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Fluorine-doped reaction bonded MgSiN2

Lences, Z.; Hirao, K.; Hoffmann, M. J.; Kanzaki, S.

Abstract:
Reaction bonded MgSiN2 (RBMSN) with CaF2 and YbF3, as sintering
additives was prepared by direct nitridation Of Si/Mg2Si/Mg/Si3N4
powder compact in a temperature range 1350-1550degreesC. The influence
of the ratio of constituents on the final phase composition, the amount
of sintering additives and the influence of sintering temperature are
discussed. It was shown that the starting powders should be in a ratio
Mg2Si/Mg greater than or equal to 3 and Si3N4/Si-tot greater than or
equal to 0.5 respectively, to obtain single-phase MgSiN2. The oxygen
content of MgSiN2 was in the range of 0.4 - 0.7 wt%. The final density
of pressureless sintered RBMSN with 4 vol% fluoride additives was 85%
of theoretical density. Higher density (similar to92%) was obtained for
the reaction-bonded composite consisting of 48 vol% MgSiN2 and 52 vol%
Si3N4, due to the volume increase after the nitridation of silicon.
The mechanical properties of fluorine-doped RBMSN were further improved
by hot-pressing at 1600degreesC. The 4-point bending strength and
Vickers hardness (HV1) of hot-pressed materials are 427 MPa and 20.8
GPa, respectively. The ... mehr


Zugehörige Institution(en) am KIT Institut für Keramik im Maschinenbau (IKM)
Publikationstyp Buchaufsatz
Jahr 2004
Sprache Englisch
Identifikator ISBN: 0-87849-946-6
ISSN: 0252-1059
KITopen-ID: 1000007642
Erschienen in EURO Ceramics VIII. Hrsg.: H. Mandal. T.2.
Verlag Trans Tech Publ., Uetikon-Zuerich
Seiten 865-868
Serie Key engineering materials ; 264/268,2
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