Materials Science Forum, Vol.461-464, 857-864, 2004
Oxidation and corrosion properties of the MoAlxSi2-x(C40)/Al2O3 composite
The composite material MoAlxSi2-x (C40)/Al2O3 forms a protective aluminium oxide at low dewpoints and oxygen partial pressures at temperatures up to 1575degreesC. The material is available as a heating element for high temperature laboratory and industrial furnaces under the trade name Kanthal Super ER. The oxidation and corrosion properties of this material were investigated in air, dry nitrogen and hydrogen atmospheres and in a vacuum at temperatures up to 1575degreesC under worst case conditions, i.e. with the protective oxide removed. It was concluded that the material has considerably lower rate of low temperature oxidation than MoSi2 and that the oxidation rate is parabolic at high temperatures in air. In both hydrogen and nitrogen atmospheres at Dp -40degreesC a protective and adherent oxide was formed. Under vacuum conditions the limit for the formation of a protective oxide was 10(-2) mbar at 1575degreesC.