to 50 and 250 W for E-and H-mode, respectively. Plasma in H-mode was having higher plasma density than that in E-mode, as observed in the optical emission spectrum. The surface morphology of riceberry brown rice before and after Ar/O₂ plasma treatment was evaluated using a scanning electron microscope without or with an energy dispersive spectroscopy (SEM and SEM/EDS). It has been found that the bran layer was richer in elemental compositions than the endosperm. The surface of rice sample was found to be etched and more porous after plasma treatment. The Ar/O₂ plasma in H-mode was observed to offer higher effect. The surface contact angle was found to decrease from 120.1^o ± 0.9^o in untreated samples to 79.3^o ± 0.6^o and 99.2^o ± 0.8^o in plasma treated samples on E-and H-mode, respectively.