Conferences

High-Temperature (to 1670 C) Air Oxidation of AlN–Si3N4 and AlN–Si3N4–(Ni–Cr–Al) Ceramic Materials

V.Lavrenko,
 
V.Lavrenko,
 
A.Panasyuk,
  

I. M. Frantsevich Institute for Problems of Materials Science of the NAS of Ukraine, Omeliana Pritsaka str.,3, Kyiv, 03142, Ukraine
Powder Metallurgy - Kiev: Frantsevich Institute for Problems of Materials Science NASU, 2010, #03/04
http://www.materials.kiev.ua/article/1559

Abstract

The kinetics and mechanism of high-temperature air oxidation of powders and compact materials with different compositions in the AlN–Si3N4 and AlN–Si3N4–(Ni–Cr–Al) systems are studied using nonisothermal (up to 1500 °С) and isothermal (1350 and 1670 °С) thermogravimetry, DTA, XRD, petrography, and EPMA analysis. During heating, Al4O4–xNx and Si2N2O oxynitrides, α-Al2O3 and α-SiO2 (crystobalite) oxides, and mullite-based Al2O3 · SiO2 solid solution of the boundary composition form during the first oxidation stage, and 3Al2O3 · 2SiO2 mullite forms at higher temperatures (> 1350 °С) in the upper scale layer and aluminum-nickel chromite spinel in the intermediate (barrier) scale layer. The AlN–Si3N4 and AlN–Si3N4–(Ni–Cr–Al) ceramics may be regarded as high-temperature composites (HTCs) owing to their high corrosion resistance.


ALUMINUM AND SILICON NITRIDES, CERAMIC-METAL COMPOSITES, COMPOSITE CERAMICS, HIGH-TEMPERATURE OXIDATION, MULLITE, NICKEL CHROMITE, SELF-REINFORCED SCALE