Advanced Materials Research Vol. 620

Abstract: Feasibility of using recycled-Aluminum (re-Al) as reinforcement particulates in Sn-0.7Cu is assessed by powder technology method, whereby re-Al particulates are produced from discarded aluminum beverage cans. This paper focuses on the intermetallic compound (IMC) formation study between the fabricated solder composite on Cu-substrate. Throughout this study, four different composition of Sn-0.7Cu/re-Al (0.0, 3.0, 3.5, 4.0 wt.%) were studied. X-ray diffraction (XRD) was used to analyze the IMCs phase formation between the interfaces. New IMC phase of Cu₉Al₄ was detected beside Cu₆Sn₅ and Cu₃Sn in the composite solder samples. However, Sn-0.7Cu/3.0re-Al showed least formation of brittle IMCs compared to the monolithic solder.

Abstract: This study describes the formation of silica nanocolloids for drug delivery system (DDS) via micelles formation approach. Micelles formed above critical micelle concentration (CMC) of the surfactant in aqueous solution. In this study, non-ionic Tween 80 was used as a surfactant and its effect on size and distribution of silica nanocolloids DDS was systematically studied. From transmission electron microscope (TEM) images, the size of silica increased from 30 nm to 50 nm with increasing amount of Tween 80 from 0.02 wt%, 0.0275wt%, 0.035wt% and 0.045 wt% respectively. Silica DDS with 0.0275wt% as optimum amount of Tween 80 encapsulated poor water soluble drug, Rifampicin has larger size (~53.8 nm) with better encapsulation efficiency compared to silica DDS encapsulated water soluble drug, Isoniazid (~39.9 nm). X-ray diffraction spectrum shows that silica DDS produced is in amorphous structure. Stability test of silica DDS encapsulated Rifampicin in 1M Sodium Chloride (NaCl) and 1% mouse serum are 42.78 % and 64.91%, respectively, which is inacceptable range for drug delivery application.

Abstract: Friction stir processing (FSP) is a material processing technique recognized to enhance the mechanical properties of the material owing to micro-structural refinement. In the present study, the feasibility of the use of FSP for processing of mild steel has been explored. Using FSP, the micro-structural refinement of the steel surface was obtained, resulting in an average grain sizes of the order of 100 nm as confirmed by atomic force microscopy (AFM). Along with grain size refinement, an evolution of various phases was also studied with the help of X-ray diffraction (XRD). It was observed that ferrite was the only phase present in both processed and unprocessed steel.FSP was found to be useful to enhance the micro-hardness of the steel by 50 to 80%, in comparison with that of the un-processed steel.

Abstract: Sodium titanate gels have been formed on the surface of titanium metal using sodium hydroxide solution and then oxidised at 400° - 800°C. The reaction sequence for these processes with increasing temperature is Ti sodium titanate gel crystalline sodium titanate gel porous (top) and dense (bottom) anatase porous (top) and dense (bottom) rutile. These samples were subsequently soaked in simulated body fluid in order to study the precipitation of hydroxyapatite.

Abstract: Cordierite (2MgO.2Al₂O₃.5SiO₂) is widely used in high temperature applications due to its high melting temperature and high resistance to thermal shock, chemical and corrosion. In this study, porous cordierite was synthesized using sol-gel method followed by replication of polymeric sponge method. Three different sintering temperatures were studied (1200°C, 1300°C and 1400°C to determine the crucial temperatures meant for pure cordierite phase. The effect of different temperature on the pore size, density and porosity were also studied. Produced porous cordierite was then analyzed using X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). XRD results showed that pure cordierite phase was obtained at 1300°C. SEM micrograph shows that with increasing sintering temperature, the pore size decreased and sample sintered at 1300°C has pore size ranging from 61-126μm.

Abstract: In this study, an efficient method to achieve a wide range of high-quality zinc oxide (ZnO) nanostructures through zinc powder evaporation at different temperatures is developed. ZnO nanostructures could be synthesized on n-type silicon substrates by a simple thermal evaporation technique without a catalyst at 600°C, 700°C, 800°C, and 900°C. Samples are annealed in wet oxygen and ambient argon gases. Surface morphology, crystallinity, and optical properties of the ZnO nanostructures are examined by scanning electron microscopy and transmission electron microscope measurements, X-ray diffraction, and photoluminescence measurement.

Abstract: The growth of thin oxide layer due to the variation in temperature on the surface of aluminized carbon steel was investigated. Hot dip aluminizing of low carbon steel was carried out at 750 °C in a molten pure aluminum for 5 minutes. Aluminized samples were heat treated at 600 °C, 700 °C, 800 °C, and 900 °C for 1 hour. The formation of aluminum oxide layer was investigated in this study. Optical microscopy, Atomic Force Microscopy (AFM), SEM and EDAX were used in investigation. From the observation, the appearance of aluminum oxide layer increased with the increase in temperature. The result of EDAX analysis revealed the existence alumina phase. Surface roughness measurement showed increment with the increase in oxidation heat treatment temperature.

Abstract: Due to environmental concerns, lead-free solders were introduced in replacing the lead-based solders in microelectronics devices technology. Although there are many lead-free solder available, the Sn-Ag-Cu is considered the best choice. But the solder has its draw backs in terms of melting temperature and intermetallic formations. To improve the solder, a fourth element Zn was added into the solder. The new composite solders were synthesized via powder metallurgy route. This research studies the effect of 0.1wt% Zn addition on the hardness and intermetallic formation on Cu substrate. For the hardness results, the micro Vickers values were reported. For intermetallic, the solders were melted at 250°C and aged at 150°C until 400 hours. The microhardness value for Zn based composites solder shows higher micro Vickers hardness compared to un-doped counterparts. The phases formed and its growth was studied under SEM and by energy dispensive x-ray (EDX). The SEM results show the presence of Cu₆Sn₅ and Cu₃Sn intermetallics and the Cu₅Zn₈ intermetallic was not detected. The addition of 0.1wt% Zn has retarded the growth of the Cu₃Sn intermetallic but not the total intermetallic thickness.

Abstract: Catalytic oxidation of oleic acid with ozone gas by using ozone-generator and solvent free medium in the presence of WO₃-Polypyrrole (ppy) nanocomposite was studied. Azelaic acid (AA) and pelargonic acids (PA) are the major reaction products, however the percentage of AA production is significantly higher than PA. Experimental results concluded that tungsten oxide and tungten oxide on polypyrrole are suitable catalysts in terms of their selectivity and activity. Reaction is done in two steps within 90 minute, showing the reasonable promotion in selectivity to AA by using WO₃-ppy catalyst system compared to reaction with WO₃ as catalyst. WO₃-ppy nanocomposite is prepared by sonication method and characterized by FT-IR, XRD, and FESEM analysis. The products of ozonolysis are identified by GC-FID and GC-MS for measuring selectivity and reactivity as well.

Abstract: Highly ordered TiO₂ nanotubes were successfully prepared via a facile anodization method in ethylene glycol and water mixture electrolyte (99 vol% EG + 5 wt% NH₄F). The as-anodized TiO₂ nanotubes were crystallized by annealing at 400 °C for 4 hours in argon atmosphere. A series of phosphorus incorporation with different phosphorus content have been prepared by soaking TiO₂ nanotubes samples in H₃PO₄. The photocatalytic activity of TiO₂ nanotubes and P-incorporated TiO₂ nanotubes were evaluated by the photodegradation of methyl orange. It was found that the photocatalytic activity of P-incorporated TiO₂ nanotubes was 34% higher than TiO₂ nanotubes.