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  1. #1
    Join Date
    Jul 2021
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    Europe
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    27
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    21

    Default Metallization / zinc metal spray gun

    Im finding nothing on google with this device as DIY, but its really just either metal wire or powder dumped into gas-fuel flame thats then fired directly onto bare metal with great adhesion.
    I like to fix up my own car, my car is from 1999 and doing quite well but rust is a problem, and a zinc spray gun would be flawless for dealing with rust, acquiring zinc wire might be somewhat difficult, but ive seen there are devices available to turn TIG welding more mechanical, a handheld wirefeed, if you will- however zinc powder is not very difficult to manufacture on your own. Just dissolve zinc metal in sodium hydroxide = sodium zincate. Run electricity through 2 stainless electrodes in this solution = zinc powder. As for the powder feed you might want not too fine powder, maybe adjusting the volt/amp is how you decide what size powder you get- doable.
    I can even imagine making loads of money doing this lightspeed zincplating on cars- why is this not a thing anywhere? Could it be really difficult to put this device together? I lack a home workshop so i would be limited to trying to create this thing at my job and ive previously gotten naggy supervisor when i put together a DIY spot welder (which, is apparently the safest machine you can make because too low voltage to even penetrate skin).
    I have also seen aluminium wire being fed into this metallization spray gun, aluminium wire is pretty easy to get hold of.
    Could there be an issue getting zinc metal to stick to steel, they make it seem so easy in videos. I have tried to slowly melt zinc metal on steel plates getting zero adhesion, which is really confusing because with zinc plating they just dip steel in molten zinc and i really doubt that they etch all the rust or surface dirt off first.

    https://weldinginsider.com/thermal-spray-welding/
    https://www.airoshotblast.net/blog-images/99.jpg
    https://www.youtube.com/watch?v=G08dNd3QQlI

  2. #2
    Join Date
    Jul 2016
    Location
    Melbourne
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    33
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    1,351

    Default

    All the aerosol zinc would be very very bad for you. I have done a bit of spray mettalisation and there is a fair bit more to it than you would think. Also cold galvanisatipn products already exist.

    Sent from my SM-G973F using Tapatalk

  3. #3
    Join Date
    Oct 2011
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    Norwood-ish, Adelaide
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    56
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    5,926

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    Quote Originally Posted by Zeth4500 View Post
    I like to fix up my own car... but rust is a problem, and a zinc spray gun would be flawless for dealing with rust...I can even imagine making loads of money doing this lightspeed zincplating on cars- why is this not a thing anywhere?
    It would be great if the zinc was applied onto bare metal before the rust took hold. If not, all you are doing is trapping the rust underneath the zinc (if it sticks)

    Quote Originally Posted by Zeth4500 View Post
    I have tried to slowly melt zinc metal on steel plates getting zero adhesion, which is really confusing because with zinc plating they just dip steel in molten zinc and i really doubt that they etch all the rust or surface dirt off first.
    There is generally a velocity component to metal spraying to encourage a bond.
    As for hot dip galvanising, your slow melt technique to coat steel probably failed because temperature is critical - a little too high and the zinc starts oxidising. The advantage of a zinc dip bath is that as well as heating the steel to just the right temperature, the molten zinc excludes the oxygen where the bond is forming. The chemistry is more complex than it would seem as from memory there are something like 3 or 4 iron-zinc compounds that form under the metallic zinc. Galvanisers will refuse work if the steel is too rusty or dirty. Prefered prep is sand blasting to remove scale, rust and dirt before dipping

    Michael

  4. #4
    Join Date
    May 2011
    Location
    Murray Bridge S Aust.
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    69
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    4,891

    Default

    [QUOTE=Zeth4500;1989212]Im finding nothing on google with this device as DIY, but its really just either metal wire or powder dumped into gas-fuel flame that's then fired directly onto bare metal with great adhesion.
    I have also seen aluminium wire being fed into this metallization spray gun, aluminium wire is pretty easy to get hold of./QUOTE]

    I used to work n a place that did coatings as you're wanting to do. The metal has to be sandblasted first for removal of the mill scale and for adhesion of the coating. The process of applying the coating is extremely noisy, mainly from the Oxy/Acetylene combination, it requires a LOT of the gas mix, from memory they had sets of bottles that were combined, something like 9 bottles in a cage.
    If you were looking at it as a repair for rusted out sections, without relacing the metal, IT WON'T WORK, as the heat will melt the previously applied spray, not like soldering to fill a hole.
    It's not an easy as it looks operation, and was NOT cheap to apply. Also, if you were looking at doing this as a DIY at home, the neighbours would be most upset.
    Could there be an issue getting zinc metal to stick to steel, they make it seem so easy in videos. I have tried to slowly melt zinc metal on steel plates getting zero adhesion, which is really confusing because with zinc plating they just dip steel in molten zinc and i really doubt that they etch all the rust or surface dirt off first.
    Zinc plating is an electrolysis process, whereby the zinc bar is attached to the negative of an electrical current, and the item to be coated is to the positive side, the whole thing is immersed in a solution of something that escapes my mind atm. The surfaces are required to be ultra clean for the process to adhere. Sometimes, you'll come across something that's been Zinc plated and the plating is starting to lift, because it hasn't been cleaned properly, even a finger print will be enough to start the lifting.
    The process you describe of dipping the steel in molten zinc is a process called Galvanising. The metal object is placed in a bath of acid to remove any paints, oils, mill scale etc. Then goes through several more baths to rinse the acids off, heated dry to remove ALL moisture, then into the Zinc bath, after it then goes through a few more baths to finish the process.
    HTH,
    Kryn
    To grow old is mandatory, growing up is optional.

  5. #5
    Join Date
    Jan 2004
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    Mackay North Qld
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    Hi Zeth4500,

    Welcome to the MetalWork Forums

    To help you explore the other areas of our forum here's a guide on to to navigate our Forum and find all the interesting places.

    Goto the FORUM box in the top left hand cnr of the page and click the down arrow. This will bring up a pull down menu that has Forum Home at the top

    Click Forum Home which will present a scroll down page.

    Our rules,the Terms of Service are right at the top ,we encourage you to read them.

    Below that are all the various areas and sub forums that make up out MetalWork forums.


    Welcome

    Grahame

  6. #6
    Join Date
    Jul 2021
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    Europe
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    Default

    From the videos im seeing them adhering zinc coating it doesnt seem like a very major amount of gas is being used, currently my job is chopping up steel with a 2m long butane-oxygen torch, we get cages ov 12 50L oxygen bottles at 200bar, im assisting one guy at our job that does this every day, he will spend almost one whole cage in a day if hes cutting nonstop, we have a oxygen output at 10bars on the torches. I know personally buying 2.5L oxygen cost me about 60 euros and if i bought 5L it would be 100 euros, once you scale up the order size it gets a lot cheaper- anyhow my point is, i dont think they really use that much oxygen because the flames would also have to be oxygen-negative to avoid burning up the zinc powder or wire, the flames dont seem that aggressive- they probably just have a cage of oxygen bottles because its cheaper to order in bulk and they dont have to carry them around. If metallization really does make a lot of noise, do they maybe attach pressurized air or maybe some inert gas to give the zinc vapors a kick? The flames seem quite calm, at least compared to the nozzles im using thats rated for 400mm steel penetration.
    Zinc burns with a really nice emerald green flame, it burns very well with a powerful torch as i experienced today, i also noticed many of the painted components turned yellow when heating them, evidential of zinc in the paint, but whats really cool about metallization is that its practically heat resistant, contrary to paint. With zinc metal being directly on the metal, such as on the exhaust which gets super hot, it doesnt decompose and shred off.
    Cleaning the car would be a problem and DIY sandblaster isnt too technical, i bet you could use dirt if you dry it out well before use and pull it through a crude metal sieve, dirt does contain a large amount of aluminium oxide, which is used as abrasive, and some sand too.

    I guess making your own paint would work for larger surfaces, or for a much quicker job since superfine zinc powder is very easy to make with electrolysis (of sodium zincate) but im going for that extra technological step, i want to perfect it, also once the metal starts corroding, it will just peel the zinc paint right off, it will just chip off, and im not sure if the zinc in the paint is really 100% effective at preventing this, it would probably be only the zinc in the paint directly in contact with the steel, so maybe 5% of the zinc would even be a naive guess of efficiency?

    You can attach zinc anodes like on a ship, but it wouldnt work very well as it would all have to be in contact with water to work well, maybe if one was to place zinc anodes on the underside of the car and then apply some conductive gel- but that would again probably just prevent water entirely from getting to the steel.

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