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Q Carbon -- Harder Than Diamond


TTK Ciar
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Just saw this, and my first thought was, "What would be the mass efficiency of a metal/ceramic composite incorporating q-carbon?":

 

http://phys.org/news/2015-11-phase-carbon-diamond-room-temperature.html

 

Second thought was, "Hey this doesn't look like it would be too hard to mass-produce".

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Just saw this, and my first thought was, "What would be the mass efficiency of a metal/ceramic composite incorporating q-carbon?":

 

http://phys.org/news/2015-11-phase-carbon-diamond-room-temperature.html

 

Second thought was, "Hey this doesn't look like it would be too hard to mass-produce".

"Hold my beer and watch this..."

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Ceramic is used for its high hardness to achieve specific effects. It doesn't absorb significant energy, but it does deform penetrators, sometimes extremely (qv interface defeat). None of the ceramics typically used in armor are particularly tough. De Beers developed Syndie armor, which is synthetic diamonds cast in steel and has a fantastic mass and thickness efficiency.

 

 

http://ciar.org/ttk/mbt/papers/papers.2007-12-21/armor.x.ijie.vol24pp259_275.impact_of_metallic_projectiles_on_ceramic_targets_transition_between_interface_defeat_and_penetration.lundberg_renstrom_lundberg.2000.pdf

Edited by TTK Ciar
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I was wondering about the armour applications of diamonds and thought it was a silly idea. Didn't know De Beers developed something like that. Amazing. My net access now is crap so can't download the PDF. Is it diamond dust or something larger mixed with the steel?

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“In Lower Pomerania is the Diamond Mountain, which is two miles and a half high, two miles and a half wide, and two miles and a half in depth; every hundred years a little bird comes and sharpens its beak on it, and when the whole mountain is worn away by this, then the first second of eternity will be over.”

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Ceramic is used for its high hardness to achieve specific effects. It doesn't absorb significant energy, but it does deform penetrators, sometimes extremely (qv interface defeat). None of the ceramics typically used in armor are particularly tough. De Beers developed Syndie armor, which is synthetic diamonds cast in steel and has a fantastic mass and thickness efficiency.

 

 

 

 

The price quoted above is extremely high, highly pure material or balistic grade or what?

 

Aluminum oxide, isn't it Al2O3? 60$/lb?

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The prices are for large sintered shapes, and are some years old so might need updating. Unsinstered granules are of course orders of magnitude cheaper, which is part of the appeal of cermets and PCCs.

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Guest Jason L

The prices are for large sintered shapes, and are some years old so might need updating. Unsinstered granules are of course orders of magnitude cheaper, which is part of the appeal of cermets and PCCs.

 

Cermets suck.

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Ceramic is used for its high hardness to achieve specific effects. It doesn't absorb significant energy, but it does deform penetrators, sometimes extremely (qv interface defeat). None of the ceramics typically used in armor are particularly tough. De Beers developed Syndie armor, which is synthetic diamonds cast in steel and has a fantastic mass and thickness efficiency.

 

 

 

 

The price quoted above is extremely high, highly pure material or balistic grade or what?

 

Aluminum oxide, isn't it Al2O3? 60$/lb?

 

 

yes, it's Al2O3. the same stuff rubies and sapphires are made of.

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A sampling of sintered aluminum oxide rods from alibaba shows they've come down in price, to about $25/lb - $40/lb for the high purity stuff and about $4/lb - $5/lb for low purity. Unsintered granules appear to have come up slightly, to about $1.50/lb (used to be less than $1/lb).

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What made sintered alumina so costly? Energy consumption? Low volume demand on market?

 

Aluminum consumes large energy because it is an active element, but bulk price is low.

 

If hardness is desired, isnt't it glass (sillica) quite hard, cheap, and easy to form to any shape?

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What made sintered alumina so costly? Energy consumption? Low volume demand on market?

Specialized equipment is required to compress ceramic granules under very high pressure while they are heated and/or subjected to high electric current. They must be held under pressure for some time to ensure good bonding and uniform consistency. Afterwards, if the application demands zero internal defects, pieces must be inspected via X-ray or ultrasound, and flawed pieces discarded. All of these things means the production rate for manufacturing sintered solids is low. When there is high demand (such as for silicon carbide SAPI plates), a company like Ceradyne will tool up for mass production, but then other considerations can push prices up (like big fat government contracts).

 

If hardness is desired, isnt't it glass (sillica) quite hard, cheap, and easy to form to any shape?

Compared to technical ceramics, glass is soft and spongy. See the physical characteristics of impact-resistant glass on Materialweb: http://matweb.com/search/DataSheet.aspx?MatGUID=7e5e8f5aae28433ea61febe328a9efde

 

That has a compressive strength of only 50000 psi, six to thirteen times weaker than the technical ceramics in the table previously posted. It also has a much lower fracture toughness. No Vickers Hardness rating for that product, but another glass -- http://matweb.com/search/DataSheet.aspx?MatGUID=32b4e82b743d4e0a90f41f09c083199c-- shows a Vickers of only 205, again several times lower than technical ceramics.

 

Sometimes bulletproof glass windows will incorporate a tempered glass layer between polycarbonate layers, because even though its mass efficiency is lower than polycarbonate it has a higher thickness efficiency and there are often practical limits on how thick a window may be. Also, even though glass isn't particularly hard, it is much harder than polycarbonate, so will deform a bullet's nose some, rendering it less capable of penetrating the thick polycarbonate backing layer. The front layer will be thin, providing only containment for the glass, keeping it trapped in front of the bullet rather than ejecting. qv: http://ciar.org/ttk/mbt/papers/symp_19/TB491431.pdf

 

Does anyone have price of other ballistic material for comparision, i.e RHA, HHS,...?

Fully MIL-A-12560 compliant steel plate tends to be a bit pricey for purely artificial reasons, but laboratories will often use SAE 4340 steel hardened to 350 BHN as an inexpensive substitute, and it is comparable enough to the steels used for armor in other countries. Hardened 4340 in thick plates tends to run about $0.75 to $0.85 per pound (USD).

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