Advanced Materials Research Vol. 925

Abstract: There are several techniques to deposit the metal oxide thin film such as electron beam evaporator, pulse laser deposition and reactive magnetron sputtering deposition. In this experiment, magnetron sputtering deposition techniques will be used to produce a copper oxide thin film due to its simplicity and repeatability performance. Recently, copper oxide thin film has been studied because of its low cost material, sensitivity to ambient condition and easiness to produce oxide thin film. It is one of the p-type semiconductor oxides materials that are suitable to be used as a gas sensing material. In order to increase the sensitivity and to optimize the properties of copper oxide thin film, it is essential to study on the plasma properties during the deposition of copper oxide. In current studies, Langmuir probe was used to investigate the effect of substrate bias towards the fabrication of copper oxide thin film at rf dissipation power of 400 W. The oxygen flow rate was fixed at 8sccm. The Langmuir probe tip was focus at roughly 2 cm above the substrate holder. The ion and electron current were collected from the plasma environment. Then the electron temperature, electron density, ion density, ion flux, Debye length and plasma potential at various substrate biases were evaluated from the current-voltage curve. The electron temperature at various oxygen flow rates was almost unchanged. The effect of substrate bias toward the electron temperature was also almost unseen, except that the electron temperature at-40 V bias voltage was slightly lower than others. In addition, the ion flux at the same plasma condition shows that the ion flux was higher at-40 V substrate bias voltage. The results suggest that the ion bombardment effect toward the deposited copper oxide thin film would be higher at low oxygen flow rate. Thus it will create a rough surface morphology or nanostructured copper oxide thin film. This is a potential ways to improve the sensitivity of copper oxide gas sensor.

Abstract: This study investigated co-cultivation of Tetraselmis suecica microalgae with Oil Palm empty fruit bunch (OPEFB) for anaerobic biomethane production and Palm oil mill effluent (POME) treatment. The highest specific biogas production (0.1162 m³ kg^-1 COD day^-1) and biomethane yield (3900.8 mL CH₄ L^-1 POME day^-1) was achieved with microalgae at 2 mL mL^-1 POME, and OPEFB at 0.12 g mL^-1 POME. Without co-digestion of microalgae, higher specific biogas production (0.1269 m³ kg^-1 COD day^-1) but lower biomethane yield (3641.8 mL CH₄ L^-1 POME day^-1) were observed. Second order polynomial model fits the data well with less than 5% error. Higher removal efficiency (62-95%) of COD, BOD, TOC and TN were achieved by aerobic and anaerobic treatment of POME with microalgae than without microalgal treatment after 3 and 7 days of hydraulic retention time (HRT).

Abstract: Titania (TiO₂) as a semiconductor has been intensively studied during the last decades. Regardless of its superior photocatalytic performance and extensive environmental applications, it has a wide bandgap which lead to a photocatalytic activity only in ultraviolet (UV) irradiation. To shift the activity of TiO₂ to visible region, a series of monometallic and bimetallic doped TiO₂ was prepared with 10wt% total metals loading. The photocatalysts were synthesized by sol-gel associated via hydrothermal method. The properties of the photocatalysts such as crystal size, surface morphology, total surface area, chemical state of the elements, and bandgap were investigated by using thermogravimetric analysis (TGA), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and BrunauerEmmettTeller (BET) measurement. XRD analysis showed that all samples displayed anatase (101) as a main phase of TiO₂ with average crystal size between 10-16 nm in a good agreement with the TEM results. The FESEM images show spherical particles less than 20 nm in size. The BET results indicated that all samples are mesoporous. The band gap of Ni-Cu/TiO₂ is reduced to 2.65 eV with more absorbance in the visible region compared to those of cu/TiO₂ and Ni/TiO₂.

Abstract: High strength aluminum alloys Al-Zn-Mg-Cu-(0.1) Ni produced by semi-direct chill casting process were homogenized at different conditions then conducted heat treatment process which comprised pre-aging at 120°C for 24 h, retrogression at 180°C for 30 min, and then re-aging at 120°C for 24 h. Microstructural studies showed that add Ni (0.1 wt %) to the alloy will be forming Ni-rich phases such as AlCuNi, AlNi, AlNiFe and AlMgNi which provide a dispersive strengthening affected in the solid-solution and the subsequent heat treatments. The results showed that by this three-step process of heat treatments, the mechanical properties of aluminum alloys Al-Zn-Mg-Cu-(0.1) Ni were substantially improved. The highest attain for the ultimate tensile strength and Vickers hardness for the alloy sample after applied the retrogression and reaging process is about 545 MPa and 237 HV respectively.

Abstract: In this study the evolution of the retrogression and reaging (RRA) heat treatment process on microstructure and mechanical properties of AA 7075 Al-alloys which produced by semi-direct chill (DC) casting process were investigated. Al-Zn-Mg-Cu alloys were homogenized at different heat treatment conditions, aged at 120°C for 24 h (T6), and retrogressed at 180°C for 30 min then re-aged at 120°C for 24 h (RRA). The results showed that this three-step process of the heat treatments, the mechanical properties of alloys was substantially improved. The highest ultimate tensile strength and Vickers hardness attained for the retrogression and re-aging about 530 MPa and 223 HV respectively. The precipitation strengthening is responsible about improve the strength under impact the retrogression and re-aging process.

Abstract: Nanocrystalline cadmium sulfide (CdS) thin films have been successfully grown onto glass substrate via chemical bath deposition (CBD) technique under microwave irradiation (MWI) as a heating source. Aqueous solutions of cadmium chloride (CdCl₂) and thiourea [SC(NH₂)₂] were used as Cd⁺ and S^- ion sources respectively. In this study, the effect of reactants molar concentration on the deposited thin films thickness and quality were investigated. Higher thickness was obtained for the film prepared with concentration of 10mM whereas; the lowest was for the film prepared using 11mM. Keywords: CdS, nanocrystalline thin films, molar concentration, properties.

Abstract: Deformation and energy absorption characteristic of biomass foam composites are important in crashwortyness efficiency. The type of foam that had been used in this research is polyurethane (PU) foam with plant-based filler which are turmeric powder (Curcuma Longa), charcoal powder, henna powder ( Lawsonia inermis) and lemon grass powder (Cymbopogon) that give natural color to the composites. The percentages of filler was specified to 10% by weight. PU foam was prepared by reaction of natural oil polyol and isocyanate with a ratio of 1 to 1.1 by weight. The mixture was stirred with 1500 rpm and was poured into the mould when mixture starting to expand. Band saw was used to cut the sample with desired dimension. The characterization of filler was done using Fourier Transform Infrared Spectroscopy (FTIR). Compression was tested using Ultimate Testing Machine (UTM) and scale to weigh the sample. Composites with henna filler have ductile like behavior that proved in stress-strain curved that show the rough line in the graph. Other composites have rigid like behavior which have a smooth line in a stress - strain curve.

Abstract: Cu doped TiO₂ at different metal loading was successfully prepared and investigated. Characterization of the prepared photocatalysts was carried out using X-ray diffraction (XRD), diffuse reflectance UVVis spectroscopy (DRUVVis) and scanning electron microscopy (SEM). Photodegradation study of aqueous diisopropanolamine solution (1000 ppm) using the prepared photocatalyst showed significant COD removal under visible light irradiation. The photocatalyst with 1.5 wt% Cu gave the highest COD removal of 45 %.

Abstract: Titanium dioxide (TiO₂) thin films based interdigitated electrodes (IDEs) have been synthesized using sol-gel method with hydrochloric acid (HCl) as catalyst. The prepared TiO₂ solution has been deposited onto silicon dioxide (SiO₂) substrates via spin-coating technique. Film was annealed at 500 °C and aluminium (Al) IDEs have been fabricated. Finally the X-ray diffraction (XRD) shows high intensity of both anatase and rutile peaks exist on 10 nm TiO₂ thin film. Average crystallite size of the nanoparticles is seen to be 25 nm. UvVisible spectroscopic (UvVis) technique was used for the transmittance spectra characterization of the sample.

Abstract: This research is concerned with one of applications of partially graphitized process of carbon compounds. The target of the work is to investigate and study the activity of some additives as catalysts to promote graphitization of phenolic resins to use in preparing thermally stable nanoparticles fillers. Two types of additives have been dedicated as promoting factors. Ni (CH₂COCH₂COCH₃)₂.2NH₃ is laboratory prepared. As for H₃BO₃, additive, it has been used ready-made. Two types of the modified resins are prepared through a chemical reaction and physical mixing between the resins and the inorganic compounds. Graphitization has successfully been conducted by implementing thermal treatment in a vacuum furnace at (1200-1400°C). This study exhibited the following results: FT-IR for modified resins showed the combination of boron-oxygen is attributed to the existence of the boron ion with the H₃BO₃, and the presence of ammonia molecules bonded to nickel ion in Ni (CH₂COCH₂COCH₃)₂.2NH₃ allow for hydrogen bonding, confirmed by very broad stretching vibration (OH). On the other hand, the action of these catalysts is referred to their contribution in accelerating the graphitization process and to decrease the operational temperature to 1400°C as compared to that needed by amorphous carbon in order to be changed to graphite via traditional process about 3000°C. X-ray analysis showed the existence of graphite and turbostratic structures of the type (T&G-comp.), This means the degree of graphitization (D.O.G) and carbon yield of the prepared resins by chemical reaction is more than that produced by physical mixing. H₃BO₃ had slight effect on the carbons and less than from Ni (CH₂COCH₂COCH₃)₂.2NH₃. Thermal analysis results (T, T.G, and T.G.A) of the modified resins should indicate that this property depends upon the type of the additive. Accordingly, it is possible to use these results in preparing modified resins and thermally stable fillers which can be used with composites. This requires investigating tests and experiments in this field. Key words: Catalytic graphitization, Degree of graphitization, Modified phenolic resins, Organometallic compounds, nanoparticles fillers.