leeds Posted February 24, 2009 Share Posted February 24, 2009 At the weekend was talking about anodizing. Yes it can be easily done to aluminium. Can it be done to steel? It is as far as I am aware basically an electroplating technique so why isn't it used on steel as a decrotaive/protective finish? Regards Brendan Quote Link to comment Share on other sites More sharing options...
cipx2 Posted February 24, 2009 Share Posted February 24, 2009 This link answers your question: http://en.wikipedia.org/wiki/Anodization Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted February 24, 2009 Share Posted February 24, 2009 Can it be done to steel? Yes! Its called rust! Al. Quote Link to comment Share on other sites More sharing options...
cipx2 Posted February 24, 2009 Share Posted February 24, 2009 Actually there are some chaps over the pond who said it can be done and patented it . Quote Link to comment Share on other sites More sharing options...
GBMUD Posted February 24, 2009 Share Posted February 24, 2009 Zinc passivate with a coloured lacquer is a common decorative and protective finish for steel parts, often seen in gold or silver. I believe that there are other colours becoming available now. Chris Quote Link to comment Share on other sites More sharing options...
roybatty666 Posted February 24, 2009 Share Posted February 24, 2009 At my old engineering company we used to "chemical Black" our jigs and tooling t stop your hands rusting them. t was also a tough anti chip/scratch coating Quote Link to comment Share on other sites More sharing options...
leeds Posted February 24, 2009 Author Share Posted February 24, 2009 Thanks for your replies folks. This enquiry was the result of an idle conversation. I never realised that an anodised coating was porous so unsuitable for steel. The idea of zinc passivation sounds interesting and might be an alternative to powder coatings. Powder coatings are not so good on sharp edges and once the coating starts to lift rust can quickly spread underneath the coating. Whilst aluminium does not corrode/rust par se it is suseptible to bi metallic or electrolytic corrosion. I used to have ali dropped forged carabiners in my caving days. These 'corroded' due to the pitting from general knocks received underground and presumably from the slightly acidic nature of cave water. It was possible to peel the outer skin off these karabiners which exposed the 'granular' texture of the core of the carabiner. Fortunately when they looked horrible they were still above the rated strength as I had access to tensile test machines. Regards Brendan Quote Link to comment Share on other sites More sharing options...
Anderzander Posted February 24, 2009 Share Posted February 24, 2009 Yes! Its called rust! Bingo! Quote Link to comment Share on other sites More sharing options...
landmannnn Posted February 24, 2009 Share Posted February 24, 2009 Frosts do a diy kit to chemical black steel for about £35. link Quote Link to comment Share on other sites More sharing options...
integerspin Posted February 25, 2009 Share Posted February 25, 2009 passivation is usuall done on zinc plate, I say usally as it's onnly done on plate as far as I knowbut someone is bound to know better than me. Look under the bonnet of a car, see the gold nuts and bolts, or sometimes black or olive green. Generaly all the steel bits that aren't painted[unless it's a roller, I think they had some plated and passivated prior to painting]are plated and passivated. You can anodise Titanium as well as ali, handy to know when you have a landy. Quote Link to comment Share on other sites More sharing options...
nas90 Posted February 25, 2009 Share Posted February 25, 2009 Anodising aluminium was first used in the aircraft industry mainly because anodising increases the skin hardness of aluminium. It also forms a layer to prevent corrosion which the underwater users want to prevent corrosion in a salt water environment. Aluminium is fairly soft and anodising makes it that bit better to resist abrasion. With powder coating it is very important to radius edges to prevent chipping of the paint. Structural steel can be hot zinc sprayed or hot dipped galvanised and then powder coated. I did this on a lot of parts for the nas a few years ago and although some of the powder coating has chipped-off the galvanising is still protecting the steel. Hot zinc spray is especially good for parts which may distort when dipped in hot tank for galvanising. Zinc and passivate is an electrolytic process and has a few microns thickness, hot zinc spray coats the surface much like a paint spray gun and galvanising is dipped into a tank and you can get 'runs' of zinc with galvanisers not taking too much care. Both hot zinc and galvanising add a fairly thick coat and the cost of both processes is a factor of the amount of (expensive) zinc used. Quote Link to comment Share on other sites More sharing options...
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