Fray Symposium - Rare-earth doped Si3N4/SiC micro/nano composites – microstrucure and mechanical properties
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2011-Sustainable Industrial Processing Summit
SIPS2011 Volume 7: Composites, Ceramics, Nanomaterials & Titanium Processing

Editors:Florian K
Publisher:Flogen Star OUTREACH
Publication Year:2012
Pages:646 pages
ISBN:978-0-9879917-6-8
ISSN:2291-1227 (Metals and Materials Processing in a Clean Environment Series)

    Rare-earth doped Si3N4/SiC micro/nano composites – microstrucure and mechanical properties

    Peter Tatarko1; Pavol Sajgalik2; Jan Dusza3;
    1SLOVAK ACADEMY OF SCIENCES, Košice, Slovakia; 2SLOVAK ACADEMY OF SCIENCES, cesta 9, Bratislava; 3SLOVAK ACADEMY OF SCIENCES, Kosice, Slovakia;
    Type of Paper: Regular
    Id Paper: 34
    Topic: 9

    Abstract:

    Influence of different rare-earth oxide sintering additives (La2O3, Nd2O3, Y2O3, Yb2O3 and Lu2O3) on the microstructure and mechanical properties of hot-pressed silicon nitride/silicon carbide micro/nano-composites has been investigated. The results were subsequently compared to those obtained on the Si3N4 monoliths sintered with the same rare-earth oxide additives. The bimodal character of microstructures was observed in all studied materials where elongated β-Si3N4 grains were embedded in the matrix of much finer Si3N4 grains. The fracture toughness values increased with decreasing ionic radius of rare-earth elements in both monolithic and composite systems. Similarly, the hardness and bending strength values increased with decreasing ionic radius of rare-earth elements. The composite materials exibited lower fracture toughness due to their finer microstructure. The positive influence of finer microstructure of the composites on strength was not observed due to the present defects in the form of SiC clusters and non-reacted carbon zones. Wear resistance at room temperature also increased with decreasing ionic radius of rare-earth element in both kind of materials. Mechanical wear (micro-fracture) and tribochemical reaction were found as the main wear mechanisms in all investigated materials. Significantly improved creep and oxidation resistance were observed in the case of composite materials and/or materials with smaller radius of RE3+.

    Keywords:

    ceramics, composites, rare-earth oxides, sintering additives, mechanincal properties, microstructure

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    Cite this article as:

    Tatarko P, Sajgalik P, Dusza J. Rare-earth doped Si3N4/SiC micro/nano composites – microstrucure and mechanical properties. In: Florian K, editors. Sustainable Industrial Processing Summit SIPS2011 Volume 7: Composites, Ceramics, Nanomaterials & Titanium Processing. Volume 7. Montreal(Canada): FLOGEN Star Outreach;2012. p..