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Product Name: Ultrahigh Temperature Materials and Components
Product Description
 Work is currently under development on ultrahigh temperature materials for
space and aerospace applications. This research is focused on the use of
ultrahigh temperature materials at temperature ranges beyond that encountered in
today\'s state-of-the-art systems.
Potential Applications
These advanced materials will be used to increase the performance of aerospace
and space engines or space based power generating systems. Such improvements
would be in the form of faster and more efficient jet airplanes for civilian and
military applications. Advances in materials would also make possible and
increase interest in new missions for space exploration. The development of an
aerospace plane for service missions to the International Space Station will
require improved performance capabilities of aerospace engines and thrusters
over the current state-of-the-art. Higher temperatures allow for increased
performance from rockets that would be used for possible manned missions to the
moon and mars. Rockets that might take a crew to the moon and mars would operate
more efficiently at higher temperatures reducing the overall mission time. This
would help reduce the cost of a manned mission and reduce the risk to the
astronauts. Finally, if man is to colonize space, we will require sufficient
energy systems to operate equipment and systems necessary for maintaining
habitability. Because of restrictions on design for space applications, these
power systems would necessarily operate at higher temperatures than comparable
terrestrial power systems.
Review of Past Work
INSPI is currently investigating chromium and chromium-alloys as a candidate for
use as an ultrahigh temperature material. Chromium is a high temperature
material with a melting point of 2136 K. Other favorable characteristics include
high oxidation and creep resistance at high temperatures. However, its
brittleness at room temperature prevents it from being used in any significant
manner. A joint research effort with the Russian Scientific Institute, LUTCH,
has produced single crystals of chromium with improved ductility. Further,
alloys with certain metals such as vanadium, rhenium, titanium, and niobium have
also been shown to improve the ductility of chromium. Because of difficulties
controlling process variables in their production facilities, in particular the
uniformity of the temperature in the reaction chamber, samples could not be
obtained that were entirely mono-crystalline. Also, the distribution of the
alloying elements was not uniform over the samples. This initial investigation
provided useful experience in dealing with these difficulties and pointed to the
need for a more sophisticated apparatus with better control over process
variables.
Current Investigation
Based on this initial lead, INSPI has constructed its own production facilities
for the production of chromium and chromium alloys by chemical vapor deposition
(CVD). The demands on such a system are great because of the requirements for
high temperature and a pure/controlled environment for the reaction to take
place. A schematic of the CVD apparatus constructed is shown in Fig. 1. This
reactor and various auxiliary components have been constructed and fine tuning
of the systems is currently underway. Once this is complete, samples can be
produced for testing.
The process is illustrated in Fig. 2 and works as follows. A rough vacuum
(about 10-4 torr) is achieved in the reactor. The iodine gas is allowed to flow
into the reactor and over the chromium pieces surrounded by a resistance furnace
that heats the chromium and iodine up to 1100 K. At this temperature the
chromium and iodine react to form CrI2 (gas). The molybdenum ribbon attached to
two nickel electrodes is heated electrically to 1500 K. The CrI2 (gas)
dissociates at the ribbons surface at that temperature and deposits chromium on
the ribbon\'s surface and I gas is returned for further transport of chromium to
the ribbon surface.
In addition to CVD, work has been done on arc melting of samples. This method
will be used to produce the first polycrystalline alloys for testing. Several
samples of intermetallic, Cr2Nb, have been produced. The samples are undergoing
testing and x-ray analysis has already shown that indeed the intermetallic phase
was produced.
Testing
Once samples have been produced, they can be removed for environmental and
mechanical testing. Sample coupons about one inch square will be tested over a
range of high temperatures under various types of atmospheres to measure their
oxidation resistance. Samples will further be evaluated for their tensile
strength and fracture toughness.
New Directions In Chromium Alloys and Single Crystals
The fracture resistance of the Cr2Nb intermetallic and the Cr2Nb-Nb composite
has been reported to be inadequate. Ternary systems involving the addition of a
third element such as Ti to improve the ductility of the Cr-Nb system is yet
another area of investigation. This work would follow up on previous joint
research efforts with LUTCH and fully characterize the effects of alloying
elements on fracture toughness. For CVD of alloys, research must be done on
transport agents to find an acceptable transport agent(s) and temperature regime
capable of depositing both elements simultaneously on the same substrate. Once
the method of producing chromium by CVD has been established, the procedure of
single crystal chromium and chromium alloys can be investigated.
Company Details
Founded in 1985, INSPI research covers a broad range of activities including feasibility analysis for ultracompact nuclear power reactor concepts as well as experimental and theoretical research to establish the fundamental properties of high... more
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