[Adlan]

Marco mentioned the question in anther thread, and I thought it was interesting enough to start.

What are Plas Steel and Adamantium?

I always imagined Plas Steel as an advanced polymer, an STC material, which can be made from many different sources of the monomers and with trace elements in it to make it really strong. Quick and Cheap to Fabricate, with the right know how.

I always pictured Adamantium as being an Element as yet undiscovered, that lies in the next Island of Stability, the next Island of stability is the chemical hypothesis that although right now, as we make larger and larger elements, they decay radioactivly very rapidly, at some point further on, these large elements will again be stable.

This would make sense to me, as Adamantium is described as being very expensive and rare, and heavy.

What do you guys think?

[N01H3r3]

With regards to Plasteel, and any other steel used in the 40k universe, I tend to imagine that the techniques used to create the metals are significantly more advanced (and utilise techniques we cannot in their manufacture) - given that 'steel' is a broad term for a variety of iron alloys with carbon content in a specific range, this isn't particularly far-fetched, especially given that the Imperium has easy access to manufacturing conditions that we can only hypothesise about  - high, low and zero gravity being the ones that spring to mind first.

Plasteel in particular I imagine as a contraction of the correct term - Plasma-treated Steel - which refers to the particulars of heat treatment used in its production. Essentially, Plasteel is a steel-based superalloy that has been heat treated using high-intensity plasma furnaces. The specifics are a little beyond me - I only work with metallurgists, I'm not one myself - but it seems appropriate for the stated vagueness of the 40k universe while still sounding somewhat plausible.

Adamantium as a new element sounds appropriate, though I've never really thought about it to be honest.

On a similar note, I've always taken that the substance 'promethium' is actually a specific compound of the element promethium, more properly known as Promethium Fulminate, but at the same time, it's also become a colloquial term for a range of petrochemical substances of similar purpose (mainly because outside of the Mechanicus, the specifics of the difference aren't known, so nobody knows any better). Again, whether or not that's actually possible is unknown to me and not of any particular concern, but it sounds a little more plausible than there being the same name for two very different substances.

[RobSkib]

Prometheum differs from real-world petrol (or whatever you put in flamethrowers) becuase it ignites on contact with air, thus not needing a starter light at the nozzle.

[N01H3r3]

Prometheum differs from real-world petrol (or whatever you put in flamethrowers) becuase it ignites on contact with air, thus not needing a starter light at the nozzle.

Yes, but real-world promethium doesn't do that. At least, not to my knowledge.

[Koval]

Prometheum differs from real-world petrol (or whatever you put in flamethrowers) becuase it ignites on contact with air, thus not needing a starter light at the nozzle.

Nope. Volatile as it is, it does need a source of ignition to get it going.

If it did indeed ignite on contact with air then flamers would be more dangerous to handle than plasma weapons.

[Charax]

I would say the most likely explanation is that ¹⁴⁵Pm is used in conjunction with a component that ignites upon bombardment with Beta particles is mixed into the fuel component of Promethium to form the ignition compound.

Under pressure in the storage flask, there's no air to burn, but once exposed to air the beta decay of ¹⁴⁵Pm ignites this other component, which sets off the napalm-like fuel suspension. Once the fuel suspension starts to burn, it'll quickly reach the temperature at which Promethium itself burns (a modest 150 degrees). The sticky, burning, radioactive substance is more than nasty enough to be used as a weapon.

For this to work, Promethium would need to contain:
 - Promethium
 - some substance that ignites during beta particle bombardment
 - a fuel suspension - something that burns long and hot combined with a thickening agent,preferably with something else that breaks down into more oxygen
The name Promethium would then just come from one of the ingredients of this insane mixture, turning a beta-decaying radioactive metallic lethanoid into a gel-like burn-anywhere fuel source

[MarcoSkoll]

Well, as you say, Adamantium is dense and rare. It's also very durable and hard.

The name does imply that it's an element, but the truth is, if it were an as of yet undiscovered element, it would almost certainly be a lot rarer. What I like to think is that it's something we know of, but under a different name.
All though the name implies that it's an elemental metal, we shouldn't write off the possibility of it being some form of alloy either. Or possibly not a metal at all - after all, Helium's name would imply the same, but it's clearly not.

The closest real world equivalents are probably Elements 73-77: Tantalum, Tungsten, Rhenium, Osmium, and Iridium.
All dense, hard and pricey, these fit the bill pretty well. They vary between ductile (tantalum & rhenium) and brittle (tungsten, osmium and iridium); can be alloyed in various combinations with one another combining properties; have hard and dense carbides; and are highly corrosion resistant.

For that reason, my best guess is that it's one of those elements, an alloy of them, or perhaps even some form of carbide.

Plasteel is a bit harder to work out, and it depends on whether the plas is from "Plasma" or "Plastic"
I would suggest that it's NOT plastic, as Armaplas is already defined as a metal/plastic composite.

Thermoplas... no idea. Some heat resistant plastic? But that doesn't really explain why it would be in Land Raider armour. Although it's possibly some form of dilatant plastic, that hardens under impacts, which would explain why it was in flak armour.

While I'm at this, I'll bring up Ceramite. Little explanation is needed - some form of hard and heat resistant ceramic.

Prometheum differs from real-world petrol (or whatever you put in flamethrowers) because it ignites on contact with air, thus not needing a starter light at the nozzle.

They're inconsistent about that, and rightly so, as it's explicitly explained that promethium is just a generic term the fuel used in flamer weapons.

Personally, I think it's a bloody stupid idea to use such a self-igniting fuel - very dangerous (I can see obscene numbers of friendly casualties from filling mistakes, ruptured tanks...), and completely unnecessary.

Anyway, I personally see it as (usually, with regard to the original caveat) petrol that's modified or in some other way not suitable for vehicle use. But not all of it is - some may be self igniting, some may just be straight petrol, some may be modified petrol, some may be like napalm... lots of options.

~~~~~

In general, I work on the principle that the 40k periodic table is the same as ours in most respects, but that some elements have different names. It would be somewhat absurd for Einsteinium & Nobelium to got by those names in their universe for example.

So for example, the element we call Promethium (#61), wouldn't go by that name in their universe.

[N01H3r3]

The name does imply that it's an element, but the truth is, if it were an as of yet undiscovered element, it would almost certainly be a lot rarer.

Rarity is subjective; when dealing with a civilisation willing to mine planets hollow in under a millennium, material rarity seems like somewhat less of a concern than it is for us. Beyond that, the relative rarity of elements as we understand them today are a subjective matter due to our relatively limited viewpoint - we can only say what is rare on earth, which may or may not have any bearing on such things on other worlds elsewhere in the galaxy.

It may even be an artificial element - while the Imperium may be in technological decline, the technology they do have (quite aside from the applications that technology is used for - the disparity between the advancement of Imperial technology and the ways that technology is used seems to be quite a deliberate anachronism) is quite a bit more advanced than we are, even if knowledge of its function is limited to only a few. Just because we can't do it doesn't mean it's impossible...

[MarcoSkoll]

Beyond that, the relative rarity of elements as we understand them today are a subjective matter due to our relatively limited viewpoint...

I'm no expert on nuclear science, but as I understand it...

As far as natural abundance, we know that the heaviest element that can be formed by exothermic nuclear fusion is Mass 56 (Essentially, Iron, or a rare Nickel nuclide). And between 28 (essentially Silicon) and 56 is only formed in the largest of stars anyway.
Anything heavier can only be formed by the slow-neutron-capture-process in specific stars, or supernova. Whatever it is, if it's of natural origin, if it's "heavier" than 56, it was formed in a supernova.

The S-process can create up to mass 209 (Bismuth), and supernovas are capable of producing anything up to Atomic mass 254 (Californium, although it's only seen synthetically on Earth)
Anything beyond that is synthetic only. If Adamantium IS an element, and one that's not yet been discovered, it does not exist naturally.

Anyway, I'll be the first to admit that my theoretical chemistry is poor, but although "Islands of Stability" may exist, there is no great evidence that I know of that suggests that any of those chemicals will be a wonder metal as mentioned.

That's why I favour a theory that says it's something we already know of by a different name, or some specialised alloy (of known elements) that may well be manufactured and treated by techniques we don't yet know of.

[TheNephew]

Admittedly I didn't keep up my inorganic chemistry much further than Marco did, so I'm still no expert, but Marco's right about the relative abundances of the heavy elements - it's ridiculously unlikely that any metal as heavy as Adamantium should be would be available in significant amounts.

Having briefly brushed up on the subject:
I expect that any Adamantium-like that was found in the next 'stability island' would be used in a way similar to depleted uranium is now.
Since it would probably be a heavier, higher density metal, I suppose it would be used in cases of 'larger scale' applications - titans, superheavies, possibly ships [though that may be too big]. A second possibility is, since DU is currently extensively used as shielding, adamantium could be used for high-stress machinery like plasma/melta technology, Gellar field generators, ship drives and such.
High velocity penetrating shells/rounds, hard armour plating and perhaps shielding/blades for plasma/power/force weapons seem the likely military uses in the forty-first millennium, much as they are now.
Marco, if I've got the wrong end of the DU business, by all means challenge and correct it.

[MarcoSkoll]

Marco, if I've got the wrong end of the DU business, by all means challenge and correct it.

No, you're largely on the money. But it should be said that DU (Uranium 238) is still nasty stuff.
Although its half life is roughly the same as the current age of the earth (so it's pretty much stable), it's always found mixed with U-235, which is more radioactive, and it's hard to completely free the two.

It's also (unless I'm getting it wrong) somewhat toxic. So it's a good idea not to have it around too much.

Other than the less pleasant parts of DU, there's something to be said for Adamantium actually being U-238. However, my best guess remains that it's a special alloy of some of the five metals I listed earlier. The fact that it's called adamantium may well simply be a ploy by the AdMech to keep the actual details of such a special metal to themselves - which would also play a large part in its rarity.

EDIT: Minor correction

[N01H3r3]

Marco, if I've got the wrong end of the DU business, by all means challenge and correct it.

No, you're largely on the money. But it should be said that DU (Uranium 238) is still nasty stuff.
Although its half life is roughly the same as the current age of the earth (so it's pretty much stable), it's always found mixed with U-235, which is more reactive, and it's hard to completely free the two.

It's also (unless I'm getting it wrong) somewhat toxic. So it's a good idea not to have it around too much.

The radiation hazard of DU isn't small enough to entirely ignore, but it's worth noting that the risk from DU is far more because it's toxic, and pyrophoric in swarf and powder form (the latter making it extremely dirty and time consuming to cut, because you have to pour mineral oil over the stuff and cut it at extremely low speeds to avoid a stray spark causing a fire), than because it's radioactive.

[TheNephew]

If memory serves [since I was last on Wikipedia...] depleted uranium gives out about half the radiation that raw stuff of similar mass/size etc. does - so it's still pretty nasty.
As far as toxicity goes, I'd have assumed it was toxic in the way most heavy metals are - so as long as you don't spend too much time breathing dust [that being more an issue when crafting rather than using it] in or licking it, it shouldn't be a huge issue. [Or ritually stroking the surface reverentially for hours a day, I guess..]
I guess I'd have to agree that it's probably a heavy metal alloy. I was initially unconvinced due to some of the more insane sounding properties of adamantium, but then I'm not all that well educated on the properties of tailored heavy metal alloys either, so I've no reference point really.

[N01H3r3]

If memory serves [since I was last on Wikipedia...] depleted uranium gives out about half the radiation that raw stuff of similar mass/size etc. does - so it's still pretty nasty.

Oddly, not as much as you'd think. Due to its composition, most of the radiation that DU does put out is alpha, which is essentially harmless to humans so long as it stays outside the body, given that it can't get through human skin, paper, and similarly thin materials and only travels a short distance (it's extremely dangerous once it gets in, however, for much the same reason - it can't get through your skin, so it bounces around your insides. It's the type of radiation that killed Alexander Litvinenko back in 2006).

That's not to say that it's not dangerous, but between the quantity of radiation (about 60% of natural Uranium) and the type (alpha being easy enough to deal with in controlled conditions, compared to beta or gamma), it's relatively low-risk as radioactive metals go.

Trust me on this. I'd get more of a dose on a week's holiday in Cornwall than I would from spending a week at work dealing with DU. Though that's probably more because the ground in Cornwall produces a lot of Radon gas.

[TheNephew]

I'd get more of a dose on a week's holiday in Cornwall than I would from spending a week at work dealing with DU. Though that's probably more because the ground in Cornwall produces a lot of Radon gas.

Yup - stay out of the basement and you'll be fine though.

I can't help but think that this has got a little sidetracked though.