Often for lost wax foundry work, they use sodium silicate based ceramics IIRC –
not too dissimilar to the muffler putties I mentioned in my prev post. Very
fragile, especially upon high temp exposure, but I suppose with enough
structural glass/carbon fibre support, it could be made to work.
Troy
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On ;
Behalf Of John Dom
Sent: Thursday, 22 April 2021 9:26 PM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: nozzle problem - problem nozzle...
In juwelry manufacture (going fo the lost wax technique) quartz plaster is used
as a robust casting mould for say, pouring liquid gold or platinum in. Maybe
google for jewelry manufacture tools.
John Dom
From: arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx>
[mailto:arocket-bounce@xxxxxxxxxxxxx] On Behalf Of tom@xxxxxxxxxxxxxxx ;
<mailto:tom@xxxxxxxxxxxxxxx>
Sent: donderdag 22 april 2021 12:31
To: arocket@xxxxxxxxxxxxx <mailto:arocket@xxxxxxxxxxxxx>
Subject: [AR] Re: nozzle problem - problem nozzle...
I'm afraid there will be no epoxy resin durable enough to withstand these
tempereatures. Most epoxy resins decompose around 120 °c with every few
withstanding 200-250 °C. One could use phenolic resins I suppose, at least
Aerotech has successfully flown their O motor recentlyx without significat
nozzel erosion...
Other than that: with an O motor, is 50g-100g more weight at the nozzle an
issue ;) ?
Cheers,
Tom
Am 2021-04-22 09:16, schrieb Hagen Hübner:
Hello everyone,
a few days ago we (Forschungsgemeinschaft Alternative Raumfahrt - FAR e.V.)
tested an O-motor with a nitrate-based fuel. The part of the nozzle near the
combustion chamber was made of graphite and withstood the high temperatures and
the abrasive exhaust without any problems. The nozzle extension - for weight
reasons made of carbon fiber reinforced epoxy resin (tempered, but otherwise
standard resin), material thickness 3 - 7 mm - however, failed after about one
second of burning time (see attached photos).
Question(s): What can be improved to prevent the extension from burning through
in the future? Is there any chance at all chance to make a weight-saving nozzle
extension made of composite, designed for a burn time of 5 - 10 seconds? Which
more temperature-resistant resin should I use? Which reinforcing fibers are
(more) useful? Do basalt fibers have a significant advantage over carbon fibers?
Regards,
Hagen