TRIBOLOGICAL PROPERTIES AND TESTING OF BEARINGS FABRICATED
FROM HOT-PRESSED SILICON NITRIDE-BASED CERAMICS
I. Yu. Kelina,
I. I. Tkacheva,
A. V. Arakcheev,
N. I. Ershova,
and L. A. Chevykalova
Translated from Novye Ogneupory, No. 10, pp. 50 – 56, October, 2004.
Original article submitted August 28, 2004.
Results of studies of tribological properties of hot-pressed silicon nitride-based ceramics for fabrication
of rolling bearings are reported.
Recently, silicon nitride has gained wide acceptance with
foreign manufacturers as the material for fabricating bear-
ings of various type. This ceramic material is remarkable for
its high hardness and resistance to wear, high resistance to
strain at elevated temperatures, and low density, for example,
in comparison with steel. Another important advantage of
this material is its high and sufficiently stable mechanical
properties which are associated with the finely dispersed
structure, enhanced crystallinity, and infusibility. The high
hardness combined with low abradability allows machining
to a high-surface finish and an extended service life. Further
more, silicon nitride is an electric insulator with high resis
tance to corrosive chemical attack.
The hot-pressed silicon carbide exhibits a strength supe
rior to other ceramic materials, which makes it especially
promising for use in rolling bearings. The hot-pressing tech
nology makes it possible to fabricate rings of diameter up to
250 mm and rolling elements of diameter 4.75 – 25.4 mm.
A ceramic bearing, rolling elements, and bearing cages of
different standard sizes made from hot-pressed materials and
commercially available from the Tekhnologiya RPE are
shown in Fig. 1.
The all-ceramic bearings which are manufactured com
pletely from ceramic are mainly intended for dry, lubri
cant-free run at temperatures up to 1000°C. One is thus also
confronted with the problem of choosing a suitable material
for the bearing cage for operation under these conditions. In
principle, hot-pressed or reaction-bonded silicon nitride can
be used for that purpose; however, until now only nickel-
based alloys were tested.
The hybrid bearings as compared with conventional
bearings can operate at higher speeds and elevated tempera-
tures. Furthermore, they display a higher hardness and are
less susceptible to temperature gradients, and require mini-
mum lubrication. Potentially, one may expect for hybrid
bearings a service life 50 times the service life of steel bear-
ings. Steel bearings can be replaced by ceramic bearings vir-
tually with no change in design.
Properties of steel and silicon nitride-based materials
available from various manufacturers that are used in the
production of bearings [1 – 3] are compared in Table 1. Pho
tomicrographs of ceramic components are shown in Fig. 2.
One will note that physicomechanical properties of OTM-
grade materials, viz., hardness, crack resistance, and
strength, are not inferior to those of ceramic materials avail
able from reputable manufacturers Norton, Saint-Gobain,
Ceradyne, Kyosera, and SKF. As has been reported from
Refractories and Industrial Ceramics Vol. 46, No. 1, 2005
1083-4877/05/4601-0015 © 2005 Springer Science+Business Media, Inc.
Tekhnologiya Research and Production Enterprise (Tekhnologiya
RPE), Obninsk, Kaluga Region, Russia.
Fig. 1. A ceramic ball bearing, rolling elements (a) and bearing
cages of different size fabricated from hot-pressed materials (b ).