I was thinking solubility and permeability of liquid and solidified binder
primarily, in the hope that the bubbles would come out more easily.
Hydrogen is famously permeable through many things, but I don't know for
example HTPB. I didn't find good info last time I deep dived, but that was
a few years ago.
With both, things like the surface contact angles of surface tension are
supposed to differ with gas in the environment. If some gas mixture more
efficiently wets HTPB onto AP or whatever solid oxidizer, or onto metal
powders, I'd think you might get less bubbles to start with.
With centrifugal casting, He bubbles would be more bouyant so they'd
surface faster/more easily.
All of this with the caveat that nobody seems to have specifically
researched any of these effects in references I found. The centrifugal
casting gas effect would be easy to test; inert AP simulant should have
about the same effect. Wetting, I don't know, I understand conceptually
how the testing is done but not the mechanisms and techniques.
Permeability on cured products should be easy, on liquids I don't know how
it's done.
On Thu, Jul 11, 2019 at 1:53 PM William Claybaugh <wclaybaugh2@xxxxxxxxx>
wrote:
George:
Don’t think I’d much care for trying Hydrogen but replacing air bubbles w/
He might at least add a bit of performance.
Bill
On Thu, Jul 11, 2019 at 2:43 PM George Herbert <george.herbert@xxxxxxxxx>
wrote:
Not going to guess what the results are, but i've considered the problem
of non-vacuum gas reduction before and wondered if using non-vacuum but
different environmental gas mixes might help. Ex, would doing the mixing
in a helium or hydrogen filled chamber be easier and still somewhat
effective, presuming those will have different bubble behavior.
I'm not vaguely equipped to test that right now, though.
On Thu, Jul 11, 2019 at 1:31 PM Anthony Cesaroni <anthony@xxxxxxxxxxx>
wrote:
Not with traditional solid constituents and configurations and I’ll
leave it at that.
One technique that does have some merit is centrifugal casting. In this
example you have more energy at your disposal to consolidate the solid
loading in the absence of proper vacuum processing equipment. The
propellant mix is prepared and post degassed using vacuum, turnover and
vibration as usual. The prepared propellant is then transferred into the
motor case or casting tube with a cap on one end. The case is then closed
with a cap on the remaining open end and the whole affair is spun,
longitudinally in a spin fixture or a lathe equipped with explosion proof
electrics (I’m sure). The case is spun at moderate speed until the
propellant cures.
After the propellant has cured, a section through the propellant will
show very high solid consolidation with a resin rich condition on the ID
surface. The next step is to use your explosion proof lathe to bore out the
excess resin on the ID and you will have an extraordinarily high solids
loaded propellant grain remaining. Some experimentation is required to
optimize the particle morphology and the speed should be optimized to
produce the most consolidation while minimizing the migration of the
smaller diameter particles.
To optimize the process further, one end of the case should be supported
by a roller steady and the dam on that end should have an opening to allow
the slow and well placed transfer of the propellant into the case while
it’s spinning instead of putting the whole mess in there at the beginning.
This actually works and you can achieve some impressive densities using
this method.
Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto
*From:* arocket-bounce@xxxxxxxxxxxxx <arocket-bounce@xxxxxxxxxxxxx> *On
Behalf Of *Edward Wranosky
*Sent:* Thursday, July 11, 2019 3:43 PM
*To:* arocket@xxxxxxxxxxxxx
*Subject:* [AR] Re: Vacuum processing of solid propellant
Is there any sort of VARTM like process for manufacturing propellant?
Edward
On Mon, Jul 8, 2019 at 8:39 AM William Claybaugh <wclaybaugh2@xxxxxxxxx>
wrote:
Uwe:
Yeah, as Anthony observed it is air trapped on the solids that produces
the problem.
The AP is tri-modal (200, 400, 600 micron) and mixed via a sieve
on-site, lots of opportunity for air to entrain in that process.
The Al is 5 micron and picks up air rather like a sponge. Wetting it
and degassing might help some but the subsequent final mixing w: the AP is
going to introduce air.
I’m thinking the strategy is going to be to post processing degas a set
of samples (5 minutes, 10, 15) and compare density gain per step. That
should offer a guess as to what can be achieved before the mix sets up.
Bill
On Mon, Jul 8, 2019 at 12:18 AM Uwe Klein <uwe@xxxxxxxxxxxxxxxxxxx>
wrote:
Am 07.07.2019 um 19:59 schrieb William Claybaugh:
Uwe:
For safety we can’t mix the Al & AP together;
reminds me of the special 3 outlet can used for
chemically silvering mirrors back when. :-)
Hmm.
create separate airless pastes with each component as a first step?
Delayed wetting of solids always introduces air.
processing usuallyaluminum
proceeds by mixing the liquids (including catalyst), adding the
to the liquid mix w/ careful hand stirring), then folding into the APthe
followed by final mixing.
Bill
On Sun, Jul 7, 2019 at 11:37 AM Uwe Klein <uwe@xxxxxxxxxxxxxxxxxxx
<mailto:uwe@xxxxxxxxxxxxxxxxxxx>> wrote:
Am 07.07.2019 um 18:39 schrieb William Claybaugh:
> Does degassing the liquid components before mixing help or does
> subsequent mixing just reintroduce air?
Use mixing machinery where the mixing implements don't break the
surface. i.e. avoid "whipped cream" effects.
Any fine grained solids will need degassing after they
have been immersed in but not fully wetted by fluid components.
IMU no way around it.
Mix solids superficially, evacuate, add liquids on top.
return pressure to normal.
Then start mixing ( top mentioned prerequisites apply :-)
Uwe
--
-george william herbert
george.herbert@xxxxxxxxx
