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The influence of grain boundary phase composition on the high temperature properties of Si3N4 materials

 
: Klemm, H.; Herrmann, M.; Schubert, C.

International Conference "Deformation and Fracture in Structural PM-Materials" 1996. Proceedings. Vol. 2
High Tatra, 1996
S.75-84
International Conference "Deformation and Fracture in Structural PM-Materials" <1996, High Tatra/Slovakia>
Englisch
Konferenzbeitrag
Fraunhofer IKTS ()

Abstract
The influence of the grain boundary phase composition on high temperature properties of various silicon nitride materials with Y2O3 as sintering aid was studied. Dependent on the SiO2/Y2O3-ratio grain boundary phase compositions with different crystalline phases were obtained. The materials produced were examined regarding creep, subcritical crack growth (SCG) and their oxidation resistance at temperatures between 1400 and 1500 deg C. Especially the resistance to SCG at elevated temperatures was strongly influenced by the grain boundary composition. An improved SCG-resistance was found for materials with a Y2O3-rich grain boundary phase. This behavior was the consequence of crack healing and crack blunting effects caused by oxidation processes at the surface of the specimen.

: http://publica.fraunhofer.de/dokumente/PX-18413.html