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Thermal behaviour of three cells at Egyptalum smelter was investigated during baking and start-up stages by inserting twenty thermocouples in the sidewall carbon blocks and ten thermocouples in the bottom carbon blocks. The baking time, final average cathode surface temperature and the relative standard deviation for the anodic current distribution for these cells were about 71 h, 852 °C and 10 %, respectively. The heat-up rate during baking stage and the cell stability during the early operation period were improved. Temperatures in the sidewall carbon blocks at the end the baking stage in the range between 71 and 113°C and gradually increased after start-up stage to the temperatures in the range between 558 and 737 °C. The start-up time for these cells was 52 h. Valuable thermal relations were obtained between the sidewall carbon blocks and the steel shell during the baking and start-up stages. The results showed the sidewall carbon temperatures were unaffected by small voltage changes during the baking stage, but it affected by small voltage changes during the start-up stage. Voltage of cell 617 Voltage of cell 619 Voltage of cell 634 Current of cell 617 Current of cell 619 Current of cell 634 Cell current, kA

Metal matrix composite powders of Al-Al2O3 with weight fraction of 20 % Al2O3 could be synthesized by high-energy milling of the mixed powders. Three different experiments were carried out at the same operating conditions, but with three different rotation speeds; 200, 300, and 400rpm. A homogenous distribution of the Al2O3 reinforcement in the Al matrix was obtained after milling the mixed powders for periods of 60, 45, and 30 h. The homogenous distribution of Al2O3 in the Al matrix was achieved by characterizing these nanocomposite powders by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. X-ray patterns were analyzed by using the Williamson-Hall treatment to determine the crystallite size and the lattice strain.

The effect of joint addition of Zr, Ti and Cr on the grain refinement of commercial pure aluminium (99.7% Al) has been investigated by optical microscopy and scanning electron microscopy (SEM) as well as Energy Dispersive X-ray Spectroscopy (EDS). It was found that joint addition of 0.15 wt% Zr and 0.025 wt% Ti to Al can result in a remarkable refinement with an average grain size of 102 μm. It was found the optimum addition level of Ti to be 0.025 wt% in the presence of 0.1 % Zr and any increase in the Ti beyond 0.025wt% results in coarse grain size. Joint additions of 0.15 wt% Zr, 0.025 wt% Ti and 0.15 wt% Cr to Al facilitate better grain refinement and the average grain size was 75 μm. The grain refining performance of joint addition of 0.1 wt.% Zr and different additions of either Ti or Cr is higher than refining with zirconium alone. EDS and SEM analysis of the precipitated phases observed at or near the centers of the refined aluminium with joint addition of Zr and Ti was found to be Al3(Zr1-xTix). These Al3(Zr1-xTix) particles act as heterogeneous nucleation sites for α-Al during solidification and resulted in better grain refinement.

There is a well-based correlation between the pulsating amplitude σ A(R = 0) and the alternating amplitude σ A(R = – 1) in fatigue testing of sintered iron and steel which permits to predict the mean stress sensitivity and the pulsating amplitude if the alternating endurance limit σ A(R = – 1) has been measured. Without loss of precision the relationship can be extended from smooth unnotched specimen geometries to notched geometries if only the stress concentration factor is known. The coefficients of the predictive equation depend on the brittleness of the material, a systematic approach to take the brittleness into account is still missing. In Haigh diagrams, the slope of the σ A–σ m diagram with tensile mean stresses can be linearly extrapolated also into the compressive mean stress range σ m < 0.