α-SiAlON ceramics with elongated grain morphology using an alternative sintering additive
| Autor: | J. V. C. de Souza, Sebastião Ribeiro, C. Santos, C.R.M. da Silva, Kurt Strecker, Olivério Moreira Macedo Silva |
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| Rok vydání: | 2004 |
| Předmět: |
Sialon
Materials science Mechanical Engineering Metallurgy Oxide Analytical chemistry chemistry.chemical_element Sintering Yttrium Condensed Matter Physics Microstructure Mole fraction chemistry.chemical_compound chemistry Mechanics of Materials visual_art visual_art.visual_art_medium General Materials Science Ceramic Solid solution |
| Zdroj: | Materials Letters. 58:1792-1796 |
| ISSN: | 0167-577X |
| Popis: | In this work, the use of a natural yttrium oxide and rare earth oxide solid solution (CRE 2 O 3 ) as stabilizers of the α-Si 3 N 4 phase to form α-SiAlON has been investigated. This oxide mix is produced at FAENQUIL-DEMAR, at a cost of only 20% of pure commercial Y 2 O 3 . Two α-SiAlONs using pure Y 2 O 3 or CRE 2 O 3 have been prepared, using mixes of 20% by volume of a molar fraction of 9:1 of AlN to Y 2 O 3 or AlN to CRE 2 O 3 , respectively, with 80% α-Si 3 N 4 . Samples were gas pressure-sintered at 1900 °C, under 1.5 MPa of N 2 for 60 min. Both compositions yielded α-SiAlON ceramics with high relative densities (98% t.d.), hardness of 18 GPa and fracture toughness of 5 MPa m 1/2 , with homogeneous microstructures composed of elongated α-SiAlON grains with aspect ratios of 5. It is concluded that the mixed rare earth concentrate (CRE 2 O 3 ) can be used to produce α-SiAlON ceramics with similar microstructures and mechanical properties of α-SiAlON ceramics fabricated using pure Y 2 O 3 , but with the advantage of its lower production cost. |
| Databáze: | OpenAIRE |
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