In this work, the effect of heat input on the mechanical properties of low-carbon steel was studied using two welding processes: Oxy-Acetylene Welding (OAW) and Shielded Metal Arc Welding (SMAW). Two different edge preparations on a specific size, 10-mm thick low-carbon steel, with the following welding parameters: dual welding voltage of 100 V and 220 V, various welding currents at 100, 120, and 150 Amperes and different mild steel electrode gauges of 10 and 12 were investigated. The tensile strength, hardness and impact strength of the welded joint were carried out and it was discovered that the tensile strength and hardness reduce with the increase in heat input into the weld. However, the impact strength of the weldment increases with the increase in heat input. Besides it was also discovered that V-grooved edge preparation has better mechanical properties as compared with straight edge preparation under the same conditions. Microstructural examinations conducted revealed that the cooling rate in different media has significant effect on the microstructure of the weldment. Pearlite and ferrite were observed in the microstructure, but the proportion of ferrite to pearlite varied under different conditions.

Natural fiber reinforced composites have gained considerable attention particularly in the manufacturing industry owing to their light weight, corrosion resistance, abundance, and biodegradability. In this work, alkaline treated and untreated groundnut shell powder (GSP) was used to reinforce recycled polyethylene to produce GSP-recycled polyethylene composites with improved mechanical properties and biodegradability. GSP with particle sizes of 0 -300 µm and 300 -600 µm was used in different proportions: 5%, 10%, 15%, 20%, 25%, and 30% wt. The fiber was immersed for 5 hours in a 10 wt% NaOH solution. Tensile and hardness test data showed an improvement in mechanical properties of the treated fiber composites. Results of water absorption test also showed that treated GSP-recycled polyethylene composites had a lower rate of water absorption than the untreated GSP-recycled polyethylene composites. Through Fourier transform infrared spectroscopy, disappearance of characteristics peaks of hemicellulose and lignin was observed. Growth of fungi on the fiber-reinforced composites was observed, which was evidence that GSP-recycled polyethylene composite was biodegradable. Finally, SEM micrographs showed uniform distribution of treated fibers in the polymer matrix; this explained the observed improvement in the mechanical properties of treated GSP-recycled polyethylene composites.

An alumina-based nanocomposite is fabricated through the addition of secondary nanophase material to an alumina matrix to alter and tailor the properties of alumina. The addition to alumina of semi-conductive materials, such as silicon carbide (SiC), and high conductive materials, such as carbon nanotubes with a characteristic size in the nanometer range, can alter the mechanical strength, hardness, toughness, and electrical and thermal properties of alumina. This paper discusses recent advances in the synthesis of alumina–SiC and alumina-carbon nanotube (CNT) nanopowders and their consolidation using conventional and non-conventional techniques. Mechanical (hardness, fracture toughness and flexural strength) and functional (thermal and electrical) properties are discussed. The influence of the microstructure on the properties of alumina–SiC and alumina–CNT nanocomposites is discussed. Furthermore, potential applications and current related research trends are described.

Natural fibers are becoming the right candidate material as a substitute for glass fibers in the reinforcement of plastic polymers for various applications. The ease of their processing with minimal energy consumption and the quest to produce biodegradable plastics with lightweight has given natural fibers comparative advantages over synthetic fibers. In this study, groundnut shell powder (GSP) in different forms (untreated, sodium hydroxide treated and ash) were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray fluorescence (XRF), Nuclear magnetic resonance (NMR), Differential scanning calorimetry (DSC) and Scanning electron microscopy (SEM) to evaluate their possible utilization as reinforcement in polymers. GSP was treated with sodium hydroxide for 5 hrs and dried in vacuum for 24 hrs to obtain treated GSP while ash GSP was formed by heating GSP in the furnace at 600 °C for about 3 hrs. The results reveal that sodium hydroxide treatment was very effective in the breaking down of the hydrogen bond with a consequent reduction in the hydrophilicity of the GSP. This would promote GSP bonding with the hydrophobic polymer matrix in the development of natural fiber reinforced plastic polymer composite materials. Ash GSP was found to have the highest crystallinity among the three forms of GSP based on XRD results. Therefore, the result achieved in this work confirmed that treated and ash GSP fibers are good reinforcement material in the production of polymer composites, with the actual choice depending on end-use property requirements of the composite.