This paper aimed to evaluate the polyurethane (pu) and polyurethane/polyvinyl chloride (90 wt.%/10 wt.%) as organic coating of carbon steel substrate against marine environment (3.5 wt.%) as a severe corrosion environment. The electrochemical impedance spectroscopy (EIS) and fitting impedance data by ZsimpWin 3.22 software were used to estimate the physical barrier of the samples for different exposure times. Different equivalent electrical circuits were taken for the physical barrier at different immersion times to get appropriate fitting. Both pu and pu/pvc coatings showed excellent corrosion protection for steel .The pu/pvc coating showed better protection and stability than pu coating against aggressive salt solution. The relation between dielectric properties (impedance spectrum) of coating film with their behavior as physical barrier protection gives useful information about electrochemical process and predicts the barrier protective behavior in natural environment.

The research was aimed at developing new reinforcement materials by using of different coating materials, included zinc, tin and lead. The experimental works included examination of coating defect, coating Adhesion study, and the adhesion between concrete and coated bars, and different techniques are employed to assess the performance of the reinforcement embedded in concrete at a saline environment of 3.5% NaCl solution. These include; Accelerated Corrosion Test ASTM G 109, Half Cell Potential Test ASTM C876, electrochemical polarization by Linear and Tafel polarization techniques, microstructure, and visual inspection. Some improvement to the ASTM G109 standard test method were suggested and led to get more useful results in a shorter period. The trend of the corrosion rate results of the all specimens (worst-to-best) can be arranged as follows: Galvanized CRS › untreated CRS› tin coated CRS › lead coated CRS › SST316

The effect of homogenous heating variables (temperature and time holding) on the tendency of high strength Al-alloys type 7020 is investigated. The experiments were carried out by heating the specimens at different temperatures (100, 150, 200, 250, 300, 350, 400, 450 and 500) °C for two periods of holding time (one hour and two hours). Microstructure of an alloy was investigated by the optical microscope before and after heating at each temperature and precipitation phase and clearing revealed MgZn 2 . An immersion test was applied on specimens after heating to show the reduction in weight. Polarization technique was used to study the effects of microstructures on their electrochemical behavior in 3.5% NaCl solution. Microscopic and X-ray examination were used to reveal pitting corrosion on the microstructure of non-heated and heated 7020 Al-alloys. The results show that increasing the temperatures of heating from 100°C to 500°C caused the appearance of pitting corrosion on the precipitated phases and increase of pitting corrosion tendency with increase of temperature of heating; increasing time holding of heating from 1 hr. to 2 hrs. increases the pitting corrosion.