Foreign Cooperating Institutions - Institute of Inorganic Chemistry ...
Foreign Cooperating Institutions - Institute of Inorganic Chemistry ...
Foreign Cooperating Institutions - Institute of Inorganic Chemistry ...
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Ceramics nano-composites for the high temperature applications<br />
P. Šajgalík, Š. Lojanová, M. Hnatko, Z. Lenčéš<br />
Silicon nitride based nano-composites<br />
containing silicon carbide nanoinclusions<br />
were prepared by in situ<br />
reactions at the temperature <strong>of</strong> sintering.<br />
Different rare-earth oxides (RE = La,<br />
Nd, Sm, Y, Yb, Lu) were used as<br />
sintering additives. SiC nano-inclusions<br />
were formed by carbothermal reduction<br />
<strong>of</strong> intentionally added fine SiO2. Dense<br />
Si3N4/SiC nano-composites have<br />
exceptional mechanical properties,<br />
especially high temperature creep<br />
resistance. Composite prepared by<br />
addition <strong>of</strong> lutetia has a creep rate<br />
1.6 x 10 –9 s –1 at 1350 °C and 100 MPa<br />
loading.<br />
This value is much lower than the<br />
average values <strong>of</strong> creep rate<br />
commercially available materials and<br />
predetermines this nano-composite for<br />
the high-temperature applications in<br />
extreme conditions. Interestingly also<br />
room temperature properties <strong>of</strong> this<br />
nano-composite were reasonably high.<br />
Lutecia containing nano-composite has<br />
the highest hardness (17.6 ± 0.5 GPa),<br />
quite high fracture toughness (5.0 ± 0.2<br />
MPa⋅m 1/2 ) and strength (652 ± 56 MPa).<br />
All these properties predetermine this<br />
nano-composite for the applications in<br />
extreme conditions, e.g. material for<br />
ceramic glow plug is one <strong>of</strong> the<br />
possibilities.<br />
Further information: P. Šajgalík: pavol.sajgalik@savba.sk<br />
1. Šajgalík P., Hnatko M., Lenčéš Z., Dusza J., Kašiarová M.: Int. J. Appl. Ceram. Technol. 3, 41-46,<br />
2006<br />
2. Šajgalík P, Hnatko M., Lojanová Š., Lenčéš Z., Pálková H., Dusza J.: Int. J. Mater. Res. 97, 772-<br />
777, 2006<br />
3. Dusza J., Kašiarová M., Vysocká A., Špaková J., Šajgalík P.: High Temp. Mater. Process. 26, 7-<br />
16, 2007<br />
13<br />
SiC nano-<br />
inclusions<br />
1µm<br />
Microstructure <strong>of</strong> Si3N4/SiC nano-composites<br />
Deformation/creep <strong>of</strong> prepared lutecia doped ceramic<br />
nano-composite is almost negligible comparing to the<br />
deformation
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