Electrical charge developed by a snow plow?

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Discussion Overview

The discussion revolves around the potential causes of rust spots appearing on a truck equipped with a stainless steel snow plow. Participants explore various factors, including electrostatic charge, corrosion mechanisms, and the effects of de-icing materials used during snow removal.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether the snow and debris interacting with the stainless steel plow could generate a positive charge on the truck, potentially attracting negatively charged metal particles.
  • Another participant suggests that the use of a salt/sand spreader might be contributing to the rust issue, indicating a need for more information about the materials being used.
  • A participant mentions that calcium chloride and magnesium chloride are used after plowing, but residual materials from previous snowfalls could still be present on the concrete.
  • One participant proposes that the rusting could be due to galvanic corrosion, noting that dissimilar metals in contact can lead to corrosion, particularly when chlorides are involved.
  • Another participant challenges the idea of galvanic corrosion by suggesting that the stainless steel should be the one corroding, not the truck, and describes the rust as resembling iron filings rather than pitting corrosion.

Areas of Agreement / Disagreement

Participants express differing views on the cause of the rust spots, with some supporting the galvanic corrosion theory while others propose alternative explanations related to electrostatic charge and the nature of the rust itself. No consensus is reached on the primary cause of the issue.

Contextual Notes

Participants reference various corrosion mechanisms and materials, but the discussion lacks clarity on specific conditions and assumptions regarding the interaction between the snow plow, the truck, and the environmental factors involved.

tjwieseler
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I know this question seems to be a little out there, and I might not be in the right forum, but here it goes.

I have a friend that has a 2008 Ford F350 pickup with a stainless steel Fisher snow plow that has developed a problem with rust spots all over the truck. Rust is even showing up on plastic trim pieces. He previously had a painted steel blade on his truck and never had this problem.

Is it possible that when he is plowing the snow, the snow/dirt/sand/salt (whatever is in the snow) running across the stainless steel might give the truck a positive charge. Then the metal wear bar at the bottom of the blade is wearing off on the concrete and small metal pieces (with a - charge) are being attracted to the + charged truck?

Confused plow owner.
 
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Is your friend using a salt/sand spreader? It could be salt that is causing the problem but we need more information.
 
I know he does spread calcium chloride and possibly magnesium chloride, but this is spread after the plowing is done. I am sure that there is a residual left on the concrete from the last snow fall. I will ask him exactly what he is spreading.
 
Seems like old fashioned galvanic reaction called corrosion. The spots on the plastic maybe where solutions of salty water with iron have deposited.

Dissimilar metals in contact will cause the anode (dissolution) to corrode, and stainless steel and carbon steel are sufficiently dissimilar. Chlorides attack stainless steel, which might be a 304, which is one of the most common. If the stainless is more cathodic than carbon steel, the carbon steel may come under attack, and if there are cracks or porosity in the paint, that's where the underlying steel will be attacked.

Also - very importantly - "Large cathode develops current which falls on small anode, producing intense localized corrosion in the form of pitting." Significant pitting can lead to structural or functional failure.

Coatings technology handbook

Principles of corrosion engineering and corrosion control

Physical metallurgy
 
I understand what you are saying about the Galvanic Reaction, but wouldn't that mean that the stainless steel (which is 304) would be the surface that is being attacked, since it is a smaller size than the truck. The rust on the truck looks more like metal flakes deposited on the truck. You can scratch them off with your fingernail. If it was a pit in the paint, I would think you wouldn't be able to scratch off. It is like the truck is attracting the iron filings from the wear bar on the snow plow.
 

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