Detrimental effect of s segregation to adherence of Al2O3 coating layer on stainless steels and superalloys.

Oxidation Resistance and Critical Sulfur Content of Single Crystal Superalloys

“…These studies found strong surface segregation of sulfur from very low levels in the bulk, which could then be curtailed by the addition of reactive elements. Subsequent studies confirmed that adhesion could be produced by just reducing the sulfur impurity level, without the need for reactive elements (Smialek, 1987;Smeggil, 1987;Melas and Lees, 1988;Ikeda et al, 1989). Discussion of the exact nature of sulfur segregation and its effects on alumina scale growth continues (Meier et al, 1995;Grabke et al,1995).…”

Beneficial effects of Y2O3 dispersion on Al2O3 protective coating

“…-The chemical composition of alloys used in this work is given in table I. Most of samples were prepared in the same manner as described earlier [6]. Type 304-Y2O3 steel was prepared through ball milling of 304 steel and Y2O3 powders for 3.6 ks (1 h), pressing at 500 MPa (50 kg mm-2), sintering at 1573 K for 3.6 ks and hot-rolling.…”

“…S TRAPPING EFFECT. -High temperature AES (Auger electron spectroscopy) measurements and cyclic oxidation tests on some coating film-alloy systems suggest very strongly that dispersed Y2O3 traps S in the alloy matrix [6]. The first object of this work is to obtain further evidence for the S trapping using other Aln03-alloy systems and to detect S trapped by dispersed oxide with analytical electron microscope.…”

“…Thus we applied this S trapping effect model to an A2O3 coating film-alloy system, where the coating was made under controlled conditions. The S trapping effect of REM was revealed much more clearly for coating film-alloy systems than oxide scale-alloy systems [6]. Because a simulation experiment with a coating film-alloy system is useful in understanding the mechanism of oxide scale spallation, we employed similar systems in this work to elucidate the Y2O3 dispersion effect, in order to examine the following models independently.…”

Stress and Adhesion of Protective Oxide Scales on Stainless Steels and RE Effects

“…The effects of reactive elements (RE) were also reported. [11][12][13][14][30][31][32][33][34][35][36] Smeggil et al 32) showed that adding REs improved scale adhesion due to suppressed segregation of sulfur at the scale-metal interface. However, since they evaluated scale adhesion from mass loss caused by scale spalling during cyclic oxidation, it was difficult to understand the adhesion kinetics of the scale because the scale thickness and other properties were responsible for spalling.…”