An update to the ceramic nozzle blog post:
Altitude compensation attachments for standard rocket engines, and
applications, Page 6: space shuttle tiles and other ceramics for nozzles.
UPDATED: 3/6/2018
https://exoscientist.blogspot.com/2017/12/altitude-compensation-attachments-for.html
Ceramics are now being studied for nozzles and other engine components for
jet engines:
Ceramic matrix composites: Hot engine solution.
Disruptive designs for composites operation in 1093°C zones.
Article Post: 4/11/2017
DONNA DAWSON
https://www.compositesworld.com/articles/ceramic-matrix-composites-hot-engine-solution
Rocket engines seem to be lagging behind in this regard.
These ceramics may weigh only 1/3rd the weight of the metal components.
Imagine a standard kerosene engine T/W ratio being raised to over 300 to 1,
or the already high T/W Merlin engine being raised to over 500 to 1(!).
The lightweight ceramics now being studied for the jet engine applications
would still need regenerative cooling channels in rocket engines for them
to operate. This is because the combustion temperatures in rocket engines
would still be above the melting point of these ceramics. However, this is
known to reduce the operational lifetime of the engines.
But suppose we had a ceramic that had a melting point even higher than the
combustion temperatures? Then regenerative cooling would not be needed and
then like jet engines, rocket engines could operate for thousands of hours,
giving rockets reusability comparable to jet aircraft.
We may have now such a ultra high temperature ceramic:
Rediscovered ceramic Hafnium Carbide can withstand temperatures three times
hotter than lava at 4050 celsius and could help enable hypersonic planes.
brian wang | September 17, 2014
https://www.nextbigfuture.com/2014/09/rediscovered-ceramic-hafnium-carbine.html
Bob Clark
On Thu, Dec 28, 2017 at 3:48 PM, Robert Clark <rgregoryclark@xxxxxxxxx>
wrote:
Could the famous space shuttle tiles be used for nozzle material?
Another possibility is the ceramic material developed by aerospace engineer
GW Johnson. A big advantage of the Johnson ceramic is it can be homemade
from commercially available materials, quite useful for the amateur rockets.
Altitude compensation attachments for standard rocket engines, and
applications, Page 6: space shuttle tiles and other ceramics for nozzles.
https://exoscientist.blogspot.com/2017/12/altitude-
compensation-attachments-for.html
Bob Clark
On Tue, Oct 3, 2017 at 5:07 AM, Robert Clark <rgregoryclark@xxxxxxxxx>
wrote:
I've been been investigating ceramic nozzles also, for lightweighting
purposes. Long, vacuum-optimized nozzles take up a significant part of the
dry mass of an upper stage solid motor.
Some references I've found:
The next generation of ceramic matrix composites.
New developments in the search for higher-temperature and more
damage-tolerant CMCs.
Ginger Gardiner
Blog Post: 4/11/2017
https://www.compositesworld.com/blog/post/the-next-generatio
n-of-ceramic-matrix-composites
Integrated Ceramic Matrix Composite-Carbon/Carbon Structures for Large
Rocket Engine Nozzles and Nozzle Extensions.
The material system could be used in rocket propulsion components in
which temperature, environmental reactivity, and economy are increasingly
demanding.
Marshall Space Flight Center, Alabama
Friday, 01 July 2016
http://www.techbriefs.com/component/content/article/ntb/tech
-briefs/materials/24963
Ceramic matrix composites make inroads in aerospace
Published on May 14th, 2013 | By: Jim Destefani
http://ceramics.org/ceramic-tech-today/ceramic-matrix-compos
ites-make-inroads-in-aerospace
Advanced structural ceramics in aerospace propulsion.
Nitin P. Padture
Nature Materials 15, 804–809 (2016) doi:10.1038/nmat4687
Published online 22 July 2016
http://www.nature.com/nmat/journal/v15/n8/full/nmat4687.html
Ceramic Materials for Reusable Liquid Fueled Rocket Engine Combustion
Device.
http://rocket-propulsion.info/resources/articles/Ceramic_Mat
erials_For_LPRE.pdf
Some of these such as by GE may be proprietary but you may be able to
get info on their composition from patent applications.
Another possibility is the ceramic material investigated years ago by
retired aerospace engineer G.W. Johnson for ramjet programs he worked on:
Reusable Ceramic Heat Shields - GW Johnson - 16th Mars Society Convention.
http://www.youtube.com/watch?v=3MXYY3jnNr0
In regards to making ceramics more crack resistant, perhaps we could do
something long done in construction to make concrete more crack resistant,
addition of steel reinforcement bars, rebars, at regular intervals in the
concrete. In our case for lightweighting reasons, we might want to use more
lightweight materials than steel, such as carbon fiber for example.
BTW, instead of machining the graphite or ceramic you might also try
3D-printing.
Bob Clark
On Tue, Oct 3, 2017 at 2:06 AM, Brett Coles <brettcoles@xxxxxxxxx> wrote:
Hi all!
I am wanting to investigate some different types of nozzles for solid
motors. We usually use graphite. It takes the heat and thermal shock well,
but is quite soft. If we are using a propellant with high solids,
especially a lot of metal, it makes the nozzle a one-time-use part. Since
the machine shop at my university isn't super enthusiastic about me
machining graphite all the time and I would like to make a lot of nozzles
for a characterizer, I am thinking about using some kind of ceramic since
that would be harder than graphite. I think if I used some kind of high
temperature ceramic, it would crack due to thermal shock. Additionally, I
am thinking I will have to sinter whatever oxide I use in order to get the
requisite hardness. I do have access to a kiln, but I don't think it will
get anywhere near the sintering temperature for Magnesium Oxide.
Basically, I have the following requirements:
1. The nozzle material must be heat resistant. (This rules out most
metals, and a good deal of oxides.) A question I have is how thermally
resistant the substance needs to be. Does it have to approach graphite?
2. The nozzle material must be hard to resist abrasion by hypersonic
aluminum oxide particles.
3. The nozzle material must be resistant enough to thermal shock
that it does not crack at ignition, during burn, or as it is cooling
down.
The question I have with this is if this can be mitigated by adding a
conductive material to the ceramic mix. My understanding of failure due
to
thermal shock is that the material fails because of different expansion
in
hot vs cold spots. If the material is more conductive, there will be less
of a thermal gradient.
Sorry that was long, and I'm not sure if it made sense. I'm sure I'll
explain more as I get answers.
Thanks in advance! --
Brett
