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Fabrication and Properties of Si3N4 with Rare Earth Apatite Grain Boundary Phases

  • Terry N. Tiegs (a1), Stephen D. Nunn (a1), Kristin L. Ploetz (a1), Paul A. Menchoffer (a1) and Claudia A. Walls (a1)...

Abstract

The rare earth-oxide and nitride apatites were examined as grain boundary phases in silicon nitride to assess their potential for developing high toughness materials using gas-pressuresintering. Densification was dependent on the quantity of additives used with high densities achieved at equivalent oxygen contents of ∼8%. Fracture toughnesses (KIc) up to 8-10 MPa√m were obtained for some compositions. Ambient temperature flexural strengths were in the range of 400-720 MPa; however, the strengths atelevated temperatures (1200ºC) were reduced from these values.

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Fabrication and Properties of Si3N4 with Rare Earth Apatite Grain Boundary Phases

  • Terry N. Tiegs (a1), Stephen D. Nunn (a1), Kristin L. Ploetz (a1), Paul A. Menchoffer (a1) and Claudia A. Walls (a1)...

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