30 Effect of a Hydrogen Sulfide-Containing Atmosphere on the Physical. . .
483
Fig. 30.7 The EDX spectra of surface layers of YSZ–Ni cermet specimens after aging in Ar–
5 vol% ° 2 gas atmosphere with an admixture of 7 vol% H 2 S (a) and 18 vol% ° 2 S (b) (see Tables
30.2 and 30.3)
Fig. 30.8 SEM images of the microstructures (a, c) and microfractograms (b, d) of YSZ–Ni
cermet specimens after aging in Ar–5 vol% ° 2 gas atmosphere with an admixture of 7 vol%
H 2 S (a, b) and 18 vol% ° 2 S (c, d)
On the basis of microstructural analysis of the YSZ–Ni cermet specimens
after aging in hydrogenous atmospheres containing 7 and 18 vol% H 2 S, certain
features of changes in their structure and fracture micromechanisms were revealed
(Fig. 30.8). Taking into account the abovementioned peculiarities of the distribution
of sulfur in the volume of treated samples and its insignificant content, even in nearsurface layers of specimens, it can be assumed that the material degrades mainly
due to the action of high-temperature H 2 S gas, which reacts with reduced nickel.