Effect of processing parameters on the mechano-chemical synthesis of nano crystalline Mo-Cu/Al2O3 composite

In this study, molybdenum-copper/alumina nano composite was synthesized with mechano-chemical method using high energy planetary ball milling. The molybdenum oxide, copper oxide and aluminum powder were used as starting materials and reaction appeared to occur through a rapid combustion reaction process. The evaluation of powder particles after different milling times was studied by X-ray diffraction (XRD), differential thermal analysis/thermogravimetric (DTA/TG) and scanning electron microscopy (SEM). XRD results show that with increasing milling time at ambient temperature the peak intensities of powders decreases and significant peak broadening due to decrease in the size of crystallites observed. As a result, after 100 h milling time a molybdenum-copper/alumina metal matrix nanocomposite was formed which matrix had a crystallite size of about 42  nm for cu, calculated from Williamson-Hall equation. In fact by increasing the milling time after reduction of metal oxides, molybdenum dissolves in copper matrix and supersaturated Cu(Mo) solid solution with a homogenous distribution of nano-sized Al2O3 as reinforcement materials was formed. The thermal analysis curves of 10 minutes milled sample shows some peaks related to reduction of copper and molybdenum oxide with aluminum. In addition the small endothermic peak at 650 °C observed from DTA curve is due to the melting of remaining Al

Effect of lateral laser-cladding process on the corrosion performance of Inconel 625

This study aimed to evaluate the corrosion properties of different samples coated by the laser-cladding method to find the optimal laser parameters. Thereby, potentiodynamic polarization (Tafel) and electrochemical impedance tests were performed to assess the corrosion resistance of coated samples. Consequently, the corrosion morphology of tested samples was inspected by scanning electron microscopy. The results demonstrated that the laser power directly correlates with pitting corrosion and defects on the surface of the samples. Moreover, when molybdenum and chromium ions are increased in the electrolyte solution, the passive and protective layers are more durable, as the ions are sited within the holes and defects, reducing the surface corrosion rate.Peer ReviewedPostprint (published version

The effect of sintering temperature on Cu-CNTs nano composites properties produced by PM method

In this research work, copper and CNTs have been processed using high energy milling in different milling times (5, 10 and 15 hours). FESEM and XRD have been used to characterize the milled powders. The FESEM micrographs of the milled powders indicated that the morphology of powders changed from spherical shape to flake as milling time increased. The effect of sintering temperature as well as CNTs content on the properties of Cu-CNTs nanocomposite has been investigated. The optimum sintering temperature to produce Cu-CNTs nanocomposites is determined to be 900 oC. The microstructure and phase analysis of Cu-CNTs nanocomposites were studied by field emission scanning electron microscopy and X-ray diffraction. Mechanical properties of nanocomposite samples at various sintering temperatures were investigated. Cu-CNTs nanocomposite with 4 vol.% CNTs fabricated by powder metallurgy method indicated the highest value of the micro-hardness and bending strength as compared to pure copper

Bactericidal properties of copper-Tin nanoparticles on Escherichia coli in a liquid environment

In this research, copper-tin alloy nanoparticles were made by a mechanical alloying method and were examined by two well-known and common bactericidal tests, optical density, and colony-forming units count in terms of bactericidal properties. To confirm the results, two different percentages were used as Sn-50Cu and Sn-83Cu, and standard amounts of these alloys were added to the Escherichia coli bacterial culture medium. The results of optical density show that with the addition of more values to the culture medium for bacteria, witnessing the destruction of bacteria, and also the results of colony counting tests can be seen that the number of colonies has decreased over time, even close to zero, which means the environment is free of bacteria. These standard values were different for both alloys; for the Sn-50Cu alloy, the maximum value was 4.5 mg, and for the Sn-83Cu alloy, it was 2.75 mg, which did not make any difference with the addition of these nanoparticles to the bacterial culture mediumPeer ReviewedPostprint (published version

Effect of Mn addition on Fe-rich intermetallics morphology and dry sliding wear investigation of hypereutectic Al-17.5%Si alloys

The effect of Manganese addition on the iron-rich intermetallics and wear behavior of Al-17.5%Si hypereutectic alloys has been studied. Dry sliding wear tests have been conducted using a pin-on-disk machine under different normal loads of 18, 51, 74 and 100 N and at a constant sliding speed of 0.3 m/s. The addition of 1.2 wt.% Fe to the base alloy increased the wear rate due to the formation of needle beta intermetallics. Introducing 0.6 wt.% Mn to the iron-rich alloy changed the beta intermetallics into the modified alpha phases, and therefore reduced the detrimental effect of iron. Mn addition up to 0.9 wt.% to the 1.8Fe alloy did not impede formation of needle-like intermetallic compounds and had no positive effect on the modification of microstructure

Evolution of mechanical properties, microstructure and texture and of various brass alloys processed by multi-directional forging

This study investigated mechanical properties and texture evolution of Cu-xZn alloys (x = 5, 15, 20, 30) processed by multi-directional forging (MDF) up to 6 passes at ambient temperature. Mechanical properties were examined via shear punch and hardness tests. Optical microscopy and high-resolution scanning electron microscopy (HR-SEM), equipped with electron backscattered diffraction (EBSD) detector were also utilized to characterize the detailed microstructures and texture evolutions. The MDFed Cu-xZn alloys after 6 passes showed superior mechanical properties without the reduction of electrical conductivity. Hardness, ultimate shear strength and shear yield strength of Cu-30Zn alloy improved by 213%, 83% and 85%, respectively after 6 passes of MDF. Enhancement of mechanical properties can be attributed to grain refinement. The MDFed Cu-5Zn alloy presented a predominantly Copper-type texture due to the higher activity of shear bands. By increasing Zn to Cu-15Zn and Cu-20Zn, Brass and Goss texture components were observed. Finally, Cu-30Zn alloy possessed a Brass texture which could be attributed to a higher amount of twinings