Papers by Keyword: Cu

Abstract: The reuse of sludge in clay brick material is a long-term approach to sludge disposal for economic and environmental sustainability. In this study, steel mill sludge collected from Kluang, Johor was used to be investigated to replace clay as brick material. The raw material has been characterized using X Ray Fluorescent (XRF) analysis. The optimum moisture content (OMC) and maximum dry density (MDD) of the soil used was performed by using Standard Proctor Compaction Test in order to verify percentages of water used during brick manufacturing. Brick were manufactured into different percentages which are control brick (0%) and steel mill sludge brick with 5%, 10% and 15% of steel mill sludge waste. Manufactured brick was dried and fired in a furnace at 1050 °C. The results showed that zinc (Zn) and copper (Cu) are the higher heavy metal concentrations detected in steel mill sludge. Meanwhile, leachability test showed that heavy metals leached from steel mill sludge brick are low under permissible limit and complied with United States Environmental Protection Agency (USEPA).

Abstract: Aluminium is a light-weight material and possesses high corrosion resistance, so that it is widely used in manufacturing industries. The Al-Zn series have the highest strength compared to other aluminium alloys. To further increase the strength of Al-Zn alloys, Mg and Cu are added and age hardening treatment is applied. This research studied the precipitation process in Al-9Zn-4Mg (wt. %) alloys with Cu content of 0, 1, 3 and 5 wt.%. The alloys were produced through investment casting taking the shape of turbine impeller. The samples were solution treated at 460 °C for 2 hours and then aged at 130 °C. The characterization included hardness testing to observe response of age hardening, microstructural observation and Differential Scanning Calorimetry (DSC) testing. Microstructural observation was conducted by optical microscope and Scanning Electron Microscope (SEM) which was combined with Energy Dispersive Spectroscopy (EDS). The results showed that addition of Cu initially decreased the hardness during early ageing (2 hours) due to segregation of Cu-V complexes toward the grain boundaries which then decreased the hardness and enlarged the grain boundary phases. However, the peak hardness of the alloys was not affected by the increase in Cu content. due to high concentration of Zn and Mg. Exothermic reactions of formation of GP zones, η", η' and η (MgZn₂) were found during precipitation process while endothermic reaction were observed due to dissolution of the phases. Presence of MgZn₂ and Al₇Cu₂Fe second phases were observed in grain boundaries.

Abstract: Photoluminescence (PL), ultraviolet-visible (UV-VIS) absorption spectroscopy and spectroscopic ellipsometry (SE) are combining to study the optical transitions and electronic structures of Cu doped ZnO films with Cu concentration of 0, 2 and 8 at. %. By increasing Cu concentration, PL spectra show the enhancement of optical transition through the significantly increase of the green emission. Correspondingly, the in-plane UV visible absorption spectra show the redshift of first interband transition as the evidence of ZnO film become less insulating. More interestingly, extracted optical properties such as n and k clearly shows the mid-gap optical states, interband transitions and excitons. The excitonic peak decrease by increasing Cu concentration accompanied by a new broad structure assigned as a mid-gap state located under the conduction band area. Excitonic states are screened as decreasing its intensities by increasing Cu doping. Our results are beneficial to define interband transition and explain the mid-gap state in the oxide based semiconductor.

Abstract: The work analyses microstructures of ZnAl4Cu1, ZnAl27Cu2 and ZnAl40Cu2Si2 alloys in cast condition and after heat treatment in relation to microhardness HV_0.2 and purity of the alloys. As shown the microstructure of ZnAl4Cu1 alloy contained η phase and eutectoid, which consisted phases α + η. ZnAl27Cu2 alloy contained α phase, eutectoid and ε phase, and ZnAl40Cu2Si2 alloy had a similar composition, but moreover contained Si particles. Microhardness in the molten state in ZnAl4Cu1 alloy was HV_0.2 = 94, in ZnAl27Cu2 alloy it was HV_0.2 = 117, and in ZnAl40Cu2Si2 alloy it was HV_0.2 = 142_.

Abstract: This paper analyzed the content, distribution and source of Cu in Jiaozhou Bay in 1982. Results showed that the Cu contents in surface waters were relatively low, and the pollution level of Cu in 1982 was very slight. The major Cu source in the southwest of the bay was overland runoff; while for the northeast ocean current was responsible. The input contents of overland runoff and ocean current ranged from 2.22-3.56 μg.L^-1 and 0.15-5.31μg.L^-1, respectively.

Abstract: H-Sep samples were taken from treating sepiolite with HCl solution. Cu/H-Sep samples were prepared by the incipient wetness impregnation method. The samples were characterized using XRF, XRD, and XPS techniques, and their catalytic activities were performed by the SCR of NO with propylene. The results show that the Cu/H-Sep catalyst exhibited the high performance in the C₃H₆-SCR of NO. After investigation by XRD and H₂-TPR, the result showed that there are Cu²⁺/Cu⁺ redox species as a reaction activity center over Cu/H-Sep.

Abstract: Cu/Na-Sep samples were prepared by the incipient wetness impregnation method. These catalysts were characterized by means of XRF, XRD, and XPS techniques, and their catalytic activities were performed by the SCR of NO with propylene. The results show that the Cu/Na-Sep catalyst exhibited the high performance in the C₃H₆-SCR of NO. After investigation by XRD and XPS, the result showed that there are Cu²⁺/Cu⁺ redox species as a reaction activity center over Cu/Na-Sep.

Abstract: This work regards the three main soil types in local area of eastern China as the research objects, that is, cinnamon, fluvo-aquic and brown soils are conducted corresponding investigations. In order to analyze the effects which Cu and Zn exert on urease’s and catalase’s activity as well as the microbial biomass carbon, the exogenous Cu and Zn were added to the gathered surface soil with the depth of 0-20cm.

Abstract: Analysis on the concentrations of Pb, Cu in the roots, stems, leaves of phragmites australis which grows on Lingang New City of Shanghai showed that both of Pb, Cu in roots were higher concentrations than that in stems and leaves; the absorption of Pb,Cu had obvious seasonal variation; in winter, the enrichment of Pb, Cu in phranmites autralis was occurred and the enrichment ability of Pb was higher than Cu,

Abstract: It is important to specify the Cu diffusion path in the oxide layer of a Cu/oxide/Pt-structured conducting-bridge random access memory (CB-RAM), in terms of both the elucidation of resistive switching mechanism and optimization of memory performance. A first-principle calculation is effective in specifying the Cu diffusion path with atomic resolution. However, reported results of first-principle calculations are based on too simplified model to depict the actual system of CB-RAM. In this paper, a periodic slab model for the first-principle calculation of Cu diffusion process in HfO₂-CB-RAM was proposed based on experimental results. Both the most probable Cu diffusion surface and Cu diffusion path were suggested by the first-principles calculations based on the model. It was also suggested that the Cu diffusion path was modified by introducing oxygen vacancy into the Cu diffusion surface.