Appeal 2006-2179
Application 10/735,369
formed by applying, on the aluminum-containing or diffusion aluminide
bond coat, a yttria-stabilized zirconia ceramic thermal barrier coating
material (a base layer) and then sintering inhibitor precursor materials (an
overlay layer). See Ackerman ‘633, page 1, paragraphs 0008- 0009 and
page 4, paragraphs 0028-0032, Subramanian, column 4, lines 41-57 and
column 5, lines 43-66. One or more sintering inhibitor precursors can be
applied in a nonsolid (liquid or gaseous) form (which indicates that two or
more inhibitor precursors may be deposited together in liquid form). See,
e.g., Ackerman ‘633, page 5, paragraph 0036. The yttria-stabilized zirconia
taught by Ackerman ‘633 contains about 3 percent to about 12 percent yttria
by weight as required by claim 13 on appeal. See page 4, paragraph 28.
Moreover, Taylor also teaches the importance of having about 6.5 to 9
percent yttria by weight in the yttria-stabilized zirconia thermal barrier
coating of the type employed in Ackerman ‘633 or Surbmanian as required
by claim 13 on appeal to obtain extraordinary good VWR (volume wear
ratio) for the nickel alloy blades for turbine engines. See Taylor, column 5,
lines 24-39, column 6, lines 63-67 and column 7, lines 15-30.
The dispositive question is, therefore, whether it would have been
obvious to apply Group 2 or 3 element and Group 5 element in an atomic
ratio of at least 1:3 on the yttria-stabilized zirconia ceramic thermal barrier
material coated on the gas turbine engine components. On this record, we
answer this question in the affirmative.
As indicated supra, the claimed surface-stabilization composition
comprises at least one Group 2 or 3 element, and at least one Group 5
element of the periodic table, with the Group 5 element being present from
practically near zero (e.g., 100 billion to 3 atomic ratio) to about 75% based
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