Ex Parte Allen

Board of Patent Appeals and Interferences

Sep 21, 2009

10733738 (B.P.A.I. Sep. 21, 2009)

UNITED STATES PATENT AND TRADEMARK OFFICE
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BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
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Ex parte DAVID B. ALLEN
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Appeal 2009-003117
Application 10/733,738
Technology Center 1700
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Decided: September 21, 2009
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Before EDWARD C. KIMLIN, PETER F. KRATZ, and MARK NAGUMO,
Administrative Patent Judges.

NAGUMO, Administrative Patent Judge.
DECISION ON APPEAL
Appeal 2009-003117
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A. Introduction1
David B. Allen (“Allen”) timely appeals under 35 U.S.C. § 134(a)
from the rejection2 of claims 2, 4-7, 9, 10, and 12-18,3 which are all of the
pending claims. We have jurisdiction under 35 U.S.C. § 6. We AFFIRM.
The subject matter on appeal relates to abrasive tip coatings for
turbine blades. The 738 Specification explains that it is desirable that the
gap between the blade tips and the “ring segments” be made as small as
possible to limit leakage of hot gases past the blade tips. (The ring segments
define, at least in part, the interior of the housing in which the turbines
rotate.) Under normal running conditions, thermal expansion of the
components of the turbine cause the turbine blades to make contact with the
ring segments. According to the 738 Specification, a standard technique for
“controlling” the blade tip clearance is to provide an abradable coating (such
as a “porous thermal barrier coating,” or “TBC”) on the ring segments and to
provide an abrasive material on the turbine blade tips. The abrasive is
selected to be harder than the TBC, which acts as a sacrificial coating that is

1 Application 10/733,738, Turbine Blade Tip with Optimized Abrasive, filed
11 December 2003. The specification is referred to as the
“738 Specification,” and is cited as “Spec.” The real party in interest is
listed as Siemens Power Generation, Inc. (Appeal Brief under
37 C.F.R. § 41.37, filed 31 January 2008 (“Br.”), 3.)
2 Office Action mailed 24 September 2007 (“Rejection”). Although not a
final rejection, the claims have been rejected at least twice.
3 As Appellants note (Br. 5 n. 1), the Examiner’s statements of the
rejections do not reflect the claims as amended on 15 May 2006. The
statements of rejection in this Opinion recite only the presently pending
claims.
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worn away without damaging the turbine blades while it provides an
effective seal for the turbine. A conventional TBC is said to be 8 wt%
yttria-stabilized zirconia ceramic (“8YSZ”). A conventional abrasive
coating is said to be cubic boron nitride (“cBN”).
According to the 738 Specification, a problem with the cBN abrasive
coating is that “thermal decomposition of the cBN particles in an elevated
temperature oxidizing environment produces effectively bare blade tips,
which have been shown to have very limited cutting ability and which result
in unacceptable blade tip wear.” (Spec. 2, ll. 20-24.)
The 738 Specification teaches that this problem is solved by
substituting a portion of the cubic boron nitride with silicon nitride (Si3N4).
(Spec. 3, ll. 6-11.) The 738 Specification explains that, “[w]hile Si3N4 does
not provide the equivalent cutting ability of cBN, due to Si3N4’s lower
hardness, Si3N4 demonstrates greater resistance to thermal degradation in the
high temperature, oxidizing environment of the turbine engine.” (Id. at 5,
ll. 19-22.)
In another embodiment, the 738 Specification teaches that “[t]he
abrasives can be placed, . . . and be included in a super alloy matrix that is
preferably nickel and/or cobalt-based. The super alloy can be CoNiCrAlY
and may have other added elements for enhanced oxidation life.” (Spec. 3,
ll. 13-16.) The 738 Specification explains that “Si3N4 also exhibits excellent
resistance to reaction with cobalt and nickel commonly found in the super
alloy metal matrix used to bond the cBN to the blade tip.” (Id. at ll. 22-24.)
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Representative Claim 2 and 4 are reproduced from the Claims
Appendix to the Principal Brief on Appeal:
2. A turbine blade with abrasive tip coating, comprising:
an elongated turbine blade having a tip at one end,
said tip having an abrasive coating including
a substantially 50:50 mixture of cubic boron
nitride and silicon nitride.
(Claims App., Br. 18; indentation and paragraphing added.)
4. A turbine blade with abrasive tip coating, comprising:
an elongated turbine blade having a tip at one end,
said tip having an abrasive coating including
a mixture of cubic boron nitride, silicon nitride and
CoNiCrAlY.
(Claims App., Br. 18; indentation and paragraphing added.)
The Examiner has maintained the following grounds of rejection:4
A. Claims 2 and 6 stand rejected under
35 U.S.C. § 103(a) in view of the teachings of Schaefer.5
B. Claims 4, 5, 7, 9, 10, and 12-18 stand rejected
under 35 U.S.C. § 103(a) in view of the combined
teachings of Schaefer and Freling.6
C. Claims 4, 5, 7, 9, 12-15, and 18 stand rejected
under 35 U.S.C. § 103(a) in view of the combined
teachings of Schaefer and Ohara.7

4 Examiner’s Answer mailed 29 April 2008. (“Ans.”).
5 Robert P. Schaefer et al., Abrasive Material, Especially for Turbine Blade
Tips, U.S. Patent 4,735,656 (1988).
6 Melvin Freling et al., Columnar Zirconium Oxide Abrasive Coating for a
Gas Turbine Engine Seal System, U.S. Patent 6,190,124 B1 (2001).
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Allen contends that the Examiner erred by reading too much into
Schaefer’s disclosure that various ceramics, including boron nitride, are
known as abrasives, and that the ceramics may be mixed. (Br. 10.) Allen
points out that Schaefer does not “specifically call out the claimed
combination of cubic boron nitride and silicon nitride,” and that Schaefer
does not teach the relative amounts of such materials. (Id.) Moreover, Allen
argues that the claimed invention goes against conventional thinking by
decreasing the amount of the hard cBN in favor of the softer silicon nitride.
(Id. at 11.) Allen also urges that it was surprising that the initial cutting
ability of the 50:50 cBN:SiN mixture was “comparable” to that
of 100 % cBN. (Id., citing Spec. 6, ll. 15-18.) As further evidence of
unexpected results, Allen cites the retention of the benefits of each
component in the 50:50 mixture, namely, the superior cutting properties of
cBN and the greater resistance to thermal degradation of the silicon nitride.
(Id. at 11-12, citing Spec. 5, ll. 26-29.)
Regarding the remaining rejections, Allen argues that the Examiner’s
reliance on Freling and on Ohara fail to cure the deficiencies of Schaefer.
Thus, the remaining arguments are merely cumulative with the arguments
with respect to Schaefer.
The dispositive issues are whether Allen has shown reversible error in
the Examiner’s findings as to the teachings of Schaefer; or whether Allen
has shown unexpected results that rebut a prima facie case of obviousness.

7 Minoru Ohara and Masahiko Mega, Combustion Engine, Gas Turbine,
and Polishing Layer, U.S. Patent 6,896,845 B2 (2005), based on an
application having an effective filing date of 29 April 2003.
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B. Findings of Fact
Findings of fact throughout this Opinion are supported by a
preponderance of the evidence of record.
1. According to the 738 Specification, “approximately equal amounts of
cBN and Si3N4 were applied to subscale turbine blade tips via electroplating
and were tested against a porous 8YSZ coating to measure cutting ability.”
(Spec. 6, ll. 11-13.)
2. The 738 Specification states that the tips were also exposed to
simulated turbine gas path environment for various times to determine their
resistance to thermal degradation. (Spec. 6, ll. 13-15.)
3. In the words of the 738 Specification, “Surprisingly, the initial (non-
thermally degraded) cutting capability of the mixed abrasive tip was shown
to be comparable to a tip with 100% cBN, demonstrating that the blade’s
initial cutting capability is not substantially sacrificed by replacing some of
the cBN abrasive particles with Si3N4.” (Spec. 6, ll. 15-18.)
4. The 738 Specification reports further that
[a]n identical blade was exposed to a 1000°C oxidizing
environment similar to that experienced by an actual turbine
engine blade, for a period of 200 hours. This blade was tested
against a sintered (thermally exposed) porous 8YSZ coating
and its cutting ability, while much reduced versus the fresh
blade, was superior to that of a similarly exposed blade with tip
comprised solely of cBN.
(Spec. 6, ll. 18-23.)
5. The 738 Specification contains no other data or descriptions of these
or similar tests.
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6. Schaefer teaches abrasive ceramic-based coatings for turbine blades.
7. In most relevant part, Schaefer teaches:
Various ceramics may be used, so long as good metal-ceramic
adhesion is achieved. For the abrasive materials which are the
prime object of the present invention, it is necessary that the
ceramic not interact with the metal matrix because this degrades
the wear resistance of the ceramic and thus the entirety of the
material. Ceramics which are not inherently chemically
resistant must be coated as is the silicon carbide. Other
essential materials which may or may not be coated with
another ceramic and which are within contemplation for high
temperature applications include silicon nitrides and the
various alloys of such, particularly silicon-aluminum
oxynitride, often referred to as SiAlON. Boron nitride is a
material that some have favored. Of course, it is feasible to mix
such materials. At lower temperatures, virtually any ceramic
material may be used, depending on the intended use of the
ceramic-metal composite.”
(Schaefer col. 6, l. 54, to col. 7, l. 2 (emphasis added); quoted (without
added emphasis) at Br. 10.)
8. Freling teaches “tip caps” for turbine blades comprising a superalloy
boat comprising an abrasive grit, such as silicon carbide or silicon nitride.
(Freling, col. 1, l. 64, to col. 2, l. 5.)
9. In another embodiment, Freling teaches that electroplated cBN
superalloy blade tips may be prepared. (Freling, col. 2, l. 31-35.)
10. According to Freling, cBN tips “are excellent cutters because cBN is
harder than any other grit material except diamond.” (Freling, col. 2,
ll. 35-37.)
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11. Freling also teaches that “the higher temperatures in the turbine
section can cause the cBN grits and perhaps even the metal matrix to
oxidize.” (Freling, col. 2, ll. 40-43.)
12. Ohara teaches abrasive layers on turbine blade tips. (Ohara, col. 1,
ll. 5-12.)
13. According to Ohara, “since the cubic boron nitride has insufficient
heat resistance, it is turned into boron oxide and sublimated by a long-term
operation in an oxidizing atmosphere, so that the abrasive particle sometimes
disappear.” (Ohara, col. 1, l. 65, to col. 2, l. 1.)
14. Moreover, Ohara teaches that “the abrasive particles sometimes fall
off gradually as MCrAlY is deteriorated at oxidation.” (Ohara, col. 2,
ll. 1-3.)
15. Ohara teaches further that these problems are exacerbated by the
higher temperatures associated with more energy efficient in gas turbines.
(Ohara, col. 2, ll. 7-13.)
C. Discussion
As the Appellant, Allen bears the procedural burden of showing
harmful error in the Examiner’s rejections. See, e.g., In re Kahn, 441 F.3d
977, 985-86 (Fed. Cir. 2006) (“On appeal to the Board, an applicant can
overcome a rejection [under § 103] by showing insufficient evidence of
prima facie obviousness”) (citation and internal quote omitted).
Allen’s criticism that Schaefer does not “call out” the particular
combination of cBN and Si3N4 or the 50:50 ratio, while accurate, does not
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demonstrate that the Examiner erred in concluding that turbine blades
covered by claims 2 and 6 would have been obvious. Allen does not dispute
that Schaefer “calls out” boron nitride and silicon nitride, among other
ceramics. Nor does Allen dispute that Schaefer teaches that combinations of
ceramics may be used. Moreover, Allen does not dispute that Schaefer
provides some guidance as to what properties various combined ceramics
and metals matrices should have, e.g., inertness of the ceramic to the metal
matrix. (Schaefer, col. 6, l. 54-61.) Notably, Allen does not indicate that
those skilled in the art would have thought that cBN and Si3N4 would be
incompatible with any of the conditions cited by Schaefer. Moreover,
Schaefer’s teaching that various ceramics can be combined to form various
abrasive materials indicates that hardness or cutting ability are not the only
considerations for the selection of abrasive ceramics. We also note that both
Freling (col. 1, l. 64, to col. 2, l. 5) and Ohara (col. 1, l. 65, to col. 2, l. 13)
show that the thermal deficiencies of cBN as an abrasive ceramic in turbine
blade tips were known in the art of turbine blade manufacturing. Compared
to the evidence of record, Allen’s argument that reducing the amount of hard
cBN has gone against “conventional thinking” (Br. 11) is unsupported, and
thus entitled to no significant weight.
On the present record, it appears that the combination of elements,
including adjusting the relative amounts, would have been, to paraphrase the
words of the Supreme Court, likely to be obvious if it does no more than
yield predictable results. KSR Int'l Co. v. Teleflex, Inc., 550 U.S. 398, 416
(2007). Allen does not dispute that the combination of ceramics or the
formation of the abrasive coating on the turbine blades would have been
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within the ability of the person of ordinary skill to implement. Accordingly,
we turn to Allen’s arguments for unexpected results.
At first glance, Allen’s argument that a 50:50 cBn:Si3N4 abrasive
mixture having a cutting ability comparable to 100% cBN would have been
unexpected is attractive. However, the 738 Specification does not provide
any more detailed descriptions of the tests and the conditions of the tests
than are provided supra. The reader thus has no basis to evaluate the basis
for the conclusion that the cutting ability was “comparable”; nor does the
reader have any basis to determine whether the characterization
“comparable” is reasonable. The reported superiority of the cutting
characteristics following heat treatment of a turbine blade coated with a
50:50 cBN:Si3N4 mixture is subject to similar criticisms. As our reviewing
court has explained on several occasions, “[i]t is well settled that unexpected
results must be established by factual evidence. Mere argument or
conclusory statements in the specification does not suffice.” In re Soni, 54
F.3d 746, 750 (Fed. Cir. 1995), quoting In re De Blauwe, 736 F.2d 699, 705
(Fed. Cir. 1984).
We conclude that Allen has failed to support its arguments for
unexpected results rebutting the prima facie case of obviousness of turbine
blades covered by claims 2 and 6 with credible factual evidence.
Although Allen provides arguments under separate headings for the
distinct patentability of claims 4 and 18, claim 5, and claims 7, 9, 19, and
12-16 or 12-17 with respect to the rejections over the combined teachings of
Schaefer and either Freling or Ohara, the arguments are substantively
cumulative with the objections to the teachings of Schaefer. Thus, while
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Allen criticizes the alleged failure of a teaching of the combination of cBN,
Si3N4, and CoNiCrAlY super alloy in any of the references (Br. 13-16),
Allen does not explain, for example, why the Examiner erred in holding that
turbine blade tips comprising the combination of the mixed abrasive with the
super alloy would have been obvious. Thus, Allen has done no more than to
attack the teachings of the individual references. However, it is well
established that “[n]on-obviousness cannot be established by attacking
references individually where the rejection is based upon the teachings of a
combination of references.” In re Merck, 800 F.2d 1091, 1097 (Fed. Cir.
1986) (citation omitted.) As for the allegedly unexpected results reported in
the 738 Specification, not only are the showings deficient for lack of data, as
discussed supra, but is there no credible evidence that the coatings were
within the scope of claim 4, i.e., that the abrasive coatings comprised the
CoNiCrAlY super alloy. Moreover, the single cBN:Si3N4 ratio is not
commensurate in scope with the range of cBN:Si3N4 ratios covered by
claim 4 and claims dependent on claim 4.
D. Order
We AFFIRM the rejection of claims 2 and 6 under 35 U.S.C. § 103(a)
in view of the teachings of Schaefer.
We AFFIRM the rejection of claims 4, 5, 7, 9, 10, and 12-18 under
35 U.S.C. § 103(a) in view of the combined teachings of Schaefer and
Freling.
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We AFFIRM the rejection of claims 4, 5, 7, 9, 12-15, and 18 under
35 U.S.C. § 103(a) in view of the combined teachings of Schaefer and
Ohara.
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a).

AFFIRMED

kmm

Siemens Corporation
Intellectual Property Department
170 Wood Avenue South
Iselin, NJ 08830