Calcium Build Up and Corrosion

VooDoo

Hey Guys,

Just curiosity, but if a metal surface has a build up of calcium does this mean there is a higher chance of corrosion occurring? Or can it accelerate corrosion? Or is the build up on the surface of metal generally harmless?

Astronuc

Is this a heat transfer/heated surface?

Ca and Si (in aqueous systems) contribute to scale, and over time on a heated surface, they can reduce heat transfer coefficient and increase local temperature, which further drives corrosion.

Corrosion (conversion of metal to metal oxide) are driven by temperature and availability of oxygen at the metal/oxide interface.

VooDoo

Thanks for the reply. The piece of metal has just been exposed to the outside environment and is not in a aqeuous environment.

So would it be correct to say that the build up of calcium has no major negative effect on the metal besides maybe effecting its visual apprearance?

Whereas a shower head which is in a aqeous environment can be effected by calcium deposits due to the increased chance of corrosion?

Astronuc

So it's not in water, but outside, it is exposed to humidity, condensation, rain?

Well, depending on temperature swings and other corrosive species like Cl or NaCl, it could eventually shorten the service life, especially if it is load bearing.

Any scale may harbor moisture and other corrosive species, such as chlorides. Local deposits could lead to pitting and perhaps perforation of a metal sheet, depending on thickness.

Ca salt deposits or scale in a shower head usually degrades performance, and can clog the spray head, or cause leakage around bushings or moveable joints.