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Sintering ZrO2/TiC composites with TiH2. The role of transient liquid phase and of substoichiometry

Sintern von ZrO2/TiC-Keramiken mit TiH2. Die Wirkung einer transienten flüssigen Phase und von Substöchiometrie
: Krell, A.; Blank, P.; Pippel, E.; Woltersdorf, J.


Journal of the American Ceramic Society 78 (1995), Nr.10, S.2641-2647
ISSN: 0002-7820
Fraunhofer IKTS ()
Bruchzähigkeit; composite ceramics; doping additives; Festigkeit; fracture toughness; grain boundary structure; Hartstoffverstärkung; Korngrenzenstruktur; Mischkeramik; oxid ceramics; Oxidkeramik; phase stability; Phasenstabilität; sintering; strength; transient liquid phase; transiente flüssige Phase; zirconia; ZrO2

Sintering tetragonal ZrO2 with 35 vol-% TiC results in a microstructure where all grain facets are free of amorphous interfaces independent of sintering aids as TiH2 or MgO/Y2O3; grain sizes are below 1 mym. With substoichiometric TiC(1-x), a relative density of 95 % and closed porosity are obtained at a lower sintering temperature than with stoichiometric TiC, but subsequent cladless hot isostatic pressing (HIP) is required to achieve 99 % density. High densities of 98 % accompanied by good mechanical properties become possible by pressureless sintering with the use of TiH2. MgO/Y2O3 doping also promotes densification but results in less transformable zirconia and increases the number and size of amorphous triple junctions. The consequences are a lower fracture toughness and strength.