Unrealistic SCI-FI metals

Guardsman Bass · Post by **Guardsman Bass** » 2002-12-27 03:12pm

Out of curiousity to anyone out there with knowledge on materials science, could you in any way create materials that could take heavy amounts of energy in the form of heat and/or physical damage from particle impact and still maintain its solid form any where near that which some materials(such as Durasteel in SW) in sci-fi can? Note: I am just stating materials: not specifically metals; it could be any thing that is in solid or possibly crystalline form.

kojikun · Post by **kojikun** » 2002-12-27 03:33pm

well .. with sufficiently advanced technology, yes. But it doesnt have to be metal. Or it doesnt need to be exposed such that it would be in danger of impact. for instance, the spaceshuttle can deorbit and reenter the atmosphere with its leading edge heating up to something near 2000 +degrees celsius. This would melt the shuttle if the tiles werent there, because the metal the shuttles made of cant withstand those temperatures.

SyntaxVorlon · Post by **SyntaxVorlon** » 2002-12-27 03:51pm

The big thing they use for armor in scifi these days is high heat resistant ceramics, ceramics, especially silicon enhanced, are very heat resistant. Also crystalline armor, cerca Victory Class Destroyer in B5.

Post by **Darth Wong** » 2002-12-27 04:03pm

Ceramics are brittle, and even transformation-toughened ceramics are still nowhere near as tough as steel. Moreover, their strength is heavily dependent upon load direction (they're not as strong in tension as they are in compression).

Steel is a beautiful metal because:

Strength is independent of loading direction.
Fatigue cycling limit means that below critical point, it can take a virtually infinite number of load cycles without fatigue failure (unlike aluminum).
It is very easily alloyed for a very wide range of properties.
Its strength properties are very easy to manipulate through heat treatment.
It is highly weldable.
It is plentiful (nearly 80% of the Earth's mass is iron).
It is extremely stable (very difficult to make it burn like aluminum, magnesium, etc).

And these are the reasons why we love steel. No other material exhibits all of these properties; there are materials which are light and stiff, but extremely difficult to form and weld and prone to brittle failure, there are materials which have excellent tensile strength but no rigidity (eg- carbon nanotubes), there are materials which have superb compressive strength but no tensile strength or toughness (eg- ceramics), etc.

As for the original question, no. The strength of SW materials is ridiculously high and entirely unrealistic. To build a 17km long ship and accelerate it at 3000 G's without massive deformation is simply not possible using any remotely feasible materials. We could muse that the SW galaxy has found some way to create entirely artificial atomic structures by manipulating subatomic particles, but if we're going to ask what we can realistically achieve, we can say with a high degree of certainty that we will never achieve that. We are talking about needing materials which are a thousand times stronger than anything we have.

And now, a parting word:

Rudyard Kipling wrote:Gold is for the mistress - silver for the maid,
Copper for the craftsman cunning in his trade.
"Good!" said the Baron, sitting in his hall,
But steel, cold steel, is master of them all!

Cpt_Frank · Post by **Cpt_Frank** » 2002-12-27 04:12pm

All hail steel!

SyntaxVorlon · Post by **SyntaxVorlon** » 2002-12-27 04:30pm

Steel melts on first plasma volley, and with a thick ceramic exterior a craft can take several plasma/ radiation volleys. Wong I'm sorry to burst your bubble but we're talking about heat resistance here. If memory serves the WTC buildings had steel superstructures but because of the heat from the jet fuel fires lost all of its ability for load bearing, and crumpled. However if one was able to make a strong enogh ceramic the shielding could take a heavy impact.
If you were building a combat craft the superstructure would be steel but, assuming energy weapons are in high usage, the hull would be pure ceramics.
You can get into a ceramic boat and ride out a lava flow. A steel boat would melt. The reason being that most metals have extemely low heat absorbancy rates. In other words they conduct heat well, so anything made of steel or any metal will heat up very fast and loose its support capabilities. So if you shot a plasma volley with a high density rail gun volley right behind it, a steel hull will be ruptured.
The ceramics would be for the hull, the steel would be protected from heat beams, plasma weapons and nuclear weapon volleys, and the ship would retain its tensile strength.

Post by **Darth Wong** » 2002-12-27 04:35pm

SyntaxVorlon wrote:Steel melts on first plasma volley, and with a thick ceramic exterior a craft can take several plasma/ radiation volleys. Wong I'm sorry to burst your bubble but we're talking about heat resistance here.

Ceramics are very good at heat resistance, it's true. But they shatter, which is why they must be laminated in steel to be useful in armour. A concentrated hit would shatter ceramic armour from the resultant stresses.

If memory serves the WTC buildings had steel superstructures but because of the heat from the jet fuel fires lost all of its ability for load bearing, and crumpled. However if one was able to make a strong enogh ceramic the shielding could take a heavy impact.

If the WTC buildings replaced their steel girders with ceramic, they would never have stood in the first place.

If you were building a combat craft the superstructure would be steel but, assuming energy weapons are in high usage, the hull would be pure ceramics.

Then the hull would shatter at the first hit.

You can get into a ceramic boat and ride out a lava flow. A steel boat would melt. The reason being that most metals have extemely low heat absorbancy rates. In other words they conduct heat well, so anything made of steel or any metal will heat up very fast and loose its support capabilities. So if you shot a plasma volley with a high density rail gun volley right behind it, a steel hull will be ruptured.

And if you shoot a high density rail gun volley at a ceramic, it will shatter with or without the prior laser (a plasma volley would realistically just spread out into a harmless cloud before it reaches the target).

The ceramics would be for the hull, the steel would be protected from heat beams, plasma weapons and nuclear weapon volleys, and the ship would retain its tensile strength.

Actually, the ideal hull would be superconductive layering outside a steel superstructure. Ceramic conducts heat very poorly, and its only worthwhile attribute is a high melting point, which helps it survive immersion in molten fluids below its own melting point, but which would be useless against something like a laser. That's why a laser will blast through brick as easily as it blasts through metal, and with more violent shattering/failure effects.

Post by **NecronLord** » 2002-12-27 04:44pm

Lord Wong wrote:Actually, the ideal hull would be superconductive layering outside a steel superstructure. Ceramic conducts heat very poorly, and its only worthwhile attribute is a high melting point, which helps it survive immersion in molten fluids below its own melting point, but which would be useless against something like a laser. That's why a laser will blast through brick as easily as it blasts through metal, and with more violent shattering/failure effects.

Oddly enough my universe uses that system. With some Ablative armour on top. Oh and sometimes a stealth layer.

Andrew J. · Post by **Andrew J.** » 2002-12-27 04:47pm

How does steel compare to titanium?

Post by **Darth Wong** » 2002-12-27 05:06pm

Titanium is strong and light (a heat-treated titanium alloy is not as strong as a heat-treated tool steel, but it's a fair bit lighter). However, it's a pain in the ass to work with, and it's expensive as hell. It is used primarily for corrosion resistance and high-temperature creep-resistant applications. However, titanium has an HCP lattice structure and is inherently less ductile than steel as a result.

Patrick Degan · Post by **Patrick Degan** » 2002-12-27 05:17pm

Darth Wong wrote:Steel is a beautiful metal because:

Strength is independent of loading direction.

Fatigue cycling limit means that below critical point, it can take a virtually infinite number of load cycles without fatigue failure (unlike aluminum).

It is very easily alloyed for a very wide range of properties.

Its strength properties are very easy to manipulate through heat treatment.

It is highly weldable.

It is plentiful (nearly 80% of the Earth's mass is iron).

It is extremely stable (very difficult to make it burn like aluminum, magnesium, etc).
And now, a parting word:
Rudyard Kipling wrote:Gold is for the mistress - silver for the maid,
Copper for the craftsman cunning in his trade.
"Good!" said the Baron, sitting in his hall,
But steel, cold steel, is master of them all!

And thus is answered:

THE RIDDLE OF STEEL

aerius · Post by **aerius** » 2002-12-27 05:29pm

Every time someone brings up the joys of titanium, carbon fibers and ceramics I feel like going on a rant. First off, titanium is not stronger than steel, if I had a nickel for every time someone says it is I wouldn't need a job. Tensile strength for Ti tops out at around 1400 MPa, and these high strength Ti alloys are next to impossible to weld. A high strength steel like Aermet 100 has a UTS of around 2000 MPa, and can be easily welded with a basic TIG welder. On top of that steel is a lot harder than titanium and can absorb a much greater impact without damage.

A tube made of Aermet 100 thats 28mm in diameter with 0.5mm thick walls can be bashed against concrete floors, edges, and corners without getting dented, and it'll take chips out of the concrete. Do this to a titanium tube of the same dimensions and it'll dent, crack, & bend in half after a few hits. I verified this first hand about 10 years ago at a bike show where they were demonstrating the properties of various tubing materials used in bicycles. Aluminum tubes folded in half on the first hit, while carbon fiber ones shattered on impact. This is not the kind of stuff you want happening to your armor or spaceship.

What makes steel such a wonderful material is its combination of strength, hardness, and toughness. It's pretty strong so it ain't gonna pull apart, hard so it ain't gonna get holes punched through it, and tough meaning it isn't gonna shatter like glass when it gets hit. Other materials may be better than steel in one or maybe 2 of these properties, but will be sadly lacking in the other properties. For instance, take monocrystalline silicon, the same stuff used in microchips. It has twice the strength of steel and a similar hardness, but it'll shatter like glass.

With materials it's almost always a trade-off, you don't get stuff for free.

Arthur_Tuxedo · Post by **Arthur_Tuxedo** » 2002-12-27 05:41pm

How about plain old iron?

Warspite · Post by **Warspite** » 2002-12-27 05:45pm

Arthur_Tuxedo wrote:How about plain old iron?

Steel is a combination of iron with certain elements, mainly carbon. Iron, as is, is inferior to steel.

Post by **Darth Wong** » 2002-12-27 05:50pm

Actually, cast iron has carbon in it too. Cast irons and all steels fall into the category of "ferrous alloys", since pure iron is not used for anything (pure metals are usually useless).

If you want to get technical, cast iron is defined as an iron-carbon-silicon alloy which passes through a eutectic reaction during the solidifcation process.

Warspite · Post by **Warspite** » 2002-12-27 05:57pm

Darth Wong wrote:Actually, cast iron has carbon in it too. Cast irons and all steels fall into the category of "ferrous alloys", since pure iron is not used for anything (pure metals are usually useless).

If you want to get technical, cast iron is defined as an iron-carbon-silicon alloy which passes through a eutectic reaction during the solidifcation process.

Talked like a true professional...

Wicked Pilot · Post by **Wicked Pilot** » 2002-12-27 06:56pm

All these big science words are making me feel inadequate.

I wish I was an engineer.

Warspite · Post by **Warspite** » 2002-12-27 07:05pm

Wicked Pilot wrote:All these big science words are making me feel inadequate.

I wish I was an engineer.

There's no need to go that much, any good technical library can have books with these big (non-technobabble) words. But, yeah, engineering is FUN!

Post by **Colonel Olrik** » 2002-12-27 07:10pm

Wicked Pilot wrote:All these big science words are making me feel inadequate.

I wish I was an engineer.

Buah ah ah! You wish you knew the difference between martensitic, ferritic and austenitic steel, between granular and grey molten iron, Why is dura-aluminium the way to go and what the fuck is a CK45 quality tempered carbon steel?

I'm not telling!

Blah!

aerius · Post by **aerius** » 2002-12-27 07:19pm

Wicked Pilot wrote:All these big science words are making me feel inadequate.

I wish I was an engineer.

It's not that bad yet, we have yet to discuss stress/strain curves, elongation, retained austenite in steels, fatigue & corrosion micro-fracture propagation, secondary hardening tool steels and all that other fun stuff.

Post by **Colonel Olrik** » 2002-12-27 07:26pm

Yes, I'm evil.

Einhander Sn0m4n · Post by **Einhander Sn0m4n** » 2002-12-27 07:49pm

Colonel Olrik wrote:

Yes, I'm evil.

Evil Shmevil. I've deciphered FAR worse...

Wicked Pilot · Post by **Wicked Pilot** » 2002-12-27 08:04pm

TAKE THIS ENGINEERS!

Warspite · Post by **Warspite** » 2002-12-27 08:06pm

*Sigh* There's not enough space on this board for me to post a full ship's general arrangment, or structural drawing... And believe me, those are BIG!

Enlightenment · Post by **Enlightenment** » 2002-12-27 08:21pm

SyntaxVorlon wrote:If memory serves the WTC buildings had steel superstructures but because of the heat from the jet fuel fires lost all of its ability for load bearing, and crumpled.

The three WTC buildings that collapsed were indeed brought down by heat-induced failure of the steel structure. However the heat was generated by uncontroled multi-floor contents fires rather than the jet fuel itself. The jet fuel from the Islamicised aircraft simply acted as an accelerant but did not significantly contribute to the fire temperature or heat loading on the structure.