حسین عبدوس

The thermodynamic and kinetic behavior of nickel aluminide IC221M alloy in molten eutectic of lithium/sodium carbonate was investigated. The nickel aluminide IC221M alloy was produced by vacuum arc re-melting (VAR) method. Surface layer products formed after immersion in molten carbonate at 600, 650 and 700 oC were examined by SEM and XRD. The results along with weight difference calculations showed that IC221M alloy doesn’t have a good resistance at 650 and 700 oC . It was evidenced that the destruction of the alloy is a diffusion-controlled process. The activation energy of the process was calculated to be 423 kJ/mol and the process kinetics were controlled by aluminum diffusion in γ´ phase.

Corrosion behavior of self-coated Nickel Aluminide IC221M alloys were examined in molten carbonate media with LiNaCO3 eutectic composition, to investigate the possibility of usage in wet-seal area in molten carbonate fuel cell. The desired temperature and time of oxidation process assigned as 1000֯ C and 25 hours respectively. Self-coating process resulted the formation of NiO NiAl2O4 ZrO2 and Al2O3 in order, from the outer interface. Under these compounds, in the substrate interface, an Aluminum depleted zone (ADZ) was observed. Oxide compounds together with this layer, perform as a barrier for alloying elements outward diffusion. After immersion test, more stable compounds such as NiCO3 LiAlO2 and CrO3, Na2CrO4 (formed by Cr diffusion), were observed above the ADZ. Weight-gain rate between the 100 to 215 hours of immersion test were estimated 2*10-5 g. cm-2. hrs-1 with a decreasing trend by time progress; which means that the mentioned stable compounds, provide a suitable corrosion resistance in Base alloy, after formation of required amount.

Fast changes at technologic، cultural and social level in community could cause many physical، psychological and social problems for some adolescents. The aim of this study was making clear the views of high school students of Semnan city on prevalent high risk behaviors and important family factors involved. This study is a qualitative research with content analysis. Through a purposivesampling، 98 students (boys & girls) at 3rd grade of highschools of Semnan city was selected and participated. Setting up 8 focus group discussion with some open questions as guide line، data gathering was carried out and at the same time analysis of data was started. Based on objectives of the study، coding of data was performed and themes were extracted. In the course of content analysis، 3 main and 4 subordinated themes were extracted. Main themes are: common high risk behaviors in this age group، parenthood approaches and psychological atmosphere in the family. Comprehensive and continuous education of adolescents and parents about common high risk behaviors isassociated with correct parenthood approaches، control، and providing guidance to adolescents that found useful for decreasing risky behaviors and modifying effective family factors.