No abstract

The recycling of copper coil into finished products via sand casting with subsequent cold extrusion was investigated. This paper examined the effects of cold extrusion on the mechanical properties of the scrapped copper coil using a locally manufactured extruder with a conventional face die. The mechanical properties tested on the extrudates are limited to hardness, tensile, and compressive strength. The results reveal that the hardness of extruded copper of 11.10 mm and 11.45 mm improved significantly by 39 % and 41 %, respectively, compared with respective non-extruded copper. The compressive and tensile strength increases by 42 % and 22 %, respectively, for 11.10 mm extruded copper compared with the corresponding non-extruded copper. Also, the elongation of the extruded copper of 11.10 mm and 11.45 mm increases by 33 % and 34 %, respectively. It was deduced that the extruded copper is more ductile than the non-extruded copper. The micrograph reveals that grains in non-extruded copper are relatively coarse and nonuniform with voids, but fine and relatively uniform grains are obtained in extruded copper. The grains are refined during cold extrusion, and voids and dislocations are reduced significantly.

Nanoparticles-modified paints have shown huge potentials in a broad range of functionalities like surface protection, antifouling, corrosion resistance, self-cleaning, slip resistance, abrasion resistance among others. Consequently, they have been deployed for several industrial applications including pipelines, buildings, automobiles, electronics, among others. To further enhance their functionalities, paint industries have expended huge resources on research and development of advanced paints that are compatible and appropriate for today's hostile environments. Studies have been conducted on the utilization of degradable biocides such as zinc oxide nanoparticles (ZnONPs), silver nanoparticles (AgNPs), copper nanoparticles (CuNPs), photocatalytic-active nano-titanium dioxide nanoparticles (TiO 2 NPs), and silica dioxide nanoparticles (SiO 2 NPs) as major additives in paints. These additives are designed to offer improved surface protection against microbial, physical, and chemical deteriorations as well as enhanced scratch resistance. However, the addition of nanoparticles to paints is not without its demerits. Nanoparticles can agglomerate within the paint matrix leading to poor surface protection. In addition, the health and safety concerns from human exposure to emissions of nanoparticles must be adequately addressed. A few reported studies on the toxicology of nanoparticles are either short-termed or having variant or inconclusive results. This paper reports a critical assessment of nanoparticles as additives in paints. Extensive characterization of nanoparticle-modified paints is reported while the implications on the environment are also explored. New directions, targeting enhanced functionalities and lower toxicity, are proposed.

The over-reliance on fossil fuels as a primary source of energy is partly responsible for the increase in carbon dioxide (CO2), depletion of the ozone layer, and general environmental pollution. In this study, torrefaction of Albizia zygia wood-calcium hydrogen phosphate (CaHPO4) catalyst blends was carried out in a tubular furnace to examine the impacts of temperature, time, and particle size on higher heating value (HHV) and energy yield (EY). Albizia zygia wood was obtained at an industrial sawmill junkyard nearby Kwara State University, dried, crushed, and sieved into 1 - 3 mm particle size. Optimal Combined Design (OCD) was employed for the design, modelling, and optimization of HHV and EY under the ranges of selected temperature (200 - 300?C), residence time (15 - 30 min), and particle size (1 - 3 mm) in an inert environment tubular furnace. The results of the analysis indicated that the temperature of 245?C, time of 22 min, and size of the particle 3 mm yielded a maximum HHV of 19.59 MJ/Kg and EY of 76.37% respectively. Also, the addition of catalyst (CaHPO4) at 10% reduced the ash content but enhanced the fixed carbon content of the biochar. The mathematical models for the HHV and EY for the torrefaction using the OCD imply an excellent fit with R2 of 0.92 and 0.96, respectively. The prediction accuracy indicates that OCD can be deployed for the accurate prediction of HHV and EY in torrified biomass.

Metal matrix composites (MMCs) are materials in which metals are reinforced with other materials preferably of lower cost to improve their properties. In this present study, Brass /Coconut Shell Ash powder (CSAp) composites having 0%, 5%, 10% and 15% weight CSAp were fabricated by stir-casting method. The tensile strength of the MMCs is in the order 15% > 10% >5% > 0% of CSAp. Hardness of the MMCs increases slightly with increase in the percentage body weight of CSAp, in the order 15% > 10% >5% > 0% of CSAp. The highest impact energy of 61 J was obtained for 5% CSAp. However, significant improvement in tensile strength and hardness values was noticeable at the 15%. Scanning Electron Microscopy (SEM) analysis of the MMCs shows dendritic structures formation, the reinforcing particles (CSAp) are visible and clearly delineated in the microstructure. Hence, this study has established that reinforcing brass matrix with coconut shell ash particles can result in the production of low cost brass composites with enhanced tensile strength, hardness and impact energy values.