Appeal No. 1998-2409
Application 08/398,259
stable sulfide or oxysulfide of Ca, Mg, which is stable at a high
temperature. These compounds do not decompose at high service
temperatures to provide free sulfur” (col. 3, lines 48-56). To
accelerate the formation of stable sulfur compounds and thereby
further improve resistance to oxidation, Ca, Mg, rare earths or Y
can be intentionally added to the melt (col. 3, lines 48-66;
col. 6, lines 43-55). Thus, it reasonably appears that
Moroishi’s alloy either has essentially no (i.e., less than about
1 ppm) free sulfur, due to the presence of elements such as Ca
and Mg, or that the reference would have led one of ordinary
skill in the art to add Ca, Mg, rare earths or Y in order to
essentially eliminate any free sulfur and thereby improve
oxidation resistance.
McGill teaches that the substrate onto which his platinum
group metal-containing coating or layer and thermal barrier
coating or layer are applied preferably “comprises an alloy, for
example a Ni-, Co or Fe-based superalloy or a refractory alloy,
or a refractory metal” (col. 2, lines 37-39). McGill’s invention
is described with respect to gas turbine engine components, but
also applies to “other technologies such as coal gasification,
glass processing and oil refining” (col. 4, lines 11-13).
Moroishi’s austenitic steels are used in high temperature
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