CORROSION-RESISTANT HEATER MATERIAL
FOR A FURNACE USED TO DRAW OPTICAL FIBERS OF QUARTZ GLASS
A. G. Andreev,
M. A. Eron’yan,
I. I. Kryukov,
T. V. Mazunina,
and V. P. Pervadchuk
Translated from Novye Ogneupory, No. 10, pp. 45 – 47, October, 2012.
Original article submitted May 15, 2012.
A study was performed to determine the regimes to be used for nitriding titanium and zirconium, and a theo
retical evaluation was made of the reaction of TiN and ZrN with products from the dissociation of quartz glass
at temperatures of 2000 K. The results show the promise of using nitrides of titanium and zirconium as the ma
terial for the heaters of a furnace which is used to draw optical fibers of quartz glass.
Keywords: nitriding, titanium nitride, zirconium nitride, oxidation of nitrides, heaters, furnace for drawing
Modern units used to draw optical fibers from semifin-
ished products made on the basis of quart glass are equipped
with high-temperature furnaces having heaters made of
graphite  or stabilized zirconium dioxide . Defects that
lower the strength of the fibers are formed on their surface
due to the low heat resistance of ZrO
and corrosion of the
graphite when it reacts with products of the high-temperature
dissociation of the quartz glass.
Nitrides of titanium and zirconium might be able to serve
as alternative materials for the heaters. These nitrides have
particularly high congruent melting points: 3700°C for ZrN
at a nitrogen pressure of 100 at
 and 3280°C for TiN at a
nitrogen pressure of 10 at . These values are considerably
higher than the limit at which ZrO
is thermally stable. Ac
cording to the same sources of information, the melting
points of these nitrides are somewhat lower in nitrogen at at
mospheric pressure: 3250°C for ZrN and 3080°C for TiN.
The partial pressure of the metallic component of each
nitride is especially low, this being true even of nitrogen-de
pleted specimens . Thus, the composition of the nitrides
will be close to stoichiometric in a nitrogen atmosphere at
the temperatures used to draw fibers (2000 – 2200°C). This
completely eliminates the possibility of vaporization of
nitride heaters and keeps solid condensation products from
the gas phase from forming on the surface of the semifin-
ished product. The fact that the oxygen content of the nitro-
gen has been minimized — which is necessary to prevent ox-
idation of the nitrides — prevents the crystallization of semi-
finished products made of quartz glass . Nitrogen does not
react with quartz glass, but it can dissolve in it when the
equilibrium pressure of the oxygen is especially low (less
The use of nitrides of Ti and Zr to make resistance heat
ers is promising from both an economic and a technical point
of view, since metal foil nitrided in nitrogen during its pre
heating can serve as the raw material for the annular heater.
Our goal in this investigation was to determine the tem
perature-time regimes for nitriding titanium and zirconium
foil being heated by an electric current. We also wanted to
study the reaction of TiN and ZrN with products of the disso
ciation of quart glass at temperatures corresponding to the
conditions which exist during the drawing of fibers.
METHODS OF INVESTIGATION
To study the nitriding of titanium and zirconium, we per
formed experiments to determine the nitrogen content of
specimens heated in a hermetic water-cooled chamber in ni
trogen at atmospheric pressure. The chamber had a viewing
hood with a quartz-glass window to measure the temperature
to which the nitrides were heated. The initial specimens, in
the form of tubes made of metal foil with a thickness of
Refractories and Industrial Ceramics Vol. 53, No. 5, January, 2013
1083-4877/13/05305-0335 © 2013 Springer Science+Business Media New York
Perm Scientific-Technical Instrument Manufacturing
Company, Perm, Russia.
Scientific Research and Engineering Institute of Opti
cal Materials Science, St. Petersburg, Russia.
1 at = 0.1 MPa.