I know of one manufacturer that uses dry N2 to remove the NH3 from the
reaction of AP/HX878.
On Thursday, July 11, 2019, 5:33:17 PM EDT, George Herbert
<george.herbert@xxxxxxxxx> wrote:
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;
processing usually
proceeds by mixing the liquids (including catalyst), adding the aluminum
to the liquid mix w/ careful hand stirring), then folding into the AP
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 the
> 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
