Corrosion of Steel: Equilibrium & Rate Drop

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Discussion Overview

The discussion revolves around the corrosion of steel when placed in still water, specifically addressing why the corrosion rate decreases over time and whether this is related to the system reaching equilibrium.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant questions why the corrosion rate of steel in still water drops over time, suggesting it may be due to the system reaching some form of equilibrium.
  • Another participant proposes that the layer of corrosion, or rust, forms a protective barrier that slows down further corrosion, particularly noting that corrosion rates are higher in moving water where this protective layer is removed.
  • A later reply agrees with the idea that the oxide layer around the steel reduces the corrosion rate and relates this concept to the process of anodizing aluminum, mentioning additional properties of aluminum oxide.

Areas of Agreement / Disagreement

Participants generally agree on the notion that the protective oxide layer slows down corrosion, but the initial question regarding equilibrium remains open and is not explicitly resolved.

Contextual Notes

The discussion does not clarify the specific mechanisms behind the protective layer's effectiveness or the conditions under which equilibrium might be reached, leaving these aspects unresolved.

supasupa
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Say is a piece of steel is placed in still water and is corroding. Why will the corrosion rate drop away after time??

Is it because the system reaches some sort of equlibrium??
 
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thats ment to say : "Say if a piece of steel..." NOT " Say is a piece..."
 
I believe the layer of corrosion protects it. Corrosion rates are higher in moving water because the corrosion covering is always being washed away.
 
that makes sense... what you are saying is the oxide around the steel (rust) slows down the corossion rate
 
supasupa said:
that makes sense... what you are saying is the oxide around the steel (rust) slows down the corossion rate
That is correct. This is the theory behind anodising aluminium (although aluminum oxide also exhibits excellent thermal insulation properties)
 

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