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Formation & Properties of Zn–Ca– Mn Tri – Cation’s Phosphate Coating on St37 Steels
, M.Sc. Thesis Sharif University of Technology ; Afshar, Abdollah (Supervisor) ; Ghorbani, Mohammad (Supervisor)
Abstract
Addition of heavy metal cations such as manganese and nickel in low zinc phosphating bath increases the corrosion resistance of coatings and provides more suitable substrates for painting (especially electrophoretic painting). In addition, due to accelerating property and low cost availability of heavy metal cations such as Mn, multi– cationic phosphating is cost effective. In the present study, chemical composition and operating parameters of zinc - calcium - manganese Tri- cationic phosphating solution were optimized. Then the effects of various parameters such as phosphating time, bath temperature and pH on properties of coating were investigated. According to the results, about 1 g/L was...
Low Temperature Metallic Foams
, M.Sc. Thesis Sharif University of Technology ; Askari, Masoud (Supervisor)
Abstract
Metal foams are considered as a group of new materials and are applied widely in various areas due to their particular properties such as low density, high strength-to-weight ratio and appropriate mechanical, thermal, physical, electrical and magnetic properties. The aim of the present study is acquiring the technical knowledge of Zinc foam production by melting route and also optimizing the effective parameters on the foam stability. For this reason, 4 Zinc foams were produced at different times and temperatures. The amount of Calcium as the melt fluidity reducing agent and Titanium hydride and Zinc carbonate as the blowing agent were the same in all the specimens. The effect of heat...
Oxygen and Rare Earth Doping Effects on REn 2BanCu2n 2Om Superconductor Compounds
, Ph.D. Dissertation Sharif University of Technology ; Akhavan, Mohammad (Supervisor)
Abstract
There are two challenging problems with the physical properties of the recently discovered cuprate, Y3Ba5Cu8O19 δ (Y358): (1) the value of its transition temperature (Tc) and (2) its unknown crystal structure. While some reports argue that Tc of Y358 and its crystal structure are completely different from those of the YBa2Cu3O7 δʹ (Y123) compound, other reports indicate the similarity of both transition temperatures and XRD patterns (or crystal structure) of these materials. It has been suggested that these similarities are due to oxygen deficiency (δ) of Y3Ba5Cu8O19 δ or the decomposition of Y358 to Y123. In this thesis, we address these issues. At first, we have tried to answer the...