[HN Gopher] The story of titanium
___________________________________________________________________
The story of titanium
Author : weird_user
Score : 146 points
Date : 2023-11-23 16:43 UTC (6 hours ago)
(HTM) web link (www.construction-physics.com)
(TXT) w3m dump (www.construction-physics.com)
| robwwilliams wrote:
| Great overview: Titanium production technology essentially
| "willed into existence" by the US government (mainly the military
| branches) but now critical in health care for implants that embed
| with bone and that do not induce rejection.
| danielodievich wrote:
| As a kid in my father's workshop we had several 4mm thick
| titanium plates, scavenged from some industrial stuff in USSR
| research facility nearby. I had a lot of fun getting my visiting
| friends tey to dent it with hammers. No matter how hard you
| struck it just didn't care. Only the oxidation patina would show
| some trace of impact. It was absolute magic to me. And so
| incredibly light!
| cyberax wrote:
| When the USSR collapsed, a lot of defense companies pivoted to
| civilian production. A factory in my town was producing
| titanium shovel heads.
|
| They were awesome, unbelievably light, but very durable. They
| also made nice sparks when dragged across concrete pavement.
| hef19898 wrote:
| Damn, imagine having a titanium shovel! I want one!
| avs733 wrote:
| https://nearzero.co/products/shovel
|
| They exist! Meant for backpacking/back country work.
|
| I spent a summer as a wilderness search and rescue
| intern/volunteer/grunt/mule during college and was shocked
| at how much weight could have been saved with better gear.
| There's just a minimal market for it.
| amluto wrote:
| That company sells titanium pots, too. And they say "
| Titanium leaves no metallic smell or taste."
|
| I don't believe it. Titanium is, mechanically, a great
| material for a lightweight pot, but in my limited
| testing, I don't think it's inert enough. Green tea in a
| titanium pot is especially nasty.
| therein wrote:
| I had similar experiences with titanium cookware. Could
| it be acting as a catalyst to something that would
| otherwise not happen?
| amluto wrote:
| I don't know.
|
| My current favorite cooking surface is the coating used
| on Hestan Nanobond. It's sold as "titanium" but, from
| reading the patent, I think it's a bunch of layers of
| CrN, TiN, and AlN, applied by PVD in a process optimized
| to produce an attractive gray color that looks a bit like
| metallic titanium. It seems very hard, very durable, and
| does not obviously react with any kind of food. (And even
| if it did, unless something oxidized the Cr to +6 and
| made it soluble, nothing that might leach out seems
| likely to be harmful.)
|
| The patent seems to expire fairly soon, and maybe the
| process will take off. I wonder if this coating could be
| applied to a lightweight titanium pot with good results.
| OfSanguineFire wrote:
| In the backpacking and bicycle-travel community, titanium
| pots are widely regarded as good only for boiling water
| in, since they don't distribute heat as well as aluminium
| for more complex cooking.
| WillAdams wrote:
| This is actually a plot point in H. Beam Piper's _Little
| Fuzzy_:
|
| https://www.gutenberg.org/ebooks/18137
|
| the audiobook read by Tabithat is just about professional
| quality and is highly recommended:
|
| https://librivox.org/little-fuzzy-by-h-beam-piper/
| myself248 wrote:
| Decades ago, Sears sold magnesium stepladders. I've used one,
| and it's freakishly light, a 6-foot step ladder that you can
| walk around with balanced on one finger.
|
| I've always wondered what a titanium one would be like.
| petertodd wrote:
| A lot heavier actually.
|
| In an application like a stepladder, you have to work with
| certain minimum dimensions for the stepladder to be
| practical (eg rungs and sides have to fit in the hands
| nicely). You also have to have certain minimum thicknesses
| on the parts to have sufficient resistance to local
| deformation (eg dropping a hammer on the rungs). That
| forces the parts to be significantly larger and stronger
| than they otherwise would be. Which makes very lightweight
| metals like magnesium and aluminum the better choice, as
| you can make thick parts at the required dimensions at very
| little weight.
|
| Climbing gear is a great example of this. Even though
| there's a segment of that market for which money is no
| object, the only use for titanium in climbing gear is
| certain specialized applications where corrosion resistance
| is important. Eg fixed gear mounted on sea-side cliffs.
| Because climbing gear has to have certain minimum
| dimensions to avoid damaging ropes, the very low density of
| aluminum wins over titanium's higher density/higher
| strength.
|
| If you made a carabiner out of titanium it'd be stronger
| than necessary, and a lot heavier.
| londons_explore wrote:
| If you can 3D print titanium, then you can make a
| honeycomb structure overcoming this problem.
| bch wrote:
| What is the response to stress by this build method? Will
| it fail gracefully over a lifetime of stresses? Any
| single big stress-event?
|
| In terms of (rigid, diamond-frame) bicycles, this is why
| I'm still firmly in the steel camp. No aluminium, no
| carbon; just steel. It really does have an excellent
| combination of nice ride quality, low weight, high
| strength, good failure mode (I've broken a few frames,
| and they tend to just bend/sag, vs the rapid unscheduled
| disassembling of carbon/Al).
| londons_explore wrote:
| I can't comment on the plasticity of titanium.
|
| But complex microstructures can be designed to have non-
| sudden failures. Eg. you could ensure that a visible
| crack appears at 0.75x the ultimate strength, yet doesn't
| fail till 1.0x the strength.
|
| You can also design structures so that a 'crack' is
| either 1mm wide or not there at all (ie. no hairline
| cracks).
|
| such features of microstructures are not free though -
| you will lose strength/weight to get them.
| jabl wrote:
| > Decades ago, Sears sold magnesium stepladders. I've used
| one, and it's freakishly light, a 6-foot step ladder that
| you can walk around with balanced on one finger.
|
| As a slight aside, magnesium is also a very interesting
| material. It _might_ be we 're on the cusp of a major
| expansion in magnesium usage due to recent advancements
|
| - Mining from seawater (about 1 kg Mg in 1000L of
| seawater), or existing brine tailings from other extraction
| activities. With cheap solar electricity this might drive
| the cost down considerably (below the extremely dirty
| production methods being used today in China), providing
| carbon-emission free production of essentially unlimited
| amounts.
|
| - thixomolding, a die-casting / injection molding-like
| process where the material isn't completely melted
| (thixotropic state), producing parts with much less
| porosity than traditional die casting.
|
| - New alloys that are less prone to fires and corrosion.
|
| For slightly more details, see
| https://www.youtube.com/watch?v=OIv_Rfl0L_A
| petertodd wrote:
| Those must have been soft hammers. Titanium isn't magic. It's
| neither as hard, nor as strong, as steel. It's a lot lighter,
| which makes it a wonder material in certain applications that
| can take advantage of it's excellent strength-to-weight ratio.
| But if max hardness, or strength at a given size, is what you
| are after, without a weight constraint, steel wins.
| saberience wrote:
| I mean, I'm no materials scientist but one google tells me
| that Titanium is AS strong as steel but much less dense. I
| just browsed through the top 10 Google results and everyone
| states that titanium is roughly equal to steel in strength
| but with various other benefits. So your comment is
| definitely off-base somewhere, you make it seem like steel is
| much stronger, which clearly isn't the case.
| AlotOfReading wrote:
| Steel's strength varies by orders of magnitude depending on
| the alloy and heat treatment. It's an incredibly flexible
| family of materials. Some members of that family are far
| stronger than anything in the titanium family, e.g. 4340
| steel has a nominal yield strength of >1800 MPa, compared
| to <1300 MPa for Ti 10-2-3.
| saberience wrote:
| We're not talking about exotic and expensive varieties of
| steel though. We're just talking about "general" or
| common steel and comparing it to unalloyed
| "common"/"general" titanium. Remember, Steel is itself an
| alloy, Titanium is an element.
|
| If you start comparing Titanium alloys to Steel then the
| comparison gets even harder. Titanium alloys are in
| general stronger than steel as well as much lighter and
| more corrosion resistant.
| petertodd wrote:
| > We're not talking about exotic and expensive varieties
| of steel though.
|
| 4340 steel isn't exotic. It's one of the most commonly
| used grades of steel out there, and it's much cheaper
| than titanium. There are steels out there with
| significant stronger yield strengths too. Meanwhile the
| highest yield strength of any Ti alloy is <1300MPa.
|
| Titanium is still a really great material in certain
| applications. But it's not magic. You have to use it
| intelligently in the right application to get a benefit
| from it.
| bch wrote:
| The family of materials we call steel is so fantastic, it
| almost a shame it's so ubiquitous that we take it for
| granted. If it were invented today the front page of HN
| would be loaded with stories of this miracle material.
| MeImCounting wrote:
| Pure elemental titanium has much less desirable material
| properties than various titanium alloys which are what
| you encounter most commonly. It is very uncommon to
| encounter elemental titanium outside of a chemistry lab.
| metal_am wrote:
| Grade 1 is still pretty common for ultralight backpacking
| items like pots and pans due to its ductility.
| MeImCounting wrote:
| Thats cool! I didnt know there were specific common
| applications where grade 1 would be desirable compared to
| the stronger alloys available.
| petertodd wrote:
| Read this for starters:
| https://www.thomasnet.com/articles/metals-metal-
| products/ste...
|
| "When comparing the tensile yield strengths of titanium and
| steel, an interesting fact occurs; steel is by-and-large
| stronger than titanium."
|
| Many people confuse this issue, because they're actually
| talking about measures of strength/weight ratios, on which
| titanium does really well. But if you are size limited
| rather than weight limited, steel is often a better
| material than titanium even when cost is no object.
| saberience wrote:
| Every source says that titanium is as strong as the most
| commonly used steel. Sure if you're going for lesser used
| alloys of steel you may as well compare to lesser used
| alloys of titanium. Or just compare iron with titanium,
| as that's really comparing one element with another, and
| is the "fair" comparison.
|
| And anyway, your original comment suggested someone was
| totally in the wrong for thinking a 4mm titanium plate
| was strong, which is obviously incorrect. 4mmm of
| titanium plate is clearly going to be really strong and
| resistant. They wouldn't make plane engines from it if it
| wasn't.
| petertodd wrote:
| > They wouldn't make plane engines from it if it wasn't.
|
| ...but they don't! Jet engines can only use titanium for
| certain low pressure, low temperature, sections. The high
| temperature parts are made from nickle/iron-based
| superalloys. And aluminum still gets significant usage,
| because for many geometries an aluminum part has a better
| strength/weight ratio.
|
| Like I said, titanium is strong. But it's not magic.
| Stronger than any aluminum alloy, weaker than commonly
| used steel alloys. Hitting a 4mm plate of titanium with a
| hammer just isn't a very special experience. I've done
| it.
|
| Hitting a 4mm _tool steel_ plate definitely can be a
| special experience. Because it 's so strong and hard that
| you could easily cause the thing to shatter, sending
| sharp shards in unpredictable directions...
| MeImCounting wrote:
| No the parent is correct. Steel is by and large stronger
| than titanium of the same size. Pray tell what is this
| "most commonly used alloy of steel"? Because just fyi
| different steel alloys are used for different
| applications just like different titanium alloys are also
| used for different applications.
|
| Titanium has excellent strength to weight properties
| compared to steel. A 4mm titanium plate would absolutely
| be dented by common shop hammers. This doesnt mean that
| "titanium isnt strong" it just means they have different
| material properties.
| petertodd wrote:
| Exactly.
|
| Indeed, if your design goal is strictly "don't get dented
| when hit by a hammer", the "strongest" material could
| easily be a good synthetic rubber!
| MeImCounting wrote:
| For most non-architectural design goals striking the
| right balance of toughness strength and hardness is
| generally what you want correct? I would imagine for
| building a bridge you care much more about elasticity and
| creep strength.
| petertodd wrote:
| Also fatigue resistance.
|
| Bicycle design is a good example of where this matters:
| steel has a significant fatigue limit, and can endure
| cyclic stresses below that limit indefinitely. Aluminum
| has no fatigue limit, so any flexing is inevitably eating
| away at fatigue life. Thus aluminum bike frames have to
| be made much stronger and stiffer than otherwise
| necessary, to avoid bikes breaking unexpectedly due to
| fatigue. And that in turn means that aluminum bike frames
| don't have as much of a weight advantage over steel as
| you'd expect.
| janc_ wrote:
| Right now, top quality steel bike frames at the minimum
| bike weight allowed by the UCI are stronger than top
| quality carbon fibre bike frames of the same weight.
| Aluminum frames of the same weight would not be
| considered usable probably... (Pro cyclists would still
| use carbon fibre bikes because they can be made more
| aerodynamic).
| robotomir wrote:
| I had a titanium Tissot watch and it scratched easier than
| steel watches.
| Turing_Machine wrote:
| The article mentions that the Soviet Union had lots of titanium
| ore, and also that it was heavily used in the A-12/SR-71 family
| of aircraft.
|
| I remember reading elsewhere that the CIA set up a bunch of
| front operations across the world to buy titanium (or maybe
| titanium ore) from the USSR without them finding out what it
| was being used for. They didn't want the "Ship to:" part of the
| order form reading "Lockheed Skunkworks, Burbank Califoria".
| Heh.
| latchkey wrote:
| This is the 5th time this story has been posted here. None of the
| other times received any comments and only a few points.
| pmarreck wrote:
| It's the first time I've seen it, and I'm glad I did because
| it's fascinating!
|
| Also, this time seems to be going a bit differently... Perhaps
| timing is everything (see: bored people with their Thanksgiving
| families today...)
| kylehotchkiss wrote:
| It started with the titanium iPhone didn't it? Maybe more
| people have begun to understand the benefits practically
| fuzzfactor wrote:
| The timing of the submission is far more important than the
| nature of the article.
|
| Time of day, time of week, other prominent distractions, etc
| have an increasingly outsized influence.
| pmarreck wrote:
| This is a really interesting story!
| scrlk wrote:
| I can't help but recall Steve Jobs introducing the PowerBook G4
| Titanium:
|
| > "Titanium! It's made out of titanium! Like the spy planes! This
| is an incredible material, it's stronger than steel yet lighter
| than aluminium."
|
| https://youtu.be/bNHkrnU77m0?t=92
| Ingaz wrote:
| I had IBM notebook with titanium case (before it became Lenovo)
| kylehotchkiss wrote:
| I could see a day when titanium laptops return. Apple has
| invested in the some of the best mass machining in the world. I
| wonder what it'd look like sandblasted like their laptops and
| with their new coatings.
| 303uru wrote:
| Love titanium, something so cool about it. It's like steel with
| no downsides. I've got 5 ti bikes and a few ti watches, one of my
| favorite pieces though is my snow peak double wall titanium mug.
| JonChesterfield wrote:
| What makes the mug particularly good? Always interested in
| something to improve coffee and recently broke my favourite
| one.
| psb217 wrote:
| I've got a Ti double-walled mug from Snow Peak that I use a
| lot around the house. The big strengths are light weight,
| near indestructability, and a cool Ti functional aesthetic.
| It's double-walled and holds heat well, but I prefer the
| "mouth feel" of ceramic or glass when drinking coffee, so I
| don't use it much for coffee.
| petertodd wrote:
| I've got one myself. For only a bit more weight (~70g) than
| single-walled aluminum mug (~60g), Snow Peak can put two
| walls, making the mug insulated.
|
| Though it's heavier than an insulated plastic mug, and _way_
| more expensive.
| 303uru wrote:
| It's super light, about the same weight as single wall
| stainless cup. The mouthfeel is nice, hot coffee doesn't make
| the titanium feel as hot as steel gets and the feel is more
| similar to ceramic than stainless steel. It cleans up really
| nice and truly doesn't stain. I even used a dc transformer to
| do some custom anodizing on mine and it looks really cool.
| carabiner wrote:
| Lightweight for camping. I have a titanium flask that was
| engraved by a guy on YouTube.
| amluto wrote:
| Tea, especially green tea, in a titanium mug is, in my
| experience, utterly gross.
|
| Maybe anodized titanium would work better? I don't know what
| the chemistry behind the problem is, but even stainless steel
| kills green tea after a while.
| throwaway920102 wrote:
| Titanium is not good for flavor, its good for strength to
| weight ratio for people concerned with weight (think EDC,
| ultralight, etc)
| kylehotchkiss wrote:
| Do your bikes have carbon forks or TI? when I looked at TI
| bikes for fun in the past, the carbon forks surprised me,
| seemed like that should have been titanium too. How has your
| mug held up? Has it been compatibly durable compared to steel
| vacuum mugs? Snow peak makes great products but leans more
| lightweight than durable from my experience with their dishware
| opan wrote:
| Snow Peak's titanium spork is awesome as well. I got two and
| use one for my regular meals and the other I EDC in a cargo
| pocket for use away from home.
| megraf wrote:
| Resting next to me is a titanium ring, it is extremely light,
| resistant to ambient temp change, and is usually cool to the
| touch. It cost $15 or so. It wears in a really beautiful way,
| aging like it's enjoying itself.
|
| On my finger is a tungsten carbide ring, it's extremely dense
| (that of gold, slightly heavier than uranium), and has a lot of
| interesting properties. It's warmed quickly by my fingers, and
| rings the most beautiful tone when I strike it with some bar
| stock of AI.
|
| Wolfram has been a very nice metal in my life, I wish it was more
| common, and would love to try to add some knurling to it.
| kylehotchkiss wrote:
| I wear a titanium ring too and keep my real one safely locked
| away. It's an incredible metal that I proudly wear around. Mine
| cost about the same.
|
| I also have a titanium pocketknife (James Brand), carabiner,
| keyrings, pens, camera (fujifilm makes a few), and some beloved
| snow peak dishes. And the silly titanium iPhone. It's such a
| great metal to make things to carry with.
| efitz wrote:
| It's not that great for blades as it doesn't retain its edge
| as well as steel and is harder to sharpen.
| nico_h wrote:
| It's usually the frame and sides / scales that are made of
| titanium, never the blade afaik.
|
| Except maybe in some multitool keyring single piece
| doohickeys, but it's not expected to cut anything beside
| the tape on your packaging.
| MeImCounting wrote:
| Titanium so widely desirable for knife scales because of
| not only its strength to weight benefits but also
| interesting finishes that can be applied for instance
| anodization can give incredibly beautiful iridescent
| colors in a wide spectrum of potential colors and tones.
| I dont know how interested you are in modding your pocket
| knife but there are several very talented people that can
| do just stunning colorful and textural finishes on
| titanium.
| q7xvh97o2pDhNrh wrote:
| Do you mind sharing where you got the titanium keyrings and
| carabiners?
|
| I've been searching forever for decent keyrings. There's a
| few carabiners (though the titanium ones are hard to find
| there too, and usually covered in obnoxious branding). But
| keyrings especially seem to be an under-served market.
| There's either (1) the usual mass-produced, flimsy, cheap
| garbage, or (2) something tougher and more expensive, but
| covered in branding.
|
| I've settled with (2) for now (though it's not even
| titanium), but it'd be nice to not have to look at a giant
| billboard every time I pull out my keys.
| drcongo wrote:
| I have a nickel allergy so titanium is my first port of call
| for jewellery, though my wedding ring is zirconium and some of
| my old, pre-allergy stuff is now plated with rhodium.
| Ingaz wrote:
| Great article! Sad it's so USA-centric. It would be great to read
| "Soviet part" of titanium
| kylehotchkiss wrote:
| The real story now is how China centric it is - a lot of the
| worlds machining capabilities for it are still only there.
| ratsmack wrote:
| A little info in the subject.
|
| https://history.stackexchange.com/questions/28152/when-and-h...
| MeImCounting wrote:
| I collect nice pocket knives. Many nice pocket knives are made
| from titanium and other fancy materials like carbon fiber. I love
| titanium above all other metals for its unique properties in
| being anodized and finished in a large variety of beautiful ways.
| If you are ever interested in seeing some truly unique and
| beautiful titanium finishes check out "Knife Modders" on
| instagram. Combinations of coatings/anodizing/laser etching can
| produce some truly beautiful pieces.
| stevefolta wrote:
| How can titanium be both a "streetwalker" and "incredibly
| corrosion-resistant"?
| kragen wrote:
| same as aluminum, it immediately forms a hard and adherent
| oxide layer upon exposure to air or especially water
| hdivider wrote:
| Huge fan of Titanium.
|
| If only we could find a cheap way to get the metal out of
| titanium dioxide. Like a Haber process-level breakthrough.
|
| Then we could start replacing steel with titanium in many
| applications. Think entire freight trains, cargo ships,
| containers, cars, trucks, tractors -- all that heavy steel
| replaced by titanium alloys.
|
| Enormous quantities of fuel and energy saved by lower density and
| higher strength. In many applications, it would likely make
| stainless steel obsolete.
|
| Trillions of dollars of value may be locked up in such a
| breakthrough.
| pocketstar wrote:
| Fatigue is why we use steel for everything, no other alloys
| have the practical strength and infinite life.
| petertodd wrote:
| Like steel, titanium alloys have a distinct non-zero fatigue
| limit, and thus can be engineered to have infinite fatigue
| lives. Though the exact details differ and steel or titanium
| can be better depending on exactly what the conditions are.
| softfalcon wrote:
| You are correct in that steel is harder and stiffer than
| titanium. Steel is also more re-usable, smelt-able than
| titanium.
|
| However, when it comes to fatigue (which I assume, you are
| referring to fracture strain) titanium has a significant
| edge. The fracture strain for steel is roughly 15%, but for
| titanium alloys, it often reaches and exceeds 50%.
|
| I don't say this to contradict you, but to point out that as
| with most things in life, "it depends".
|
| Source: https://www.ulbrich.com/blog/titanium-versus-steel-a-
| battle-....
| Gibbon1 wrote:
| A better argument for steel is it requires 5-10 kwhr/kg to
| produce vs 60kwhr/kg for aluminum and 250kwhr/kg for
| titanium. So for the same energy you get 6 times more steel
| than aluminum and 25 times more than titanium. Which seems
| to say when the properties are steel are acceptable it's
| the cheaper option.
|
| https://solar.lowtechmagazine.com/2009/06/how-much-energy-
| do...
| pasabagi wrote:
| I think it could be one of those 'grass-is-greener' scenarios.
| Steel is really nice to work with. It's strong and elastic and
| you can do all sorts of things to alter its properties, like
| even in a home shop.
|
| Titanium always looks really hard to work with, just from the
| few times I've seen youtube types get some into their lathe
| chucks.
|
| Would the added (in some ways just different) performance make
| up the difference? No idea. I mean, would people use so much
| aluminium if it wasn't straightforward to extrude it into
| interesting shapes? I don't think I would.
|
| The straight characteristics of a material are one thing: what
| you can actually do with it are another.
| kragen wrote:
| maybe if the blast furnace hadn't been invented nearly a
| thousand years ago we wouldn't be so familiar with the
| techniques that work well on steel
| pasabagi wrote:
| That's true. On the other hand, people have been working
| with flint for longer than there have been people, and it
| remains fiendishly hard to make anything with it.
| painted-now wrote:
| I owned a carbon road bike - which unfortunately I wrecked due to
| a problem with my chain. I then bought a used titanium bike, and
| I have peace of mind since then. It might be just a psychological
| effect - but it just feels good to have a bike frame that's
| extremely difficult to destroy.
| vermooten wrote:
| Come back, zinc! Come back!
| A_D_E_P_T wrote:
| Almost everything about the article is wrong, oversimplified, or
| misleading.
|
| Take this paragraph, for instance:
|
| _> But despite its abundance, it 's only recently that
| civilization has been able to use titanium as a metal (titanium
| dioxide has been in use somewhat longer as a paint pigment).
| Because titanium so readily bonds with oxygen and other elements,
| it doesn't occur at all in metallic form in nature. One engineer
| described titanium as a "streetwalker," because it will pick up
| anything and everything. While copper has been used by
| civilization since 7000 BC, and iron since around 3000 BC,
| titanium wasn't discovered until the late 1700s, and wasn't
| produced in metallic form until the late 19th century._
|
| As this is basically a bunch of bullet points in paragraph form,
| it'll be easier to handle if we break it down:
|
| _> But despite its abundance, it 's only recently that
| civilization has been able to use titanium as a metal (titanium
| dioxide has been in use somewhat longer as a paint pigment)._
|
| The same also applies to aluminum, magnesium, nickel, etc.
|
| _> Because titanium so readily bonds with oxygen and other
| elements, it doesn't occur at all in metallic form in nature._
|
| The same also applies to aluminum, magnesium, and even iron. (I
| mean, there's some meteoric iron, but it's very rare.) Pure
| metals are very rare in nature. What distinguishes iron and
| copper from aluminum and titanium is the energy required to split
| the oxide into metal.
|
| _> One engineer described titanium as a "streetwalker, " because
| it will pick up anything and everything._
|
| Titanium is not more reactive than aluminum and it's far less
| reactive than magnesium. In fact, it's slightly less reactive
| than iron overall. (i.e., more chemically stable under normal
| conditions and in contact with common acids.)
|
| _> While copper has been used by civilization since 7000 BC, and
| iron since around 3000 BC, titanium wasn't discovered until the
| late 1700s, and wasn't produced in metallic form until the late
| 19th century._
|
| This has everything to do with the temperature required to
| separate the metal from the oxygen atoms binding it, and nothing
| to do with anything else. What's more, it applies even more
| strongly to aluminum, which was discovered in 1825 -- three
| decades after the discovery of titanium. (1791.) So there's
| absolutely nothing unique about titanium in this regard.
|
| I could go on. But basically this is an "I hecking love science"
| article that barely scratches the surface of the subject -- and
| still manages to be subtly misleading.
| kragen wrote:
| > _The same also applies to aluminum, magnesium, nickel, etc._
|
| the oxides of aluminum, magnesium, and nickel were not in use
| as paint pigments
|
| > _What distinguishes iron and copper from aluminum and
| titanium is the energy required to split the oxide into metal.
| (...) Titanium is not more reactive than aluminum_
|
| the particularly relevant issue here, as i understand it, is
| that titanium has a stable carbide, which prevents you from
| reducing it carbothermically; you end up with titanium carbide
| instead of titanium metal. aluminum's carbide is unstable even
| in water, while iron's carbide is mechanically strong but still
| easy to reduce to iron with air. copper's carbide is poorly
| characterized and even more unstable, and it even occurs native
|
| there are other things that titanium reacts more strongly with
| than aluminum does. titanium tetrachloride, for example, which
| is mentioned in the article, isn't a mere salt like normal
| chlorides; it's a volatile fuming liquid, because titanium
| forms _covalent_ bonds with the chlorine _like a motherfucking
| nonmetal_. you can argue about whether this makes it more or
| less reactive than aluminum in this context; the reaction
| produces more energy per metal atom but less energy per
| chlorine atom
|
| this kind of dirty trick is why titanium wasn't isolated until
| _decades_ after the creation of metallic calcium, sodium,
| potassium, aluminum, and even the isolation of some of the rare
| earths
|
| so i think the characterization in the article is fair
| A_D_E_P_T wrote:
| _> the oxides of aluminum, magnesium, and nickel were not in
| use as paint pigments_
|
| Aluminum oxides were used as a pigment, predominantly in blue
| (cobalt aluminum oxide) but also in white.
|
| In any case, the dominant white dyes of the Early Modern
| period -- and prior periods -- were lead based. The presence
| of TiO2-based pigments is actually one good way to identify a
| modern forgery.
|
| _> the particularly relevant issue here, as i understand it,
| is that titanium has a stable carbide_
|
| This turned out to be solvable via calciothermic or
| magnesiothermic reduction -- which is now effectively the go-
| to method for just about everything that can't be reduced
| with carbon. All titanium dioxide reduction processes demand
| quite a lot of energy, though; more than aluminum and far
| more than iron.
| cphajduk wrote:
| The article may be an oversimplification, but your comment is
| an equal oversimplification. There are many environmental
| conditions that need to be assumed when comparing reactivity.
|
| For instance, if you have pure Titanium, pure Magnesium, pure
| aluminum in a vacuum at room temperature and proceed to
| introduce oxygen, you get the following reactions (simplified
| elemental chemical reactions, the Enthalpy of formation is what
| is important here):
|
| Ti + O2 -> TiO2 (Std. Enthalpy of formation is -945kJ/mol)
|
| Mg + O -> MgO (Std. Enthalpy of formation is -601kJ/mol)
|
| 4Al + 3O2 -> 2 Al2O3 (Std. Enthalpy of formation is
| -1675kJ/mol)
|
| As a result, aluminum is most reactive, followed by titanium,
| then magnesium.
|
| This is the reason why aluminum is used in solid rocket motors
| and various other explosive devices.
|
| Under different conditions, these numbers may change: for
| instance a reaction with water instead of air may yield
| different enthalpies. At quick glance in water, titanium is
| actually least reactive when compared to aluminum and
| magnesium.
| euroderf wrote:
| Great discussion here. I can pretty much see why people would
| make a career of metals engineering.
| dave333 wrote:
| There is evidence titanium may be the cause of the rare disease
| yellow nail syndrome:
| https://en.wikipedia.org/wiki/Yellow_nail_syndrome
|
| study ref: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3176400/
| Animats wrote:
| Machining titanium is possible, but remains difficult. It's slow
| and you go through a lot of cutters.
|
| Now this is just showing off.[1] Daishin and Open Mind started
| with a 60 kilogram cylinder of titanium and milled a very
| detailed crown out of it. 300 hours of CNC machining time on a
| very good 5-axis mill. Most of the metal ends up as scrap.
|
| The software for this is called HyperMill. If you have to ask how
| much it costs, you can't afford it.
|
| [1] https://www.youtube.com/watch?v=Bqv5SjC4s6w
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