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Science

How To Tell If It's Really Titanium 280

Posted by Zonk
from the hold-your-credit-card-to-a-grinder dept.
With the growing popularity of titanium, some disreputable merchandisers are passing off other materials as the more expensive metal. Popular Science looks at a surefire way to prove what that credit card/crowbar/ring is really made of. "Hold any genuine titanium metal object to a grinding wheel (even a little grindstone on a Dremel tool will do), and it gives off a shower of brilliant white sparks unlike any softer common metal. The sparks are tiny pieces of cut titanium--the friction of the grinder heats them till they burn white-hot. Hold a grindstone to the shackle of a "titanium" padlock from Master Lock, however, and you'll instead see the telltale fine, long, yellow sparks of high-carbon steel."
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How To Tell If It's Really Titanium

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  • by pwizard2 (920421) on Tuesday December 25, 2007 @01:29PM (#21815428)
    The method in TFA sounds like it would really scratch up whatever you're trying to test. Is there a way to run a test without damaging the object?
    • Density test (Score:3, Informative)

      by Ostsol (960323)
      If the object in question is constructed from a single material, then a density test should work. Use water displacement and a scale to determine the volume and mass, respectively. From that you can calculate the density and compare the value to the actual density of titanium. Of course, this won't work if the object merely has titanium components and it cannot be disassembled. . .
    • High carbon steel isn't magnetic or what?
      • Re: (Score:3, Informative)

        Useful trivia:
        Steel is a blend of iron and carbon. Mostly iron, in all its incarnations, and iron is always magnetic.

        High-carbon steel is very hard but a bit brittle, while steels with less carbon will usually deform before they crack. There is always a compromise between hardness and toughness.
        • Re:a magnet? (Score:5, Informative)

          by Kazymyr (190114) on Tuesday December 25, 2007 @02:42PM (#21815900) Journal
          ...iron is always magnetic.

          That is a big fallacy. There are some alloys in which iron is around 98-99% which are non-magnetic (think unusual alloying elements like niobium and rhenium).
          • Re: (Score:2, Insightful)

            Absolutely fascinating, but iron is an element (Fe), not an alloy.
        • by Fex303 (557896)

          Mostly iron, in all its incarnations, and iron is always magnetic.
          You've never tried to stick a magnet to a stainless steel fridge, have you?

          Useful trivia: Magnetism is slightly harder than you think.

        • Re: (Score:3, Interesting)

          by budgenator (254554)
          Steel is actually an alloy containing predominately iron, usually has a good amount of precipitated Ferric Carbide crystals , ferric-Carbide in solution with the iron and often trace elements and occasionally minute amounts of pure carbon which is detrimental. The amount of carbide in solution and precipitated greatly controls the physical properties of the metal and is controlled by the heat treatments the steel is exposed to during manufacture.
      • Re:a magnet? (Score:5, Informative)

        by LynnwoodRooster (966895) on Tuesday December 25, 2007 @03:01PM (#21816018) Journal
        Nope. Get above 0.15% carbon or so and you lose almost all the magnetic properties of iron. It's one reason that loudspeakers are made with low carbon steel (usually 1006, 1008, or 1010 grade) since you get too much carbon and the flux no longer flows well, meaning you need a LOT more magnet and a higher grade magnet to get the same flux in the gap.

        And yes, I am a loudspeaker engineer... ;)

        MERRY CHRISTMAS!

      • Re: (Score:3, Interesting)

        by necro81 (917438)
        Most steels are magnetic to various degrees. However, when designing some stuff that would be used in an MRI suite, I did some research and found that some grades of stainless steel - specifically, 300-series [wikipedia.org] stainless steels (302, 304, 316, etc.) - are more or less nonmagnetic [physlink.com]. They can't be used inside the bore of the scanner, but that's mostly because it screws up the uniformity or the magnetic and RF fields necessary for imaging. This was a handy discovery for me, because sometimes aluminum and plast
    • I'm not a scientist, but maybe you user laser on the object at a defined temperature to see what kind of metal it is? I'm pretty sure they've been doing this stuff for a while!
    • by Dan East (318230) on Tuesday December 25, 2007 @02:13PM (#21815716) Homepage Journal
      Yes, there is a better way, and your concern about damaging expensive objects - particularly jewelry - is quite justified. Simply send the object to one of my two testing centers (conveniently covering both hemispheres - one is located in Russia, the other in Africa) and we will send you a full report of the object's composition.

      Dan East
      • by necro81 (917438) on Tuesday December 25, 2007 @04:39PM (#21816546) Journal
        How much are you paying for that service? For $30,000-40,000, you can buy a handheld x-ray fluorescence analyzer [niton.com]. These things got started in testing for lead paint, and now get used to test and check for lots of things - including alloy composition verification. An XRF shines x-rays of a known energy at the test sample, then detects and analyzes the spectrum that is reflected back. Each element has a characteristic x-ray emission spectrum based on the energy of electrons dropping into lower shells. In 10-20 seconds, you can get a really good breakdown of the elements in the test sample.
    • by ByteSlicer (735276) on Tuesday December 25, 2007 @03:11PM (#21816076)
      A laser spectrometer [wikipedia.org] can do this for you. It will still create microscopic damage though.
    • by rs79 (71822)
      "The method in TFA sounds like it would really scratch up whatever you're trying to test. Is there a way to run a test without damaging the object?"

      Titanium is the only metal hydrogen peroxide reacts with.

      Grinding titanum in considered very dangerous. It can explode.

      Whoever wrote the article is seriously undereducated.

    • Re: (Score:3, Interesting)

      by arivanov (12034)
      A good test is with fuming Concentrated Nitric Acid or "royal water" - mix of Nitric Acid with Sulfuric, the one that dissolves gold. It will also dissolve nearly anything else on earth even group 8 noble metals.

      Titanium is passivated in it and does not dissolve or show any signs of damage (except in extremely high saturation fuming nitric acid). At the same time it happily dissolves is hidrocloric, hidrofluoric acid. It will also dissolve in sulfuric acid even in low concentrations. IIRC it did not like th
    • If the object is solid, why not use the archimedes principle?
      It worked for gold, why not for titanium?
    • Re: (Score:3, Interesting)

      by Mspangler (770054)
      x-ray fluorescence. There are portable "guns" that can do this now, for only about $30,000.

      The old ones took up a room, had a radioactive source, and the spectrometer had to be cooled with liquid N2.

      The modern PMIs are pretty nice. Point at a piece of metal, pull the trigger, and in 5 seconds it tells you if it is 304, 316, C-276, 800HT, or whatever. If the metal is not in the database, then it tells you the elemental makeup so you can look it up, and if it's a real alloy enter it into the database. If it'
    • Re: (Score:3, Funny)

      by berashith (222128)
      Exactly my thought. I don't think it would go over too well if my wife found me with my wedding ring in a vice while holding a grinder. The only thing to make it worse would be if I had forgotten the safety goggles again.
  • by grassy_knoll (412409) on Tuesday December 25, 2007 @01:30PM (#21815440) Homepage
    Think the store will mind if I bring a dremel with grinding wheel to the store with me? For testing purposes of course...
  • Good news (Score:5, Funny)

    by Anonymous Coward on Tuesday December 25, 2007 @01:34PM (#21815470)
    Apparently my wife's jewelry was all genuine titanium!
  • by $RANDOMLUSER (804576) on Tuesday December 25, 2007 @01:37PM (#21815500)
    It heats white hot almost instantly, and when you thumb the oxygen cutting lever, you get the most amazing shower of white sparks - like fireworks - very pretty!
  • by Ed Pegg (613755) * <ed@mathpuzzle.com> on Tuesday December 25, 2007 @01:41PM (#21815524) Homepage
    The author of this Popular Science article, Theo Gray, also recently relaunched http://www.periodictable.com/ [periodictable.com] Thousands of elemental pictures and videos are available there, all linked in with his Popular Science series.
  • When I tested adamantium, it gave off a shower of brilliant white sparks as well.

    But they were so hot they caught my workshop on fire.
  • by dacarr (562277) on Tuesday December 25, 2007 @01:50PM (#21815574) Homepage Journal
    One thing to keep in mind is that sales droids are probably not familiar with the wonderful world of minerology and/or science minded. They are sales people for a reason. They aren't the people who understand these concepts. (If anyone should understand the concept, it is you, the reader.) So as such, if you go and apply a dremel tool to, say, a platinum wedding ring you have in mind for your wife and, lo and behold, it's showering yellow sparks, the first thing through their mind is not going to be something to the effect of "aw dammit, I've been found out!", it's going to be more like "Holy f*ck! This f*cker just damaged my merchandise! POLICE!". You can't talk logic into them, and the police are more likely to side with the jeweler. Sure, you might be able to prove the jeweler wrong in a court of law and countersue for false advertising (and expose him as a fraud), but having to fart around with legal crap for months is, for one, not my idea of a good time.

    This is very much a point where Hanlon's Razor can be applied.

  • Aluminum burns quite well. It's just that it is so soft that the grindstone doesn't get it hot enough to ignite.
    • We were ready to pop some Jiffy Pop [wikipedia.org] at a campfire, when then noticed it had a warning "do not use in campfires." We tried it anyway... the aluminum foil pan burned in to nothing before the popcorn popped, so we were left with just the steel handle.
  • Ow! Shit! (Score:5, Funny)

    by schon (31600) on Tuesday December 25, 2007 @01:56PM (#21815610)
    Man, I just tried this with a new package of Energizer Tianium, and the spray burned a hole through my skin!

    You can be sure I'll be returning these "titanium" batteries just as soon as I'm back from Emergency!
  • A few simple ones (Score:5, Informative)

    by BlueParrot (965239) on Tuesday December 25, 2007 @02:01PM (#21815642)
    a: Titanium is not ferromagnetic, and hence it is not attracted by magnets as strongly as iron is ( the difference in force should be orders of magnitude ).
    b: Titanium's density is 4.5g/cm^3 , iron is 7.8g/cm^3
    c: Titanium is corrosion resistant to dillute sulfuric and hydrochloric acid, iron is not.

    • Re:A few simple ones (Score:4, Informative)

      by florescent_beige (608235) on Tuesday December 25, 2007 @03:54PM (#21816310) Journal
      It's hard to determine the density of something like a ring because even if you weight it you don't know its volume. But there is a way around that, weigh the item in air then in water and take the ratio of the weights. A jewelry store would be more open to that idea than coming at the thing with a power tool. Here's the arithmetic: volume of item = v density titanium = d_t density water = d_w weight in air w_a = v*d*g weight in water w_w = w_a - v*d_w*g w_w/w_a = (w_a - v*d_w*g)/w_a = 1 - d_w/d_t plugging in d_w = 1 g/cc d_t = 4.5 g/cc w_w/w_a = 1 - 1/4.5 = .78 If it's steel: w_w/w_a = 1 - 1/7.8 = .87 Most jewellers would have a setup that can weigh something immersed in water, it's how they tell themselves what the material is. If they say they don't then you are probably being had.
      • by dave1g (680091)
        ...or you could have a... uh... eureka! moment [wikipedia.org] and just dunk the ring in water to measure the change in volume. and then use the volume and previous mass measurement to find the density. But I suppose either method is valid, and just as difficult since they both involve a scale and water.... but one has more historical significance.
        • Re: (Score:3, Informative)

          It's effectively the same thing but the weight ratio is more practical. The volume of jewellery is so small that reading the change in water level in a graduated cylinder is really hard. It's generally smaller than the meniscus.

          Plus most jewellers are already set up to do the water-weighing.
    • by TubeSteak (669689)

      c: Titanium is corrosion resistant to dillute sulfuric and hydrochloric acid, iron is not.
      Ummm.. how dilute?
      I have the extra links from my Fossil Blue Titanium watch that I can test.
  • by Poromenos1 (830658) on Tuesday December 25, 2007 @02:02PM (#21815654) Homepage
    Next up: Test if your explosives have gone bad by detonating them.
  • GRIND THIS! (Score:4, Funny)

    by denzacar (181829) on Tuesday December 25, 2007 @02:11PM (#21815706) Journal
    Apparently, Google [google.com] has "interesting" sense of humor regarding titanium products.
  • by monoqlith (610041)
    Don't try this with your Powerbook G4 Titanium.
  • by steveha (103154) on Tuesday December 25, 2007 @02:14PM (#21815720) Homepage
    I read a story about a couple who loved bicycling (and loved their titanium bicycle frames). They decided to have rings made from titanium.

    One day the guy had some kind of accident, and his ring finger was mashed; it swelled up badly. They took him to the emergency room. In the ER, someone got out the cutters to cut the ring off the swollen finger. Whoops, titanium. The cutters (probably simple diagonal cutters) had no problem with the usual soft gold rings, but titanium was too hard! They wound up getting a Dremel tool or the equivalent and cutting the titanium ring off (very carefully, I imagine).

    The moral of the story: if you get a titanium ring made, maybe you should wear it like a necklace.

    P.S. Merry Christmas everyone.

    steveha
    • They can be cut off. (Score:3, Informative)

      by raygundan (16760)
      I know an ER doc who thought the same thing, until somebody came into her ER with one, and it was as trivial to cut off as anything else. Even if they lack a proper cutting tool, you can just squeeze it until it shatters. Titanium is strong, but it's not like a ring made of the stuff is somehow immune to being cut or broken. Hospitals are full of interesting tools, and it sounds like even in your story, they improvised fairly well.
    • by Nexzus (673421) on Tuesday December 25, 2007 @02:47PM (#21815936)
      About 18 years ago, I was on an underwater oil-drilling rig, when the mission we were "tasked" to perform by the navy went horribly wrong, and the rig started taking on water. I was running frantically running through cold freezing water towards a closing hydraulic door. I didn't make it in time, but I stuck my hand in the opening, and the door was stopped by my titanium wedding band. A colleague had found me, cut the hydraulic power to the door, and saved me. Earlier I had almost flushed it down the toilet. Good thing I didn't.

      Couple hours later I met some aliens.

      (Yeah, I know, but it sounds better in 1st person.)
    • Re: (Score:3, Informative)

      by 1729 (581437)
      Actually, titanium rings can be cut off fairly easily, at least according to the guy who made my wedding band:

      http://boonerings.com/faq.htm#4 [boonerings.com]

      Tungsten carbide rings are difficult to cut, but they can safely be cracked with vise grips:

      http://www.trewtungsten.com/remove.php [trewtungsten.com]
  • Probably it does not matter with my titanium dive knife if I have to grind into it a bit, I could actually sharpen it as well (not that it is not razor sharp already)m but the question is if you want to really grind into that titanium fancy case, that pen, or other "cool" device you just got.

    I was honestly hoping for a less destructive testing method. On the other hand just for curiosity, I really would not buy titanium for the "bling" factor, only for its strength and weight. And where you need those, you
  • Hello Customer Service. This pile of titanium dust is what's left of your expensive titanium product after I tested it to ensure that you weren't lying. I expect it to be replaced by a brand new product immediately, now that I know you're honest. Thank you very much!
  • I have a large Seiko titanium wrist watch that I invested in a few years ago. To this day it's interesting to hand it to someone and see the look on their face when they take it. It's rather plain-looking and "feature-free" for something so frickin' expensive, but when they feel how light it is, they can hardly believe it. I must have very acidic sweat because I rot leather and canvas watch bands like crazy and metal bands actually corrode away on me. This is the first watch I've owned that has literall

  • I tried the method with my tennis racket. Indeed, it *was* titanium.
  • Marketing BS (Score:2, Insightful)

    by Anonymous Coward
    All the titanium hype is just pure marketing BS anyway.

    They're capitalizing on the idea that titanium is high-tech and expensive. Which it is. But that's relative steel
    and aluminum. Aluminum costs about $2,500 a (metric) ton. Titanium, on the order of $50,000/ton. Contrast that to gold, which'll cost you around $25,000,000/ton.

    So titanium jewellery? I'll pass. In fact, I read an article where a metals wholesaler said that he didn't even bother to charge for the small amounts used for designer jewellery.

    It's
    • by athakur999 (44340)
      Titanium is one of the few metals I can wear for a significant amount of time without my skin breaking out. The only others I know is pure gold. Everything else I've tried, even those labeled as "hypoallergenic" cause me to begin to break out after a few days.

      Since a pure gold jewelery would be both expensive and scratch up very easily, that leaves titanium for my wedding band and my watch. I wish I could find something a bit heavier though. Titanium jewelery is not very substantial feeling due to its l
      • by notnAP (846325)
        Indeed, many people have similar problems, myself included. For this reason, I don't wear any jewelry, and even my gold wedding band (not 24k) caused occasional problems. (Divorced now, so problem resolved.)

        More significantly, I do need to wear glasses, and contacts don't agree with me. As was mentioned in another comment [slashdot.org], many people have bad reactions to even hypoallergenic frames. After going a month or two constantly coating my frames with clear nail polish to avoid the blistering rash I got everywhere

  • by Colin Smith (2679) on Tuesday December 25, 2007 @04:46PM (#21816586)
    Titanium is a woman's metal. Real men use Tungsten.
     
  • by edwardpickman (965122) on Tuesday December 25, 2007 @05:13PM (#21816736)
    We were building a rig for a show and there were a lot of surplus aitcraft parts around. I found a large bracket that was perfect but it needed an extra hole drilled in it. The piece was light enough I assumed it was aluminum. I was using a hardened drill bit that should have cut through stainless. After five minutes I checked it and I barely scratched the surface. Aircraft Aluminum can be fairly hard but it seemed rediculous so I tried again but still nothing. I flipped over the part and there stamped/cast on the otherside was Titanium. Needless to say I gave up. All I managed to do was kill a good drill bit. If it seems really light for it's size and can't easily be scratched there's a good chance it's Titanium.
  • by sectionboy (930605) on Tuesday December 25, 2007 @05:42PM (#21816842)
    someone please tell me how to tell if there's real platinum in my Capital One® platinum Card, I always want to know.
  • by SvnLyrBrto (62138) on Tuesday December 25, 2007 @07:18PM (#21817356)
    Titanium and steel may very well spark in the manner he describes. But this little gem, so far as I'm concerned, renders everything he says suspect:

    it was just aluminum, which doesn't burn.

    Aluminum most certianly *DOES* burn. Though fairly difficult to ignite, aluminum burns ferociously and spectacularly and is notoriously difficult to extinguish, as the crew of the HMS Sheffield learned much to their dismay. The fuel of the Space Shuttle's solid rocket boosters is aluminum. And aluminum is the fuel component of thermite.

    I think that the "scientific" opinion of anyone so clueless as to try to claim that aluminum won't burn should be discarded with the lowest grain of salt

    cya
    john

    • by c6gunner (950153)
      I'm sure he meant to say "it was just aluminum, which doesn't burn while being ground".

      Let's not assume stupidity where a simple misunderstanding is possible.
  • by CODiNE (27417)
    Powerbook owners where are you??
  • by Anonymous Coward
    Hmmmm...I wonder if this works with magnesium?
  • No dremel? (Score:3, Interesting)

    by ed1park (100777) <ed1park @ h o t m a i l .com> on Wednesday December 26, 2007 @12:53AM (#21819050)
    How bout a blow torch, chlorine gas or liquid oxygen? :)

    Even bulk titanium metal is susceptible to fire, when it is heated to its melting point. A number of titanium fires occur during breaking down devices containing titanium parts with cutting torches.

    When used in the production or handling of chlorine, care must be taken to use titanium only in locations where it will not be exposed to dry chlorine gas which can result in a titanium/chlorine fire. Care must be taken even when titanium is used in wet chlorine due to possible unexpected drying brought about by extreme weather conditions.

    Titanium can catch fire when a fresh, non-oxidized surface gets in contact with liquid oxygen. Such surfaces can appear when the oxidized surface is struck with a hard object, or when a mechanical strain causes the emergence of a crack. This poses the possible limitation for its use in liquid oxygen systems, such as those found in the aerospace industry.

    http://en.wikipedia.org/wiki/Titanium [wikipedia.org]

    Call me paranoid, but I think I'll stick to gold if I ever wear jewelry. But interesting to know if you're ever in a McGuyver type situation. :)

All this wheeling and dealing around, why, it isn't for money, it's for fun. Money's just the way we keep score. -- Henry Tyroon

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