The Military Wants Ceramic Submarine Hulls

[kernals12]

Believe it or not, ceramics, as a class of materials, are stronger than metals, in addition to being able to withstand extreme temperatures, resist corrosion, and be easily molded into arbitrary shapes. But as we all know, ceramics are very brittle. But the geniuses at DARPA think that this problem can be solved and have put out a contract for it. Their interest in it is for "airframes, turbine disks, ground vehicle chassis, or submarine hulls.". But the civilian uses would have an impact rivalling that of DARPA's most famous invention; the internet.

[Road Hog]

DARPA would be better off pursuing artificial diamond materials. Hardest material known to man, its manufacture is already longstanding & the carbon use would help the ecology.

[kernals12]

DARPA would be better off pursuing artificial diamond materials. Hardest material known to man, its manufacture is already longstanding & the carbon use would help the ecology.

Diamonds would need to be cut in cost by several orders of magnitude before they could be used to build submarines.

Ceramics otoh are already very cheap.

[Road Hog]

DARPA would be better off pursuing artificial diamond materials. Hardest material known to man, its manufacture is already longstanding & the carbon use would help the ecology.

Diamonds would need to be cut in cost by several orders of magnitude before they could be used to build submarines.

Ceramics otoh are already very cheap.

Economy of scale.

[kernals12]

DARPA would be better off pursuing artificial diamond materials. Hardest material known to man, its manufacture is already longstanding & the carbon use would help the ecology.

Diamonds would need to be cut in cost by several orders of magnitude before they could be used to build submarines.

Ceramics otoh are already very cheap.

Economy of scale.

Artificial diamonds are already mass produced. It takes 2 weeks under extremely high pressure under current processes, which is expensive. And even if that wasn't an issue, diamonds are very difficult to work with and they are quite fragile. Not very desirable for making a submarine hull.

[hotdogPi]

You only need 24 diamonds for a full suit of armor.

[02 Park Ave]

What is wrong with HY-80?  It's weldable.  Are ceramics?  What is the strength to weight ratio of ceramics anyway?

[kernals12]

What is wrong with HY-80?  It's weldable.  Are ceramics?  What is the strength to weight ratio of ceramics anyway?

Very, very high

http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts/spec-spec/NS6Chart.html

[kernals12]

You only need 24 diamonds for a full suit of armor.

I assume this is a video game joke?

[Max Rockatansky]

You only need 24 diamonds for a full suit of armor.

I assume this is a video game joke?

Apparently a Minecraft reference:

https://stealthygaming.com/diamonds-for-full-armor-tools/

[hotdogPi]

I'm pretty sure that webpage is AI-generated. Some of the numbers are wrong (as well as the claim that boots aren't part of a full suit).

[Max Rockatansky]

I'm pretty sure that webpage is AI-generated. Some of the numbers are wrong (as well as the claim that boots aren't part of a full suit).

I wouldn't know given I've never played Minecraft.  I just took your quote and got that result in a search engine.

[kernals12]

It's really too bad they couldn't have succeeded in this 20 years ago. If they had, we'd all be driving turbine powered cars by now.

[Max Rockatansky]

What correlation is there between ceramic hulls and automotive turbine engine development?  It isn't as though the turbine didn't get the old college try by auto manufacturers. 

[kalvado]

What correlation is there between ceramic hulls and automotive turbine engine development?  It isn't as though the turbine didn't get the old college try by auto manufacturers. 

probably the idea that technologies, including advanced materials, tend to trickle down from most demanding applications to more mundane.
composites may be a good example, which is still making its way into the general car market

[kernals12]

What correlation is there between ceramic hulls and automotive turbine engine development?  It isn't as though the turbine didn't get the old college try by auto manufacturers. 

It's actually very interesting. Kerosene burns at about 3500 degrees fahrenheit, gasoline slightly more. Such heat will easily melt all but the most exotic metals. That's not a problem for piston engines because combustion is intermittent and it's easy to provide external cooling. Turbine engines don't have the same luxury, as combustion is continuous and the turbine blades are always going to be exposed to the heat. Engineers can only fix that problem by running the engines with lots of excess air. That keeps the engine from being destroyed, but it also hurts fuel economy because you need a bigger compressor to get the same amount of output.

Beginning in the late 60s, engineers looked at ceramics for the solution. They can handle much higher temperatures than metals (and they're also cheaper and lighter). If they could just get over ceramics' brittleness, they could make turbine engine more efficient than a diesel. But that never happened.

[Max Rockatansky]

What correlation is there between ceramic hulls and automotive turbine engine development?  It isn't as though the turbine didn't get the old college try by auto manufacturers. 

It's actually very interesting. Kerosene burns at about 3500 degrees fahrenheit, gasoline slightly more. Such heat will easily melt all but the most exotic metals. That's not a problem for piston engines because combustion is intermittent and it's easy to provide external cooling. Turbine engines don't have the same luxury, as combustion is continuous and the turbine blades are always going to be exposed to the heat. Engineers can only fix that problem by running the engines with lots of excess air. That keeps the engine from being destroyed, but it also hurts fuel economy because you need a bigger compressor to get the same amount of output.

Beginning in the late 60s, engineers looked at ceramics for the solution. They can handle much higher temperatures than metals (and they're also cheaper and lighter). If they could just get over ceramics' brittleness, they could make turbine engine more efficient than a diesel. But that never happened.

Still have to exhaust that heat somewhere.  That was a major issue with the turbine car concepts, stepping behind the exhaust could lead to a bad time. 

[Max Rockatansky]

What correlation is there between ceramic hulls and automotive turbine engine development?  It isn't as though the turbine didn't get the old college try by auto manufacturers. 

probably the idea that technologies, including advanced materials, tend to trickle down from most demanding applications to more mundane.
composites may be a good example, which is still making its way into the general car market

Fair enough, but composite materials don't necessarily solve the issues of packaging a powertrain (as noted in the above comment).  Even the early nuclear car concepts never really got off the drawing board because there was no way to solve the exhaust issues.

[kernals12]

What correlation is there between ceramic hulls and automotive turbine engine development?  It isn't as though the turbine didn't get the old college try by auto manufacturers. 

It's actually very interesting. Kerosene burns at about 3500 degrees fahrenheit, gasoline slightly more. Such heat will easily melt all but the most exotic metals. That's not a problem for piston engines because combustion is intermittent and it's easy to provide external cooling. Turbine engines don't have the same luxury, as combustion is continuous and the turbine blades are always going to be exposed to the heat. Engineers can only fix that problem by running the engines with lots of excess air. That keeps the engine from being destroyed, but it also hurts fuel economy because you need a bigger compressor to get the same amount of output.

Beginning in the late 60s, engineers looked at ceramics for the solution. They can handle much higher temperatures than metals (and they're also cheaper and lighter). If they could just get over ceramics' brittleness, they could make turbine engine more efficient than a diesel. But that never happened.

Still have to exhaust that heat somewhere.  That was a major issue with the turbine car concepts, stepping behind the exhaust could lead to a bad time. 

That is exactly the opposite of the truth. Thanks to the use of a regenerator, Chrysler was able to get exhaust temperatures *lower* than that of a piston engine.

[kernals12]

What correlation is there between ceramic hulls and automotive turbine engine development?  It isn't as though the turbine didn't get the old college try by auto manufacturers. 

probably the idea that technologies, including advanced materials, tend to trickle down from most demanding applications to more mundane.
composites may be a good example, which is still making its way into the general car market

Fair enough, but composite materials don't necessarily solve the issues of packaging a powertrain (as noted in the above comment).  Even the early nuclear car concepts never really got off the drawing board because there was no way to solve the exhaust issues.

Nuclear car concepts? Is that a typo?

[Max Rockatansky]

What correlation is there between ceramic hulls and automotive turbine engine development?  It isn't as though the turbine didn't get the old college try by auto manufacturers. 

probably the idea that technologies, including advanced materials, tend to trickle down from most demanding applications to more mundane.
composites may be a good example, which is still making its way into the general car market

Fair enough, but composite materials don't necessarily solve the issues of packaging a powertrain (as noted in the above comment).  Even the early nuclear car concepts never really got off the drawing board because there was no way to solve the exhaust issues.

Nuclear car concepts? Is that a typo?

No, this was a thing Ford did some work on.  The concept was called the Nucleon and never was more than something that existed on paper.

[kernals12]

With this program, DARPA could send us into the stone age.

[sglaughlin]

There is a series of sci-fi military adventure books about a near future war between the US, UK and others and a German/South African alliance.  The main players in these books are a US submarine with ceramic hull (50kt top speed, dive to 5,000 feet shooting all sorts of high power conventual and nuclear torpedoes.  The other side also has a couple of these.  See:

https://www.goodreads.com/series/85465-jeffrey-fuller

[kernals12]

I'm imagining ceramic bridges. They could be made from panels fabricated off-site, trucked in, and then bolted together using far less material and labor than ones made from reinforced concrete. They'd also be largely immune to corrosion and thermal expansion.

[GaryV]

Chrysler was able

What Chrysler vehicle used a turbine? A vehicle that was older than most members on this board. In a half-century since, there hasn't been improvements that could cause such a thing to become viable. Chrysler stopped development because of emissions and poor fuel economy. So what would a turbine contribute today?