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The story of titanium

construction-physics.com

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Re: The story of titanium

#81

Post by cphajduk »

A_D_E_P_T wrote: post #63

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…

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.

Re: The story of titanium

#82

Post by pasabagi »

kragen wrote: post #79
pasabagi wrote: post #75

Earlier quoted context omitted.

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?…

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

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.

Re: The story of titanium

#84

Post by Animats »

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

Re: The story of titanium

#85

Post by A_D_E_P_T »

kragen wrote: post #77
A_D_E_P_T wrote: post #63

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…

> 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…

> 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.

Re: The story of titanium

#86

Post by kragen »

pasabagi wrote: post #82
kragen wrote: post #79

Earlier quoted context omitted.

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

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.

that's maybe an exaggeration; people still make buildings out of flint, they make it into perfect spheres for ball mills, and when flintlock was the firing mechanism of choice, they shaped flints for rifles out of it. the main reason we don't have a lot of flint goods around is that, aside from its edge-forming powers, it doesn't have great properties: it's brittle, nonconductive and not all that pretty, much like unglazed fired clay

you can grind it into whatever shape you want if you're careful about silicosis

Re: The story of titanium

#87

Post by Vicinity9635 »

I have a titanium chainmail shirt: https://www.etsy.com/listing/505806057/titanium-chainmaille-... (me in 2nd pic)

It weighs just 6.6 lbs. (the page says 6.5 but I had to have him add a bit cause I got too swole in the lats a couple of years ago.)

It's fun to have someone try it on then watch them struggle as they can't figure out how to get it off lol

If you bend over and stick your arms down it basically slide off on its own.

What's really interesting is the ringing sound it makes when you play with it or move around wearing it, it's a noticibly higher pitch than steel is.

I also have a necklace/spacepen lanyard, wallet chain, and coif made of titanium by Bim also. My keyrings and bottle opener are also titanium. It's such a cool metal. Kind of a pity it makes a very poor knife blade. Speaking of: I also replaced the screws and hinges of my bespoke Benchmade knife with titanium ones, because why not?

A bit obsessed as you can tell.

tl;dr I have a mithril shirt

Re: The story of titanium

#88

Post by A_D_E_P_T »

cphajduk wrote: post #81
A_D_E_P_T wrote: post #63

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…

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…

You can make a general benchmark assumption, e.g. in the Reactivity Series:

https://en.wikipedia.org/wiki/Reactivity_series

So from a high enough vantage point, Ti is very slightly less reactive than Al, less reactive than Mg, and not too far from Fe. A far cry from being "a streetwalker" of a metal.

Re: The story of titanium

#90

Post by stevenwoo »

kylehotchkiss wrote: post #32
303uru wrote: post #12

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.

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

Titanium needs to be in a bigger tube with thinner walls to take advantage of the properties compared to steel - the very first titanium bicycles used the available surplus tubing from defense/aeronautics industry that was close to steel bicycle tubing size and were notably not great until they used slightly bigger tubing and better titanium alloys. Forks have a couple of design features that make it hard to work with titanium tubing, the height from bottom of headtube to where the top of the tire is has to have extra space for clearance or a tiny object or some mud will clog up the fork pretty quickly or cause an immediate stop in front wheel rotation, and that part of the fork has to be extremely stiff. Some of of the first carbon forks had a titanium steerer tube for a minimal weight saving and to make it easier to work with the stem attachment system. Several equipment changes to this part of the bicycle have come about in the last couple of decades to accommodate carbon fiber more easily. The market for titanium was just too niche by comparison to make those changes necessary.
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