FOUNDING RESEARCH JOURNAL
Year:2020 | Volume:4 | Issue:1|Papers Count:6

The in-situ Al-Mg2Si composites have attracted much attention in many important industries such as automotive and aerospace due to their low density, high specific strength, good wear resistance and thermal stability. In this research, solidification characteristics of in-situ Al20%Mg2Si composites has been investigated using cooling curve thermal analysis technique. For this purpose, the thermal analysis curves of this composite have been plotted at three different temperatures of 750, 800, 850℃ and the effect of superheat on the solidification parameters has been investigated. The results demonstrated that the superheat temperature affect the nucleation and growth of primary Mg2Si phase and the eutectic reaction. Increasing the heat temperature from 750 to 850℃ , increases the nucleation temperature of primary Mg2Si, solidification range and decreases the growth temperature of the binary eutectic reactions. The size and aspect ratio of Mg2Si reinforcement phase decreases by increasing the superheat. Therefore, the distribution of these phases will be improved and it will promote better mechanical properties in the composite.

In this study two Fe-Cr-Co base alloys with typical compositions Fe-28Cr-15Co-1 Si (alloy A) and Fe-32Cr-23Co-1 Si (alloy B) were prepared by casting technique and anisotropic permanent magnets were produced by applying some special heat treatments. Studies revealed that the magnetic properties of investigated alloys are very low in as-cast and in solution annealed conditions but are significantly enhanced by applying TMT. The presence of a sideband alongside the (110) reflection peak in X-ray diffraction pattern after TMT demonstrated that spinodal decomposition was occurred in this stage of heat treatment. During the step aging treatment, chemical compositions of the two spinodal phases (α 1 and α 2) are changed which results in an increase in Jsα 1-Jsα 2 and therefore, the coercivity is increased. Moreover this study revealed that magnetic properties obtained in Fe-28Cr15Co-1Si alloy was as Br = 0. 72 T, Hc = 60. 50 kA/m and (BH) max= 31. 19 kJ/m 3 and was higher than Fe-32Cr-23Co-1Si. Microstructural investigations showed that in the Fe-32Cr23Co-1Si alloy with a higher chromium percentage, the non-magnetic sigma phase was formed, leading to a decrease in the magnetic properties.

Developing of corrosion resistant coatings for corrosive atmospheres increased during their resistance against diffusion of destructive factors. In this paper, non-electrolytic process was used for formation of aluminium-zinc flake coating on cast iron. The surfaces of samples were coated with different weight percentage of glue, solvent and alloying powder. The samples were evaluated by adhesion test and scanning electron microscopy (SEM). Results represented that 40 wt. % of glue was the optimum condition and formed a proper adhesion between coat and substrate. The cast iron samples were sprayed during one, two and three times under optimum condition. Then samples were tested in salt spray bath at 35℃ and 60 to 240 hours. The results showed three times spraying was best condition in corrosion test.

In this research, aluminum slag produced from melting aluminum alloy AA 8011 in melting and holding reverberatory furnace was collected. After the crushing and sorting, and passing the slags from sieves, the slag was heated in gas fired silicon carbide crucible furnace to 750° C, 800° C, 850° C and 900° C respectively and mixed with one percent coverall flux No. 11, and then poured in mixing ladle with a 3 Cm hole in bottom of ladle this hole was placed to extract of molten metal and pour in preheated ingot molds. After adding 1% coverall flux No. 11, it was mixing with 100, 200, 250 and 300 RPM for 15 minutes. The provided molten aluminum, cast continuously in to the preheated ingot molds. The results show maximum efficiency of aluminum recycling in 850° C and 250 RPM. There is not chemical composition changes between primary and recycled aluminum ingots. Also SEM and EDS microscopy tests, shows different amount of metallic and nonmetallic inclusions content or other impurities in each recycling conditions which was lower in recycled ingot at 850° C and 250 RPM.

Casting simulation has been recognized as an efficient tool for analyzing mold filling behavior, solidification and cooling, and prediction of the position and type of internal defects. The main concern in the current study is to predict the occurrence of porosity defects with the current casting design of a conical part, and then presenting practical solutions to remove or reduce the defects. Niyama dimensionless criterion was used for precise quantification of micro-porosity. The results of the casting simulation with accordance to the current process parameters showed that the occurrence of shrinkage porosity defect took place considerably. In order to suggest a solution to decline the extent of porosity, the inclination of the part wall was utilized. The results indicated that with an increasing slope, the amount of porosity is successively reduced. Besides it was found that a slope in the order of 0. 5° on the external wall would lead to a remarkable reduction in the shrinkage porosity by inducing the directional solidification. The effect of various designs of the casting including the positioning of the casting inside the mold on the extent of porosity is discussed.

Demand side management (DSM) is a popular topic that has been widely discussed in the electricity industry in recent years. Industrial processes, such as steel production, have complex planning in general. In many industrialized countries, these plants regularly participate in DR programs. Electric arc furnaces (EAFs) in steel mills have been recognized as having high potential for DSM. The widely used method for modeling, optimizing and planning such plants in general is the Resource-Task Network (RTN). To solve the problem of achieving optimal solution, it is recommended to use a meta-heuristic algorithm. For the purpose of comparison, two genetic (GEN) and particle swarm Optimization (PSO) algorithms are used for this purpose. Case studies were performed to illustrate the impact of the proposed method on the daily planning of a steel plant. Overall, the results indicate that incorporating OLTC into the planning of a steel plant results in improvements in reducing its daily costs.