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Nanocrystalline Fe(1?x)Cox, Fe, Fe80N120,Cu70Fe18Co12 mixtures have been prepared by mechanical alloying using a planetary ball mill under several milling conditions. Their structures and magnetic properties were investigated. Mechanical alloying is a non-balanced process for synthesis materials. The structural effects of mechanical alloying of powders were investigated by scanning X-ray diffraction analysis. In this report, we examine the applicability of eddy current techniques in-process for monitoring of powder density particle size and the time necessary to structure variation. An eddy current based monitoring system developed to measure metal powder density is expanded for monitoring metal powder diameter in metal compounds. Experimental sensor readings were gathered using four different metal powders with known particle sizes Fe(1?x)Cox, Fe, Fe80N120 and Cu70Fe18Co12. Analysis of the data showed that the sensor output was in relation with different parameter of powder (diameter, density and structure) that the sensitivity of the sensor differed with the type of metal powder. The merit of this technique is its reliance on a simple and inexpensive sensor probe.

In this article, different treatment baths for corrosion protection of 2030 aluminum alloy in addition to replacing the hexavalent chromium due to the European recommendation were employed. This work is divided into three steps of treatment: first, anodization using molybdate inhibitor without and with phosphoric acid and, then, pre-oxidation with sodium hydroxide. In the last step, we studied the influence of conversion coating with the combination of sodium molybdate and fluoride on the anodic layer formed on aluminum alloy 2030. In order to characterize the formed layers, we use microstructural characterization (SEM, AFM, and nano-indentation), which allows highlighting the surface condition as well as the morphological distribution, and electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy which shows that the anodization treatment of the aluminum alloy with phosphoric acid and sodium molybdate offered better corrosion resistance. This resistance increased with the use of pre-oxidation and then reached a maximum value of 99.8% efficiency with the addition of the molybdate conversion coating which causes an increase in the double layer and gave an alternative possibility of chromium VI.

Efficient hydraulics program of oil and gas wells has a crucial role for the optimization of drilling process. In the present paper, a numerical study of power-law fluid flow through concentric (E = 0.0) and eccentric annulus (E = 0.3, E = 0.6 and E = 0.9) was performed for both laminar and turbulent flow regimes utilizing a finite volume method. The effects of inner pipe rotation, flow behavior index and diameter ratio on the pressure drop were studied; furthermore, the appearance and development of secondary flow as well as its impact on the pressure drop gradient were evaluated. Results indicated that the increment of the inner pipe rotation from 0 to 400 rpm is found to decrease pressure drop gradient for laminar flow in concentric annulus while a negligible effect is observed for turbulent flow. The beginning of secondary flow formation in the wide region part of the eccentric annulus (E = 0.6) induces an increase of 9% and a slight increase in pressure drop gradient for laminar and turbulent flow, respectively. On the other hand, the variation of the flow behavior index and diameter ratio from low to high values caused a dramatic increase in the pressure drop. Streamlines in the annulus showed that the secondary flow is mainly induced by eccentricity of the inner pipe where both high values of diameter ratio and low values of flow behavior index tend to prevent the secondary flow to appear. Keywords Computational fluid dynamics (CFD) • Power-law fluid • Pressure drop • Secondary flow List of symbols D o Diameter of the outer cylinder (m) D i Diameter of the inner cylinder (m) D h Hydraulic diameter (m) L h Length of the hydrodynamic entry (m) E Eccentricity of the inner cylinder (−) κ Diameter ratio (−) K Flow consistency index (Pa s n) n Flow behavior index (−) u Bulk flow velocity (m/s) Re Reynolds number Fluid density (kg/m 3) Shear rate (s −1)

Nanocrystalline Fe-35 wt%Ni-20 wt%Co has been prepared by using a high-energy planetary ball mill with increasing milling time from 4 to 36 h. Microstructural characterisations showed the development of an face-centred cubic nanostructured Fe-35 wt%Ni-20 wt%Co alloy with an average crystallite size of 8 nm. The magnetic investigation revealed that the nanostructures obtained from a milling time of 36 h have the highest magnetic saturation and the lowest coercive field. In addition, the hardness and the electromagnetic absorption of the Fe-35 wt%Ni-20 wt%Co alloy were found to increase with the milling time. These evolutions could be attributed to the crystallite size and the strain variations in the samples during milling.

In this paper, the structure and magnetic properties of nanocrystalline Fe (1-x) Co x mixtures are investigated. These structures are prepared using mechanical alloying based on planetary ball mill under several milling conditions. The structural effects of mechanical alloying of powders were investigated by scanning electron microscopy, X-ray diffraction analysis and bench of microwaves. Consequently, alloy powder with an average grain size of 10-13 nm was obtained. Maximum saturation magnetisation Ms was obtained at a composition value of 65% Co. Microwave measurements were performed on the mechanically milled Fe (1-x) Co x powder.

Solid solutions of Cu,O alone and Cu,O with ZnO or Cr,O, in ZnO . Cr,O, as well as solid solutions of ZnO in Cu20 . CrzO, have activities and selectivities for methanol synthesis comparable to solid solutions of Cu20 in ZnO. Addition of a secondary phase to these solid solutions limits the grain growth and produces higher surface areas.