DETAILED ACTION
Claims 1-22 are pending as submitted on 01/25/24,
claims 18-22 being withdrawn.
Election/Restrictions
Applicant’s election without traverse of Group I, claims 1-17 in the reply filed on April 29, 2026 is acknowledged. Claims 18-22 are withdrawn.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102 of this title, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1-17 are rejected under 35 U.S.C. 103 as being unpatentable over Ito, US 2004/0175549 in view of Nakada et al., US 2015/0079371.
With regard to claims 1 & 8, Ito teaches a known method of bonding two ceramic substrates together (11/17) via applying a joining paste (21) to one or both substrates, wherein said joining paste can comprise particles of rare earth ytterbium compound or the like [0036], and wherein these ceramic substrates can comprise strong/light/low-CTE materials including graphite or mullite therein [0135-0149], and these joined materials are heated to a high temperature, thus forming a strong ceramic joint (throughout, e.g. abstract, [0102-0108 & FIG. 1]).
While this reference does not expressly disclose whether its rare earth joining paste comprises ytterbium disilicate, this was nevertheless a well-known material for bonding strongly to such substrates, as taught for example by Nakada, which teaches that one may apply fluent ytterbium disilicate particles to a ceramic substrate comprising graphite fibers or the like (throughout, e.g. [0037-0039, 0053]). It would have been obvious for one of ordinary skill in the art to combine the teachings & suggestions of Nakada with those of Ito, in order to yield a fluent ytterbium disilicate paste or slurry to bond well to the ceramic substrate material and provide high temperature water resistance in a known manner with predictable success.
With regard to claim 2, a generic step of ‘quenching’ after the heating step in order to lock any desired crystal structures in place is conventional in this art and if not already understood would have been prima facie obvious to incorporate for this benefit.
With regard to claims 3-4, Nakada also teaches the incorporation of mullite [0051-0053] (aluminum silicate) in the ytterbium disilicate layer thus yielding ytterbium aluminum disilicate (Ito also teaches that the substrate/joining paste may be the same material [0150], i.e., the joining paste may also comprise mullite for good bonding).
With regard to claims 5-6, Ito teaches Yb slurries with either aqueous or organic carriers [0104], and Nakada teaches them as a molten spray with little to no carrier [0078] (and otherwise discusses slurries [0069]), wherein determining the concentration of these solutes/solvents would have fallen within the realm of routine experimentation.
With regard to claim 7, Ito generally teaches wide ranges of various exemplary particle sizes to achieve different properties (e.g. [0048, 0087, 0159, 0183]), many of which conform to the claimed range, while Nakada teaches exemplary ytterbium disilicate compound particle sizes of 10 microns [0078], wherein arriving at a claimed size (e.g. 5 microns) in the proposed combination would have been a matter of routine experimentation for one of ordinary skill, depending on the desired properties of the formed layer or its slurry-type coating precursor.
With regard to claims 9-11, Ito teaches the joint may preferably be about 100 microns (~4 mils) [0122], and Nakada teaches preferably about 150 microns (~6 mils) [0055], wherein arriving at a desirable thickness also would have been within the realm of routine experimentation for one of ordinary skill in the art with these known materials.
With regard to claims 12-13, Ito teaches that the ceramic substrate may also comprise SiC [0139], and Nakada teaches the formation of a SiC layer atop the ceramic substrate (abstract, [0042]), wherein this is obvious for one of ordinary skill to incorporate, in order to provide oxidation resistance and a strong bond. Formation of such a silicon-carbon layer either in- or ex-situ would have been obvious to try as these represent the only possibilities (and the substrates of Ito & Nakada may comprise both silicon and/or carbon ‘precursors’ as noted in previous citations).
With regard to claims 14-16, Ito teaches exemplary bonding temperatures of up to 1800 deg. C [0108], wherein the amount of time needed for a complete bonding reaction, relative to material masses, etc, would have fallen within the realm of ordinary skill to achieve the desired bond with predictable success.
With regard to claim 17, as the formed joint is a fused ceramic it is considered to meet the broadest reasonable interpretation of ‘hermetic’ (undefined in this context by Applicants).
Conclusion
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/JOHN BLADES/
Examiner
Art Unit 1746
/PHILIP C TUCKER/Supervisory Patent Examiner, Art Unit 1745
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