Research Articles
http://atuspace.atu.edu.gh:8080/handle/123456789/42
2024-03-29T00:14:31ZAn analytical model of diesel injector’s needle valve eccentric motion.
http://atuspace.atu.edu.gh:8080/handle/123456789/3098
An analytical model of diesel injector’s needle valve eccentric motion.
Wang, C.; Adams, M.; Jin, T.; Sun, Y.; Röll, A.; Luo, F.; Gavaises, M.
Past experimental studies have shown that the needle valve of high-pressure diesel injectors undergoes lateral movement and deformation, while the continuous increase in injection pressure enlarges the gap of the needle valve assembly. Two different analytical models, considering or omitting this change are presented here, linking the geometries of the needle valve assembly with the magnitude of needle valve tip lateral movement. It is found that the physical dimensions of the needle valve assembly and the injection pressure have a significant impact on the radial displacement of the needle. For example, for nominal clearances between the needle guidance and the needle valve of about 1–3 μm, the magnitude of the radial movement of the needle tip could reach tens of microns. The model that takes into account the variation of the gap between the needle guide and needle valve is found to give predictions closer to the experimental results.
2022-01-01T00:00:00ZCharacterization of Al-5Ni-0.5 Mg/x (Al2O3-GNs) nanocomposites manufactured via hot pressing technique.
http://atuspace.atu.edu.gh:8080/handle/123456789/3072
Characterization of Al-5Ni-0.5 Mg/x (Al2O3-GNs) nanocomposites manufactured via hot pressing technique.
Yehia, H. M.; Nyanor, P.; Daoush, W. M.
Exfoliating graphite to graphene nanosheets by mechanical ball milling with alumina, coating alumina particles with graphene layers to enhance their electrical and thermal properties, minimizing aluminum composite's production time, and improving the adhesion between the matrix and reinforcement were the aims of this study. Ball milling (BM) followed by electroless silver coating was used to prepare the (Al2O3-GNs) hybrid nanoparticles. A matrix sample from Al, 5 wt% Ni, and 0.5 wt% Mg was reinforced with different ratios of (Al2O3-GNs)/Ag nanoparticles up to 7.5 wt%. The cold and hot compaction technique was used to prepare the study samples. 550 °C and 50 min were the suitable parameters for fabricating the aluminum matrix composite. Microstructure investigation has been followed by chemical analysis, hardness, compressive strength, and electrical conductivity measurements. New intermetallic phases Al50Mg48Ni2, AlNi, and AlMg, have been formed during the powder consolidation by the hot-pressing process. The density of the Al-5Ni-0.5Mg (3.005 g/cm3) matrix was not significantly affected by the Al2O3/GN (3.907 g/cm3) reinforcement density. The 7.5 wt% Al2O3-GN reinforced composite exhibits the highest hardness. The electrical conductivity and the composites' compressive strength are also increased by 133% and 78%, respectively, for the 7.5 wt% sample.
2022-01-01T00:00:00ZSelf-Formed Diffusion Layer in Cu (Re) Alloy Film for Barrierless Copper
http://atuspace.atu.edu.gh:8080/handle/123456789/3071
Self-Formed Diffusion Layer in Cu (Re) Alloy Film for Barrierless Copper
Cheng, B.; Chen, H.; Asempah, I.; Wang, J.; Zhu, Y.; Wan, J.; Qiao, Y.
The barrier properties and diffusion behavior of Cu(Re) alloy films were studied. The films were deposited onto barrierless SiO2/Si by magnetron sputtering. X-ray diffraction patterns and electric resistivity results proved that the Cu(Re) alloy films without a barrier layer were thermally stable up to 550 °C. Transmission electron microscopy images and energy-dispersive spectrometry employing scanning transmission electron microscopy provided evidence for a self-formed Re-enriched diffusion layer between the Cu(Re) alloy and SiO2/Si substrate. Furthermore, the chemical states of Re atoms at the Cu(Re)/SiO2 interface were analyzed by X-ray photoemission spectroscopy. The self-formed diffusion layer was found to be composed of Re metal, ReO, ReO2 and ReO3. At 650 °C, the Cu(Re) layer was completely destroyed due to atom diffusion. The low electrical resistivity in combination with the high thermal stability suggests that the Cu(Re) alloy could be the ultimate Cu interconnect diffusion barrier.
2022-01-01T00:00:00ZHydrothermal fabrication of MoS2/reduced graphene oxide nanohybrid composite for the electrochemical sensing of Hg (II) in green tea.
http://atuspace.atu.edu.gh:8080/handle/123456789/3070
Hydrothermal fabrication of MoS2/reduced graphene oxide nanohybrid composite for the electrochemical sensing of Hg (II) in green tea.
Annavaram, V.; Somala, A. R.; Chen, Q.; Kutsanedzie, F. Y.; Agyekum, A. A.; Zareef, M.; Hassan, M. M.
Heavy metal contamination is a standout among the most genuine ecological issues: toxicity, persistence, bioaccumulation, and biomagnification through food chains. The present work aims at the synthesis of abundant, fast-sensing electrochemical sensors MoS2 and MoS2@rGO composite by the hydrothermal method to develop electrochemical sensors for the detection of Mercury (Hg-II). The synthesized material was characterized and conformed to a hierarchical spherical sponge-like structure with a high surface-to-volume ratio. The electrochemical sensor conditions were observed at ambient conditions to detect Hg (II) (0.5, 1, 1.5, 2, 2.5, 3, 3.5 µm L−1 was used) and the results showed very promisingly. The limit of detection (LOD) was found to be 2.0 × 10−7 µg/mL for MoS2, 1.22 × 10−8 µg/mL for composite. The heavy metals were spiked in green tea extract to observe the sensor ability of the material. The sensor ability for the material for real-time detection of green tea was found to be LOD-2.12 × 10−7 µg/mL (MoS2) and 1.21 × 10−9 µg/mL (MoS2@rGO).
2022-01-01T00:00:00Z