TY - JOUR

T1 - Electron microscopy study on the high-temperature oxidation of Si3N4-TiN ceramics

T2 - In situ and ex situ investigations

AU - Feldhoff, Armin

AU - Trichet, Marie France

AU - Mazerolles, Leo

AU - Backhaus-Ricoult, Monika

N1 - Funding Information: A part of this work was supported by the European Commission under contract number HPRN-CT-2000-00044. Composite materials were provided by Professor Martine Desmaison-Brut (University of Limoges, France) and Dr. Alida Bellosi (ISTEC-CNR, Faenza, Italy). The authors are grateful to John Hunt (Cornell Center for Materials Research, Ithaca, NY, USA) for support in ESEM-3 experiments.

PY - 2005

Y1 - 2005

N2 - The high-temperature oxidation of Si3N4-TiN particulate composites with different amounts of the glass forming sinter additives Al2O3 and Y2 O3 has been studied in order to reveal the oxidation mechanism with its different reaction steps and kinetics and especially identify the role of the glass phase in the course of oxidation. The initial stages of oxidation have been observed in situ in an environmental scanning electron microscope while exposing the materials to dry or humid oxidation environment at temperatures between 600 and 1100 °C. For the characterization of the later oxidation stages, materials were oxidized ex situ for longer times. The oxidation scales were characterized by X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy. Oxidation of the compo sites starts at 650 °C, when TiN surface particles begin to oxidize and form on their exposed surface islands of nanocrystalline TiO2. At around 950 °C, the glass transition temperature of the intergranular glass phase, these nanocrystals start to grow laterally on the surface. At the same time, oxidation progresses into the depth of the material, forming thereby several distinguished oxidation subscales. The intergranular glass plays a crucial role for the oxidation in the temperature range between 950 and 1100 °C. Depending on the glass quantity in presence, different reaction mechanisms dominate; the oxidation kinetics are strongly controlled by the transport within the intergranular glass.

AB - The high-temperature oxidation of Si3N4-TiN particulate composites with different amounts of the glass forming sinter additives Al2O3 and Y2 O3 has been studied in order to reveal the oxidation mechanism with its different reaction steps and kinetics and especially identify the role of the glass phase in the course of oxidation. The initial stages of oxidation have been observed in situ in an environmental scanning electron microscope while exposing the materials to dry or humid oxidation environment at temperatures between 600 and 1100 °C. For the characterization of the later oxidation stages, materials were oxidized ex situ for longer times. The oxidation scales were characterized by X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy. Oxidation of the compo sites starts at 650 °C, when TiN surface particles begin to oxidize and form on their exposed surface islands of nanocrystalline TiO2. At around 950 °C, the glass transition temperature of the intergranular glass phase, these nanocrystals start to grow laterally on the surface. At the same time, oxidation progresses into the depth of the material, forming thereby several distinguished oxidation subscales. The intergranular glass plays a crucial role for the oxidation in the temperature range between 950 and 1100 °C. Depending on the glass quantity in presence, different reaction mechanisms dominate; the oxidation kinetics are strongly controlled by the transport within the intergranular glass.

KW - Composites

KW - Corrosion

KW - Electron microscopy

KW - SiN

KW - TiN

UR - http://www.scopus.com/inward/record.url?scp=18144385764&partnerID=8YFLogxK

U2 - 10.1016/j.jeurceramsoc.2004.12.003

DO - 10.1016/j.jeurceramsoc.2004.12.003

M3 - Article

AN - SCOPUS:18144385764

VL - 25

SP - 1733

EP - 1742

JO - Journal of the European Ceramic Society

JF - Journal of the European Ceramic Society

SN - 0955-2219

IS - 10 SPEC. ISS.

ER -