15 What is the effect of the following parameters on the cor

15. What is the effect of the following parameters on the corrosion resistance of metals and why by increasing T(C) we may have reduction in corrosion rate?

-PH

-Grain Size

-Fluid Velocity

Solution

The pH of a solution is an important factor in the corrosion resistance of materials because hydrogen ions can interact and modify the surface and therefore alter the corrosion resistance of a material. Moreover, interactions between pH and dissolved species such as chloride ions can enhance the effect of hydrogen ions.

The corrosion resistance of pure magnesium is improved as the grain size decreases. The improvement in the corrosion resistance is attributed to refine grain can produce more uniform and density film on the surface of sample. But this depends on the type of material used, its purpose and the environment.

Corrosion rate increases at high fluid velocity and corrosion resistance decreases

An increase in temperature will generally cause an increase in the corrosion rate. A rule of thumb is that temperature increases of 10°C will double the corrosion rate. Thus decreases, the corrosion resistance.