[Kovove materialy - Metallic materials]
    Fri - March 29, 2024 - 01:47 No. of hits : 1736530 ISSN 1338-4252 (online) ISSN 0023-432X (printed)
© Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Bratislava, Slovak Republic

VOLUME 44 (2006), Issue 2

Influence of sintering additives on indentation cracks and deformation in silicon nitride
GONDAR, E., GABRISOVA, Z., ROSKO, M., ZEMANKOVA, M.
vol. 44 (2006), no. 2, pp. 113 - 118

Abstract
The depth profile of indented cracks in silicon nitride with MgO additive was determined by serial sectioning and observation of fracture areas. These cracks were of Palmqvist’s type, in contrary to the Si3N4 with Al2O3 + Y2O3 additives. A deformed/damaged zone was identified under the indent with a depth ranging from 420 to 490 µm. The volume of the indent represents on average 5 % of the volume of the deformed zone. The deformed zone of silicon nitride with MgO additive was approximately 3 times higher than in the silicon nitride sintered with additives of Al2O3 + Y2O3. The shape of the deformed zone was angular for both materials, although their character is different. In the case of specimens with Al2O3 + Y2O3 additives, the fracture area circumvents the deformed zone, whereas in the case of MgO additive the fracture passes through it. The number of minor cracks, initiated during indentation with Vickers indenter was lower in the case of silicon nitride with MgO additive, which renders the value of fracture toughness more reliable for this material.

Key words
silicon nitride, deformation under indent, depth profile of cracks, serial sectioning, fracture area

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Full title of this journal is bilingual: Kovové materiály - Metallic Materials.
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