Preparation and Evaluation of Cu-Zn-GNSs Nanocomposite Manufactured by Powder Metallurgy

Room-temperature ball milling technique has been successfully employed to fabricate copper-zinc graphene nanocomposite by high-energy ball milling of elemental Cu, Zn, and graphene. Copper powder reinforced with 1-wt.% nanographene sheets were mechanically milled with 5, 10, 15, and 20 wt.% Zn powder. The ball-to-powder weight ratio was selected to be 10:1 with a 400-rpm milling speed. Hexane and methanol were used as a process control agent (PCA) during composite fabrication. The effect of PCA on the composite microstructure was studied. The obtained composites were compacted by a uniaxial press under 700 MPa. The compacted samples were sintered under a controlled atmosphere at 1023 K for 90 min. The microstructure, mechanical, and tribological properties of the prepared Cu-Zn GrNSs nanocomposites were studied. All results indicated that composites using hexane as PCA had a uniform microstructure with higher densities. The densities of sintered samples were decreased gradually by increasing the Zn percent. The obtained composite contained 10 wt.% Zn had a more homogeneous microstructure, low porosity, higher Vickers hardness, and compression strength, while the composite contained 15 wt.% Zn recorded the lowest wear rate. Both the electrical and thermal conductivities were decreased gradually by increasing the Zn content.

Green and Sustainable Technology: Efficient Strategy for Synthesis of Biologically Active Pyrimidine Derivatives

: Green chemistry is also referred as sustainable technology which involves the design, synthesis, processing and use of chemical substances by reducing or eliminating the chemical hazards. This strategy focuses on atom economy, use of safer solvents or chemicals, use of raw materials from renewable resources, consumption of energy and decomposition of the chemical substances to non-toxic material which are eco-friendly. So, this technology is utilized for the sustainable development of novel heterocyclic scaffold like pyrimidine derivatives. Pyrimidine is a six membered heterocyclic aromatic compound with two nitrogen atoms at positions 1 and 3 in the ring system. Among the other heterocyclic compounds, pyrimidine derivatives plays major role due to their diverse promising biological activities such as antimicrobial, antifungal, anti-viral, anti-tubercular, anti-diabetic, anti-hypertensive, anticancer, anthelmintic, antioxidant, anti-epileptic, antipsychotic, anti-anxiety, antimalarial, antihistaminic, anti-parkinsonian, analgesic and anti-inflammatory etc. The various green methods used for synthesis of pyrimidine derivatives include microwave assisted synthesis, ultrasound induced synthesis, ball milling technique, grinding technique, photo-catalysis. These processes enhance the rate of the reaction which leads to high selectivity with improved product yields as compared to the conventional synthetic methods. This review is focused on the green synthesis of biologically active pyrimidine derivatives.

Effect of nano-α-Al2O3 Particles on Mechanical Properties of Glass-Fibre Reinforced Epoxy Hybrid Composites

The present work deals with the mechanical properties of hybrid nanocomposites made of epoxy/glass fibre dispersed with different weight percentages of nano-α-Al2O3 powder . The nanoparticles were synthesized by a high energy ball milling technique (60 and 200 nm).. The effect of nano-α-Al2O3 size and content (wt%) on mechanical properties, such as tensile, flexural, interlaminar shear stress (ILSS) and hardness was investigated. The addition of nano-α-Al2O3 enhanced all measured mechanical parameters because of their higher surface area and interfacial polymer-metal interaction. The nanoparticle-embedded laminates showed an improvement in flexural strength and hardness compared to laminate without nano-α-Al2O3. Among all the wt% of varied sizes of nano-α-Al2O3, the highest tensile strength was shown by the addition of 0.5 wt% 200nm nano-α-Al2O3 (167.80 N/m2). The highest flexural strength (378.39 N/m2) Vickers hardness (86.72) were observed for laminates containing 1.5 wt% of 60nm nano-α-Al2O3, while the highest ILSS (31.21 Ksi) was observed for 0.5 wt% of 60nm nano-α-Al2O3. This study showed that there was a higher interaction between the nanoparticle and polymer resin, which led to increasing the mechanical properties of the laminate. This finding show that diversifiying the application of these hybrid materials was possible by adding nano-alumina.

Modifikasi Sifat Mineralogi dan Fisiko-Kimia Bahan Tanah Vertik dengan Ball Mill Berenergi Tinggi

test of modifying the properties of vertic material by using a ball milling technique was carried out with the primary aim to eliminate the vertic (swelling-shrinking) property and increase the electrical charge of the material. The clay fraction of Vertisol was dried and ball milled for 5, 10, and 20 minutes. Results reveal that the clay fraction of the soil material was dominated by montmorillonite mineral, and ball milling for > 5 minutes transformed the crystalline montmorillonite into amorphous (non-crystalline) particles. Those changes were followed by increasing the vertic features, cation exchange capacity, water holding capacity, and suspension effect of the milled material. The improvement of vertic characteristics might be due to the increase of electric charge of the milled particles. Thus, high-energy ball milling was an effective technique to improve the reactivity and vertic property of vertic material of Vertisols. Further studies are needed to evaluate the potential uses of modified vertic materials as ceramic material, cement component, adsorbent of heavy metals, and other contaminants, or catalysator

Enhancement of Electrical Conductivity of Aluminum-Based Nanocomposite Produced by Spark Plasma Sintering

This article focuses on exploring how the electrical conductivity and densification properties of metallic samples made from aluminum (Al) powders reinforced with 0.5 wt % concentration of multi-walled carbon nanotubes (MWCNTs) and consolidated through spark plasma sintering (SPS) process are affected by the carbon nanotubes dispersion and the Al particles morphology. Experimental characterization tests performed by scanning electron microscopy (SEM) and by energy dispersive spectroscopy (EDS) show that the MWCNTs were uniformly ball-milled and dispersed in the Al surface particles, and undesirable phases were not observed in X-ray diffraction measurements. Furthermore, high densification parts and an improvement of about 40% in the electrical conductivity values were confirmed via experimental tests performed on the produced sintered samples. These results elucidate that modifying the powder morphology using the ball-milling technique to bond carbon nanotubes into the Al surface particles aids the ability to obtain highly dense parts with increasing electrical conductivity properties.