Russian materials scientists have developed a material with a record temperature of melting

Material engineers
from nust “MISIS”
synthesized
new material with ultra-high
melting point — nestekhiometriya
the carbonitride of hafnium.
Exactly
measure its melting point
scientists have not yet able, but it is higher than
the carbide
hafnium, most
refractory
of the currently known materials.
Results
research published
in the journal Ceramics
International.

Connection
with ultra-high —
2000 degrees Celsius and above
— melting point is used
in
many areas of modern technology.
Especially
in demand such
materials
in the aerospace industry: for example,
of them made coverings for
nasal
fairings and leading edges of the wings
reusable aerospace
aircraft — when leaving the atmosphere
the temperature of these
details
can reach 4000 degrees Celsius. Below
to find materials with high melting temperature, and suitable mechanical
properties
material engineers are experimenting with
various ceramics: oxides,
nitrides,
carbides
and borides
transitional
metals. In
currently the most refractory
material
call
non-stoichiometric
hafnium carbide HfC0.98

for
it was recorded the temperature
melting 3927 degrees Celsius.

Researchers
from
National
research and technology
University “MISIS” under the leadership of
Dmitry
Moscow (Dmitry
O.
Moskovskikh)
developed
new material with
ultrahigh
melting point
— non-stoichiometric
the carbonitride of hafnium.
Theoretical
calculations
indicated
that such
connections will be
more
more
refractory than pure
carbides,
and
their melting point can be overcome
the threshold of 4000 degrees Celsius. However, the synthesis of
carbonitrides
hafnium
very complex, so
to
and test
them
practice to
recently anyone
failed.

Staff
“MISiS”
suggested
to obtain a non-stoichiometric
carbonitrides
hafnium new
method
which consists of
three
serial
stages.
In
the beginning
the mixed powder of hafnium
with
the coal powder
in
the molar ratio of 2:1 and
grind
in high-speed
drum-ball
mill
within five
minutes.
Grinding
conducted
in an inert atmosphere is
need to excess hafnium is not entered
in the reaction with oxygen.
Activated
in a ball mill
composite
Hf/C
with a particle size of 20-100 microns, then
“burn”
in nitrogen. This
the process is called
self-propagating
high-temperature synthesis,
for
it is necessary high-pressure nitrogen
— 8 atmospheres.
On
this stage, nitrogen is introduced into
the crystal lattice of the composite
turning it into a non-stoichiometric
the carbonitride. The final step is
spark
plasma sintering in nitrogen atmosphere
at a temperature of 2000 degrees Celsius
which forms
from
carbonitride powder
bulk disks with a diameter of 15 millimeters
and a thickness of 2-3 millimeters. At
according to energy dispersive
x-ray
spectroscopy
the ratio of carbon to nitrogen in the resulting
the samples were found to be 1.42.
Thus, the approximate formula
the final connection — HfC0.5N0.35.

Leave a Reply

Your email address will not be published.