cleaning copper from steel
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From: hanson on 20 May 2010 18:56 "Peter Fairbrother" <zenadsl6186(a)zen.co.uk> wrote: Any ideas on how to clean copper from steel - the steel is HSS in expensive small bits, and should be left untouched. > hanson wrote: HSS = High Strength Steel = High carbon tool tips. The C-Fe is far more reactive then the Copper, especially in pH ranges below 8. So stay away from acids. > You may be successful with Anodic stripping in caustic pH 14 solutions, which will not attack the steel but form soluble Cuprates. Look up "Electro Cleaners". > However, the easy way to go is to call the peddler from the Chemical supply house and buy a commonly available == Alkaline Copperstripper for Steel ===, > These powdered alkaline strippers work even @ RT. They usually are formulations that contain an oxidizer and a complexing agent like these here: > Oxidizers: NH4NO3 = Ammonium Nitrate (NH4)2 SO5 = Ammonium Persulfate, NH4OH & H2O2 = Ammonia and Hydrogen peroxide (NO2)1-2 - Ph-COOH = Mono or Di-nitro Benzoic acid. > Alkaline Complexers/Chelates/Sequestrants: (NaOOC)2>NCH2CH2N<(CH2COONa)2 = ETDA NH4OH = Ammonia NH2-CH2-CH2-NH2 = Ethylene Diamine. NaCN, KCN = Sodium- or Potassium Cyanide. > Look up the Metal Finishing Guide Book. You'll see the exact formulations & use directions in there. > Long shot: Depending on your conditions, you may be successful with a quick dip of your bits into concentrated 65-68% HNO3, Nitric acid. -- HNO3, in the absense of water may flash oxidize the copper but passivate and save the steel. Cheap but nasty procedure though. > Same with cooking your bits in a saturated solution of KMnO4, Potassium Permanganate that contains 1-2 lbs NaOH, Caustic Soda/gal. step 2 is cooking off the formed brown MnO2, Manganese Dioxide, in a conc hot solution of NaOH + Sodium Gluconate. Jet engines are cleaned that way, for separating the copper residues off the steel matrix. > BTW, if you are successful, you'll need to bake your parts for 3-6 hrs at 375 to 400F, because the stripping causes Hydrogen embrittlement in the steel. W/O bake your reconditioned parts will break when used. > Good luck hanson
From: Peter Fairbrother on 21 May 2010 02:19 Peter Fairbrother wrote: > hanson wrote: >> "Peter Fairbrother" <zenadsl6186(a)zen.co.uk> wrote: >>> Any ideas on how to clean copper from steel - the steel is HSS in >>> expensive small bits, and should be left untouched. >> Long shot: Depending on your conditions, you may be successful with >> a quick dip of your bits into concentrated >> 65-68% HNO3, Nitric acid. -- HNO3, in the absense of >> water may flash oxidize the copper but passivate and save the steel. >> Cheap but nasty procedure though. > > Just tried it, nope. Just wondering - would some HNO3/HF or NHO3/HBF4 mixtures be worth trying? Got those in my cupboard, but I don't like to bring the HF and HBF4 out unless I have to. The composition of the HSS in question is: 0.88% C, 4.1% Cr, 5.0% Mo, 6.0% W, 2.0% V, rest Fe. -- Peter Fairbrother
From: Helmut Wabnig hwabnig on 21 May 2010 03:06 On Fri, 21 May 2010 07:19:44 +0100, Peter Fairbrother <zenadsl6186(a)zen.co.uk> wrote: >Peter Fairbrother wrote: >> hanson wrote: >>> "Peter Fairbrother" <zenadsl6186(a)zen.co.uk> wrote: >>>> Any ideas on how to clean copper from steel - the steel is HSS in >>>> expensive small bits, and should be left untouched. > >>> Long shot: Depending on your conditions, you may be successful with >>> a quick dip of your bits into concentrated >>> 65-68% HNO3, Nitric acid. -- HNO3, in the absense of >>> water may flash oxidize the copper but passivate and save the steel. >>> Cheap but nasty procedure though. >> >> Just tried it, nope. > >Just wondering - would some HNO3/HF or NHO3/HBF4 mixtures be worth >trying? Got those in my cupboard, but I don't like to bring the HF and >HBF4 out unless I have to. > >The composition of the HSS in question is: 0.88% C, 4.1% Cr, 5.0% Mo, >6.0% W, 2.0% V, rest Fe. > > >-- Peter Fairbrother Ultrasonic cleaning ultrasonic cleaner (Just my 2 cents). w.
From: Mark Thorson on 21 May 2010 10:07 Peter Fairbrother wrote: > > They are used for cutting channels in copper and have a very aggressive > rake and are best used dry, consequently the limiting factor in their > use-life is when they get copper adhered to them - the steel itself is > still sharp but the cutting edge is obscured by copper. Perhaps you could run the blade backward and cut some aluminum to clean off the copper.
From: dlzc on 21 May 2010 11:17
Dear Peter Fairbrother: On May 20, 9:49 pm, Peter Fairbrother <zenadsl6...(a)zen.co.uk> wrote: .... > The bits I want to clean are very small M2 (moly) HSS > slitting saws, 6mm dia and 1.2 mm thick. > > They are used for cutting channels in copper and have > a very aggressive rake and are best used dry, > consequently the limiting factor in their use-life is when > they get copper adhered to them - the steel itself is > still sharp but the cutting edge is obscured by copper. A couple of other options that make this a non-issue, is if you use a different method to make your "copper bread": - EDM machine the slices (very uniform, very slow, fairly expensive, rough surface) - water jet cutting - stamp the copper bits out of sheet Some options then based on you still needing to saw cut: - you have had several suggestions for cleaning if the copper was thin (a few atoms thick), apply them *before* the blade gets gummed. If you get 100 feet of cut before failure, what happens if you chemically clean the blade at 50 or 75 feet? - at what temperature does your HSS lose its temper? Copper melts at ~1100°C, you might be able to just sling off the "lumps", then chemically clean. (Suggestion by another poster). David A. Smith |