why is painting in metal prevent corosion?
102293
corrosion is caused by the chemical reaction of oxygen with the metal over time, thus causing rust.  In order to help preserve the metal, a layer of paint is used that will serves as a shield or barrier between the oxygen and the metal.
497397
Let's say you're really hungry. If I lock a cupcake in a metal box and give you the box can you get to the cupcake without a key?\n\nNope.\n\nMetal oxides work the same way. By coating a metal in a desirable oxide (ie. as in aluminium anodizing) you're sealing the unprotected metal from more harmful forms of oxidization. If oxygen can't react with the surface of the metal because its already reacted with something else to form an oxide. Because of that you just prevented further oxidization BY oxidizing. There's no key, no reaction, to further degrade the metal underneith.\n\nThere are other things besides oxide coatings that can keep good ole' redox at bay. One is called a sacrificial anode and its commonly used on exposed metal on things like oil rigs.
386364
actually, stainless steel can corrode.  There are different grades of stainless based on the amount of nickle, chrome and other additives that protect it from oxidizing, however, if those additives are in too small amounts (as in low grade stainless), it can rust.  It'll still be slower than regular steel but it is not in vincible.
1157885
There are a vast number of water soluble corrosion inhibitors.\n\nAt the simple end of the scale - Sodium nitrite, sodium tolytriazole, zinc phosphate, borates, molybdates, vanadates and chromates all inhibit rust.\n\nThere are also proprietary organic compounds (some phosphate esters, ethanolamides, etc) also inhibit rust.\n\nIt all depends on whether you want the inhibition to be short lived or long lived (nothing is "permanent") and whether the inhibition is an "in use" inhibitor (like, say, a corrosion inhibitor in cooling water) or "static" (like phosphate "rust converters" used prior to painting.
716754
it prevents the steel from rusting. Zinc rusts too, but more slowly than steel, and it doesn't tend to eat away it's structure. \nZinc coatings prevent oxidation of the protected metal by forming a barrier, and by acting as a sacrificial anode if this barrier is damaged. Zinc oxide is a fine white dust that (in contrast to iron oxide) does not cause a breakdown of the substrate's surface integrity as it is formed. Indeed the zinc oxide, if undisturbed, can act as a barrier to further oxidation, in a way similar to the protection afforded to aluminium and stainless steels by their oxide layers.
798
Well I experienced that it secreted something that glowed white in blacklight... but could be some perfume etc. too...\n\nskin can corrode metal... maybe because it secretes acids. I do not now how organic acids interfere with fabric colours, especially nonpermanent ones...
71181
to prevent rust/oxidation
147407
Rusting is a chemical process that, can take place in metals exposed to the atmosphere. Not all metals however rust. Rusting is common with the metal, iron. Certain conditions in the air around a metal have to be present for iron to rust. Iron rust which, generally appears brown, is itself a chemical compound quite different from the iron itself. The rusting of iron can be prevented. In towns and large cities where iron sheets are used for roofing houses, rusting can also take place if the iron sheets are not protected from rusting. \n\nRust is the common name for a very common compound, iron oxide. Iron oxide, the chemical Fe2O3, is common because iron combines very readily with oxygen -- so readily, in fact, that pure iron is only rarely found in nature. Iron (or steel) rusting is an example of corrosion -- an electrochemical process involving an anode (a piece of metal that readily gives up electrons), an electrolyte (a liquid that helps electrons move) and a cathode (a piece of metal that readily accepts electrons). When a piece of metal corrodes, the electrolyte helps provide oxygen to the anode. As oxygen combines with the metal, electrons are liberated. When they flow through the electrolyte to the cathode, the metal of the anode disappears, swept away by the electrical flow or converted into metal cations in a form such as rust.\n\nFor iron to become iron oxide, three things are required: iron, water and oxygen. Here's what happens when the three get together:\n\nWhen a drop of water hits an iron object, two things begin to happen almost immediately. First, the water, a good electrolyte, combines with carbon dioxide in the air to form a weak carbonic acid, an even better electrolyte. As the acid is formed and the iron dissolved, some of the water will begin to break down into its component pieces -- hydrogen and oxygen. The free oxygen and dissolved iron bond into iron oxide, in the process freeing electrons. The electrons liberated from the anode portion of the iron flow to the cathode, which may be a piece of a metal less electrically reactive than iron, or another point on the piece of iron itself.\n\nThe chemical compounds found in liquids like acid rain, seawater and the salt-loaded spray from snow-belt roads make them better electrolytes than pure water, allowing their presence to speed the process of rusting on iron and other forms of corrosion on other metals.
250184
While the corroded part of the copper shield will have altered conductivity, there still is a metal surface - the border to the patina - where metal conductivity occurs. There might be a slight increase in resistivity, but not significant compared to contact corrosion.
350950
Unfortunately, I don't really have much information on this subject.  However, a galvanized nail (Galvanized is a protective layer around the outside of the screw to prevent rusting, or basic contact with the 'elements.') probably is the reason that the experiment is failed.  When will they start producing specific projects for these kids!?  Geesh.
150659
You may be referring to a sacrificial anode?\n\nSometimes, in order to prevent something from rusting (like a metal water pipe or the hull of a ship), you sacrifice a more reactive metal to corrode first.\nFor example, if you wanted to protect an Iron water pipe from rusting, you could electrically conect it to a "sacrifical" piece of Magnesium (a more reactive metal)m this way, the Mg will corrose first, keeping the Iron safe.\n\nEdit:\nYou wouldnt mix the sacrifical metal in with the metal your trying to protect, then you'll just get an object with a bunch of holes in it (where the other metal was eaten away).  You would electrically connect the sacrifical electrode to the other metal with a wire or something of that sort, then as the sacrificial electrode is corroded away, the other metal stays perfectly intact.\nI think in real life Magnesium is a very common metal to use since it is so high up in the reactivity series and not insanely expensive. Silver doesnt corrose very much at all, it wouldnt work as a sacrifical electrode, not would it need one very badly.
1027806
When shipping anything metal that has the potential to experience a salt water environment, coat the object in a substance called Cosmoline, which is a waxlike substance that prevents oxidation and corrosion.  It can be found at any Hardware store or Gun shop.
108960
Rust is the common name for a very common compound, iron oxide. Iron oxide, the chemical Fe2O3, is common because iron combines very readily with oxygen -- so readily, in fact, that pure iron is only rarely found in nature. Iron (or steel) rusting is an example of corrosion -- an electrochemical process involving an anode (a piece of metal that readily gives up electrons), an electrolyte (a liquid that helps electrons move) and a cathode (a piece of metal that readily accepts electrons). When a piece of metal corrodes, the electrolyte helps provide oxygen to the anode. As oxygen combines with the metal, electrons are liberated. When they flow through the electrolyte to the cathode, the metal of the anode disappears, swept away by the electrical flow or converted into metal cations in a form such as rust.\n\nFor iron to become iron oxide, three things are required: iron, water and oxygen. Here's what happens when the three get together:\n\nWhen a drop of water hits an iron object, two things begin to happen almost immediately. First, the water, a good electrolyte, combines with carbon dioxide in the air to form a weak carbonic acid, an even better electrolyte. As the acid is formed and the iron dissolved, some of the water will begin to break down into its component pieces -- hydrogen and oxygen. The free oxygen and dissolved iron bond into iron oxide, in the process freeing electrons. The electrons liberated from the anode portion of the iron flow to the cathode, which may be a piece of a metal less electrically reactive than iron, or another point on the piece of iron itself.\n\nThe chemical compounds found in liquids like acid rain, seawater and the salt-loaded spray from snow-belt roads make them better electrolytes than pure water, allowing their presence to speed the process of rusting on iron and other forms of corrosion on other metals.
236628
Corrosion occurs when a material is exposed to oxygen (oxidation). The best way to avoid oxidation is by protecting the material from coming in touch with the oxygen by painting over it or sealing it in any other way.
521265
All metals do not "corrode."  Some metals oxidize, such as iron turning to rust and silver turning black.\nSome metals do not oxidize, such as gold and platinum.\nNo health care professional would put a metal into your body if it rusted, corroded, or deteriorated in some other way.  The fact that the rods are 30 years old should be proof that your rods are not corroding.\nYour doctor should be the one to explain the term "hot."
1176918
a chromate coating applied to metals to make the surfaces corrosion resistant. (prevent rust)
1161774
because it stops corrosion to the steel which would rust and therefore increases the shelf life of the wire the same as it would mig or gas welding filler\n\ngaz