Rust on chrome

Discussion in 'Paint and Body' started by chromebumpers, Jul 5, 2018.

  1. chromebumpers

    chromebumpers solid fixture here in the forum Staff Member

    I’m confused. I always thought when the “pimples” start appearing on chrome there’s nothing that can be done to remove such rust as it has broken through the surface to the base metal.

    My past plating experience was using an abrasive wheel to remove any and all imperfections that may telegraph to the new plated surface. That action wears off the chrome, not what you want to leave as is.

    Some say to use Aluminum foil to remove rust, that most be a joke as all that did was to scratch the chrome.

    Anyone have before and after pictures of rust removed by whatever means?

    Rich
     
  2. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    Ahhh...Your The Chrome Plating Expert & Chemistry Expert Richard.
     
  3. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    0000 Steel wool maybe.
    Chrome Polish ?
     
  4. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    I Really like Evapo Rust Remover.
    Does pretty good with an old bath towel wrapped around your part.
    Pour Evapo Rust on the towel.
    Then wrap in a garbage bag.
    Place in the sunlight and wait.
     
  5. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    if you can physically feel the discoloration, it indicates iron oxidation through the nickle or copper under coated bonding base,of the chrome over lay
    it will need to be polished and re-nickle coated then re-chromed, to seal micro fissures, any abrasive will simply polish the surface visual indications out temporarily,
    but not remove the underlying cause , oxidation (rust) thus the problems symptoms may not be visible, but the potential damage and problem are still there.
    yes you can polish it out if its not too bad and use a high quality wax to seal the micro fissures but the problem will return if the wax is worn or eventually degrades.
    you might consider mounting several anodes bolted on the bumper in hidden areas behind and out of visual sight to reduce the damage

    yeah I know too many years spent as an engineer

    https://chem.libretexts.org/Textbook_Maps/General_Chemistry/Map:_A_Molecular_Approach_(Tro)/19:_Electrochemistry/19.9:_Corrosion:_Undesirable_Redox_Reactions


    http://garage.grumpysperformance.com/index.php?threads/anodes.74/#post-4127

    http://www.npl.co.uk/upload/pdf/bimetallic_20071105114556.pdf



    under ambient conditions, the oxidation of most metals is thermodynamically spontaneous, with the notable exception of gold and platinum. Hence it is actually somewhat surprising that any metals are useful at all in Earth’s moist, oxygen-rich atmosphere. Some metals, however, are resistant to corrosion for kinetic reasons. For example, aluminum in soft-drink cans and airplanes is protected by a thin coating of metal oxide that forms on the surface of the metal and acts as an impenetrable barrier that prevents further destruction. Aluminum cans also have a thin plastic layer to prevent reaction of the oxide with acid in the soft drink. Chromium, magnesium, and nickel also form protective oxide films. Stainless steels are remarkably resistant to corrosion because they usually contain a significant proportion of chromium, nickel, or both.

    In contrast to these metals, when iron corrodes, it forms a red-brown hydrated metal oxide (Fe2O3•xH2O), commonly known as rust, that does not provide a tight protective film (Figure 19.9.1" role="presentation" style="display: inline-table; line-height: normal; text-align: left; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">19.9.119.9.1). Instead, the rust continually flakes off to expose a fresh metal surface vulnerable to reaction with oxygen and water. Because both oxygen and water are required for rust to form, an iron nail immersed in deoxygenated water will not rust—even over a period of several weeks. Similarly, a nail immersed in an organic solvent such as kerosene or mineral oil saturated with oxygen will not rust because of the absence of water.

    [​IMG]

    Figure 19.9.1" role="presentation" style="display: inline-table; font-style: normal; font-weight: normal; line-height: normal; text-align: left; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">19.9.119.9.1: Rust, the Result of Corrosion of Metallic Iron. Iron is oxidized to Fe2+(aq) at an anodic site on the surface of the iron, which is often an impurity or a lattice defect. Oxygen is reduced to water at a different site on the surface of the iron, which acts as the cathode. Electrons are transferred from the anode to the cathode through the electrically conductive metal. Water is a solvent for the Fe2+ that is produced initially and acts as a salt bridge. Rust (Fe2O3•xH2O) is formed by the subsequent oxidation of Fe2+ by atmospheric oxygen.
     

Share This Page