A Comparative Electrochemical Study of AZ31 and AZ91 Magnesium Alloy

A comparative study has been carried out on AZ31 and AZ91 magnesium alloys in order to understand the electrochemical behavior in both alkaline and chloride containing solutions. The open circuit potential (OCP) was examined in 1 M NaOH and 3.5 mass % NaCl solutions. AZ31 magnesium alloy shows several potential drops throughout the immersion in 1 M NaOH solution, though AZ91 does not show this phenomenon. The specimens were anodized at a constant potential of 3 V for 30 minutes at 298 K in 1 M NaOH solution. The anticorrosion behavior of the anodized specimens was better than those of nonanodized specimens. The anodized AZ91 has better corrosion resistance compared to nonanodized specimen and anodized AZ31 magnesium alloy

Synthesis and Characterization of Cobalt Nanoparticles Using Hydrazine and Citric Acid

Cobalt nanoparticles were produced by employing the liquid-phase reduction method and hydrazine. The effect of citric acid additives on the formation and growth mechanism of cobalt nanoparticles was investigated using polarization methods. The cobalt nanoparticles produced in 0.2 M cobalt sulfate and 5 M hydrazine at 298 K had a spherical shape with a diameter of 400 nm. The dendritic nanoparticles formed with the decreasing of hydrazine concentration at 298 K. On the other hand, dendritic large particles are confirmed at 353 K. It was confirmed that the reduction reaction progressed with the addition of citric acid, and a hexagonal close-packed (εCo) phase was formed