Appeal No. 94-4428
Application 08/024,034
achieved by the deposition of a layer of alumina on the nickel
or cobalt aluminide surface, typically by chemical vapor
deposition, followed by heat treatment, typically at a
temperature in the range of about 900-1200EC. As disclosed in
appellant’s specification at page 7, lines 18 through 21, the
heat treatment converts a mostly amorphous aluminum oxide
layer under tensile stress into a spallation-resistant
aluminum oxide layer, which is a stable form of alpha-alumina.
Appellants further indicate that it is believed that the heat
treatment causes tensile cracking of the top alumina layer,
making possible its expansion and contraction without the
production of stresses which result in spallation. Finally, a
thermal barrier coating such as a zirconia coating may be
further deposited on the alumina coated article. See, for
example, dependent claims 2 and 3.
At the outset, we note the examiner’s contention in the
Answer at page 2, which is not disputed by appellant, that the
appealed claims stand or fall together. Thus our focus in
this decision is primarily directed to the rejection of
independent claim 1 for obviousness (35 USC § 103) over
Strangman in view of Lory.
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