Produção Nacional
Revisado por pares
α-SiAlON–SiC composites obtained by gas-pressure sintering and hot-pressing
2007; Elsevier BV; Volume: 189; Issue: 1-3 Linguagem: Inglês
10.1016/j.jmatprotec.2007.01.015
ISSN1873-4774
AutoresClaudinei dos Santos, Catherine A. Kelly, S. Ribeiro, Kurt Strecker, José Vitor C. Souza, O.M.M. Silva,
Tópico(s)Boron and Carbon Nanomaterials Research
ResumoThe objective of this work was the obtaining "in situ" of α-SiAlON–SiC composite, using an alternative rare-earth oxide mixture, RE2O3, as sintering additive, by two different sintering processes. As sintering additive, 20 vol.% of AlN–RE2O3 in a molar ratio of 90:10 was mixed to the α-Si3N4 powder. In the Si3N4–AlN–RE2O3 powder mixture, 0, 10, 15 and 20 wt.% of SiC were added. The powder batches were milled, dried and compacted by cold isostatic pressing. Two different sintering processes were used: gas-pressure sintering at 1950 °C for 1 h under 1.5 MPa of N2 atmosphere, or uniaxial hot-pressing at 1750 °C, for 30 min under pressure of 20 MPa. The sintered samples were characterized by X-ray diffraction, scanning electron microscopy and mechanical properties. XRD patterns indicate only α-SiAlON (α′) and β-SiC as crystalline phases. It was observed that the SiC addition did not influence the α-SiAlON formation, although the growth of elongated α′-grains is substantially decreased. The hot-pressed composites presented better mechanical properties, exhibiting fracture toughness of 5 MPa m1/2 and hardness around 21.5 GPa.
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