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The formation mechanisms and characterization (distribution, size and morphology) of the inclusions during continuous casting process of steels were investigated in this study. Samples were took out from several steps of the process and then, fully characterized via metallographic techniques, microscopic investigations and elemental analysis. Results showed that the addition of ferroalloys can intensify the formation of inclusions in some steps of the steelmaking process. Also, it was confirmed that the total oxygen content of the samples can be considered as a criteria of the clarity (purity and inclusion-free) of the steels, if the samples prepared carefully.

The kinetic study for the synthesis of Fluorapatite has been done using the thermogravimetric technique under non-isothermal conditions and at four heating rates of 5, 10, 15 and 20 °C. Both model free and model-fitting methods were used to investigate kinetic parameters. Calcium oxide, phosphorus pentoxide and calcium fluoride were used as the precursor materials. The activation energy values were calculated through model-fitting and isoconversional methods and were used to predict the reaction model and pre-exponential factor. In this case several techniques were considered such as master plots and compensation effects. The results indicated that the reaction mechanism was chemically controlled with second and third order reaction models in the whole range of conversion which the activation energy varied from 25 to 43 kJ/mol.

In this work, Nono-crystalline aluminum carbide particles were synthesized using both mechanical and thermal treatments. Frist, Al and graphite powders had been milled in a planetary ball mill. Then, milled mixtures have been annealed isothermally after the mechanical activation. The effects of two processes on the synthesized products were separately studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and simultaneous thermal analysis (STA) methods. Further, the grain size, lattice strain and dislocation density values were calculated according to XRD data. The results showed that mechanical alloying process can create an ultra-fine microstructure. The grain size was mostly reduced after 40 h milling as well as the heat treatment at 550 °c and 2 h. in fact, the high rate of plastic deformation of aluminum particle during milling process lead to rising the internal energy of particles, and finally, nanocrystals of Al4C3formed with the size of 14 nm. However, thermal analysis indicated that the mechanical activation of aluminum and the presence of carbon can play key roles in synthesis of aluminum carbide. Key words: Mechanical alloying, annealing, Al and graphite powders, Solid state reaction, Nono-crystalline aluminum carbide.

In this study corrosion resistance of 316L stainless steel has been investigated in a solution containing different percentages of hypochloric solution. In order to examine the rate and mechanism of the occurrence of pitting corrosion in this steel, various corrosion tests have been used. In addition, the locale of the pitting corrosion has been examined by scanning electron microscope. Results show that the presence of chlorine ion with the increase of cathodic reaction rates cause to increase the likelihood of pitting corrosion in 316L steel.