DETAILED ACTION
Application 17/670133, “GLASS CERAMIC SEAL MATERIAL FOR FUEL CELL STACKS”, was filed with the USPTO on 2/11/22 and claims priority from a foreign application filed on 4/5/21.
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
This Office Action on the merits is in response to communication filed on 9/18/25.
Response to Arguments
Applicant’s arguments filed on 9/18/25 have been fully considered, but are not persuasive. Applicant presents the following arguments.
The arguments against the rejections under 35 USC 112 are moot in view of the amendment and/or cancellation of claims 3, 7 and 8.
As to claim 1, incorporating the limitations of cancelled claim 11, there is no reason to combine Badwal and Fleck since Badawal requires a seal material located between interconnects and solid oxide fuel cells of a stack, whereas the Fleck seal is an anti-corrosion barrier. In response, Fleck expressly teaches that the seal is for creating a gas-tight seal and is particularly suitable at high temperatures due to its anti-corrosion properties, and Fleck expressly teaches the seal as useable in a fuel cell. Badwal expresses a need for a “high temperature sealing material”; thus, it is reasonable to take a material which is a high temperature sealing material known in the fuel cell art, even if the specific application of the seal material is somewhat different. The fact that Fleck teaches the sealing material as used on a different portion of a fuel cell stack does not teach away from its use in sealing the fuel cell and interconnector plates, the need in Badwal. Absent such a teaching away, the combination could be considered obvious under a “combining prior art elements” or “applying a known technique to a known device ready for improvement” type rationales (MPEP 2141), with the improvement being Fleck’s express teaching of both desirable sealing and corrosion resistance at high temperatures.
A skilled artsian would have understood that an SOFC is subject to compressive and/or thermal stresses that would not be applied to the corrosion barrier of Fleck; therefore, a skilled artisan would not use the corrosion barrier of Fleck as a solid oxide seal. In response, Fleck’s abstract characterizes the barrier layer as “for gas-tight sealing” at the abstract; therefore, the skilled artisan would understand the material to be a sealing material for SOFC applications. Moreover, the benefit given by Fleck, i.e. desirable sealing and corrosion resistance, are useful in the high temperature SOFC environments, as Badwal express requires a “high temperature sealing material”. This is sufficient rationale for the modification of Badwal in view of Fleck.
Applicant has determined that glass ceramic sealing materials having high barioum oxide content have low viscosity which performs desirably under the deformation present in SOFC high temperature operation. In response, the recognition of another advantage which would flow naturally from following the suggestion of the prior art cannot be the basis for patentability when the differences would otherwise be obvious. See Ex parte Obiaya, 227 USPQ 58, 60 (Bd. Pat. App. & Inter. 1985). Here, the Badwal-Fleck combined embodiment suggests to use the sealing material of Fleck due to its desirable gas sealing and high temperature corrosion resistance properties. The cited art is not required to use the Fleck material for the same advantage as identified by applicant. Since the advantage alleged by applicant is a consequence of the material properties, the same advantage would be achieved, though the prior art need not recognize this advantage.
Applicant’s arguments drawn to claims 21, 28 and 29 are moot in view of the new ground(s) of rejection necessitated by amendment.
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, 12 and 13 is/are rejected under 35 U.S.C. 103 as being obvious over the combination of Badwal (USP 6280868), Lin (USP 9406963) and Fleck (DE 19962782; citations taken from machine translation).
Regarding claim 1, 12 and 13, Badwal teaches a fuel cell stack (Fig. 1; c1:36-49) comprising: interconnects stacked over one another; solid oxide fuel cells disposed between the interconnects (Fig. 1; c1:36-49; c5:14-38); and a seal disposed between the solid oxide fuel cells and the interconnects (“a high-temperature sealing material”, c1:41-46), wherein the interconnect may comprise a chromium iron alloy with chromium and iron contents lying within the 4 to 6 weight percent iron and 94 to 96 weight percent chromium ranges (c4:16-23).
Badwal does not expressly teach that a coefficient of thermal expansion of the interconnects differs from the coefficient of thermal expansion of the solid oxide fuel cells by 1 to 5 percent, or more narrowly 2 to 3 percent.
However, Badwal does further teach that “[t]he preferred interconnect device substrate materials are alloys which have a thermal expansion coefficient closely matching those of the other fuel cell component” with exemplary interconnect thermal connection in the range of 10.5 to 12.0 X 10-6 K (c4:18-21).
Moroever, in the fuel cell art, Lin teaches that mismatch in the thermal expansion coefficients of fuel cell components may cause thermal stress and cracking and that the system is desirably controlled such that the difference in coefficient of thermal expansion between the interconnect and other components of the cell [with the interconnect being the greater of the two] should be between about 0.1 and 0.9 X 10-6 /K, with exemplary magnitudes in the 10.5 to 11.2 X 10-6 /K range (c7:9-60), thereby suggesting percent difference values within or overlapping the 1 to 5%, or more narrow 2 to 3%, claimed ranges (for example, 0.3 / 11 = 2.7%).
It would have been obvious to a person having ordinary skill in the art at the time of invention to configure the fuel cell stack such that the coefficient of thermal expansion of the interconnects is greater than the coefficient of thermal expansion of the solid oxide fuel cells by 1 to 5%, or more narrowly 2 to 3%, for the benefit of reducing thermal stress and likelihood of cracking in the stack as taught by Badwal in view of Lin.
Badwal does not appear to teach wherein the seal is a glass ceramic seal having the claimed chemical constitution.
In the fuel cell art, Fleck teaches a glass ceramic seal (abstract), comprising by weight, on an oxide basis: 30-60% of SiO2; 15-30% of BaO; 10-20% of B2O3; 8-15% of Al2O3 (T016; Fleck claim 2).
These Fleck ranges overlap claimed range of 40-60% of SiO2, 25-28% of BaO, 10-20% of B2O3, and 8-12% of Al2O3 of claim 1. The content of each of of ZrO2, Y2O3, CaO and MgO of claim 1 may be “0”, which is implicitly taught, or at least obvious, in view of Fleck’s omission of these components from the Fleck embodiment (T016, Fleck claim 2).
Therefore, composition of the glass ceramic seal recited in claim 1 is found to be obvious over Fleck which teaches a glass ceramic seal composition having constituent contents substantially overlapping that claimed.
Fleck further teaches that the sealing material is useful at high temperatures used in fuel cells (T014-T015) and that such a seal provides gas-tight sealing and desirable corrosion protection (abstract, T001).
It would have been obvious to a person having ordinary skill in the art at the time of invention to use a glass ceramic composition having composition lying within the range set forth in claim 1 as the seal of the stack, for the benefit of providing gas-tight sealing and desirable corrosion protection, even at high temperatures, as taught by Fleck.
Claims 1, 4-6, 21, 22, 24, 28 and 29 is/are rejected under 35 U.S.C. 103 as being obvious over the combination of Gottman (US 2013/0252119) and Fleck (DE 19962782; citations taken from machine translation).
Regarding claim 1, 28 and 29, Gottman teaches a fuel cell stack (Fig. 1 item 106) comprising: interconnects stacked over one another; solid oxide fuel cells disposed between the interconnects (paragraph [0004, 0024]); and a seal disposed between the solid oxide fuel cells and the interconnects (paragraph [0020]), wherein the seal comprises a glass ceramic seal material (paragraph [0020]).
Gottman further teaches wherein the glass ceramic seals bond the solid oxide fuel cells and the interconnects (the sintering and reflowing of glass-ceramic materials, or precursors thereof, disposed between the fuel cell and the adjacent interconnects, described at paragraph [0020] results in a bond which prevents leakage between components as suggested by “contain and direct fuel and air flows” paragraphs [0024], and paragraphs [0021 and 0079] which suggest that leakage through the seals is considered a failure of the device) d), are disposed directly on the interconnects and the solid oxide fuel cells (paragraphs [0020, 0024]), and are configured to prevent fuel from leaking out of the fuel cell stack (paragraphs [0021, 0079]).
Gottman generally teaches the seal being a glass ceramic seal configured to prevent leakage, but is silent regarding the chemical composition of the glass-ceramic sealing material.
In the fuel cell art, Fleck teaches a glass ceramic seal (abstract), comprising by weight, on an oxide basis: 30-60% of SiO2; 15-30% of BaO; 10-20% of B2O3; 8-15% of Al2O3 (T016; Fleck claim 2).
These Fleck ranges overlap claimed range of 40-60% of SiO2, 25-28% of BaO, 10-20% of B2O3, and 8-12% of Al2O3 of claim 1. The content of each of of ZrO2, Y2O3, CaO and MgO of claim 1 may be “0”, which is implicitly taught, or at least obvious, in view of Fleck’s omission of these components from the Fleck embodiment (T016, Fleck claim 2).
Therefore, composition of the glass ceramic seal recited in claim 1 is found to be obvious over Fleck which teaches a glass ceramic seal composition having constituent contents substantially overlapping that claimed.
Fleck further teaches that the sealing material is useful at high temperatures used in fuel cells (T014-T015) and that such a seal provides gas-tight sealing and desirable corrosion protection at high temperatures (abstract, T001).
It would have been obvious to a person having ordinary skill in the art at the time of invention to use a glass ceramic composition having composition lying within the range set forth in claim 1 as the seal of the stack, for the benefit of providing gas-tight sealing and desirable corrosion protection, even at high temperatures, as taught by Fleck.
Regarding claim 4, Gottman and Fleck remain as applied to claim 1. As to the sealing composition, Fleck further teaches wherein the glass ceramic seal comprises at least one crystalline phase dispersed an amorphous glass matrix phase (“crystals embedded in a glass component”, abstract).
Thus, it would have been obvious to a person having ordinary skill in the art at the time of invention to further incorporate this feature for the same benefit of providing gas-tight sealing and desirable corrosion protection, even at high temperatures, as taught by Fleck.
Regarding claims 5 and 6, Gottman and Fleck remain as applied to claim 1. As to the sealing composition, Fleck further teaches the glass ceramic seal comprising boron oxide and silicon oxide (T016; Fleck claim 2), but is silent as to the crystalline phase comprising cristobalite and barium silicate crystals.
However, a described in MPEP 2112 III, a rejection under 35 USC §103 [and/or 35 USC §102] can be made when the prior art product seems to be identical except that the prior art is silent as to an inherent characteristic.
In this case, the compositional identity of the crystalline phase is a consequence of the precursor components of the glass phase and the heat treatment which nucleates the crystal phase. Applicant’s specification suggests that the sintering of the composition results in the presence of the cristobalite and barium silicate crystal phases (published paragraph [0086]), with the sintering temperature being in the 600 to 1000 °C range (published paragraph [0059]).
Although Fleck is silent as to the compositional identity of the crystal phase, Fleck does teach crystals formed from precursors including silicon and barium oxides as described above. Fleck further teaches sintering the composition at temperatures in the 800 to 1000 °C range (T050, T036) and posits that crystals are nucleated from the glass component precursor in a heat treatment (T050). Therefore, since Fleck teaches the required elemental precursors in the glass phase, and nucleation of crystals therefrom via a similar sintering condition, the same or similar crystal phases [i.e. crystal phases comprising cristobalite [a crystalline silica phase] and barium silicate would result from the temperature high temperature crystal nucleation treatment of Fleck. Neither the Office, nor the prior art, are required to recognize or confirm the identity of the crystal compounds, these found to be inherent crystal constituents which result from the heat treatment of the disclosed glass composition (MPEP 2112 II).
Thus, it would have been obvious to a person having ordinary skill in the art at the time of invention to further incorporate this feature for the same benefit of providing gas-tight sealing and desirable corrosion protection, even at high temperatures, as taught by Fleck.
Regarding claims 21, 22 and 24, Gottman and Fleck remain as applied to claim 1.
Claims 21, 22 and 24 add limitations drawn to the process of forming the glass ceramic. As described in MPEP 2113, “The patentability of a product does not depend on its method of production. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process”.
In this case, as to the named chemical constitution, the cited art teaches glass ceramic compositions which are close enough to that claimed glass ceramics such as to render the compositional requirements obvious as described previously in the rejection of claims 1.
As to the 9/18/25 amendment requiring that the glass ceramic seal material is formed from first and second glass powders that are first mixed and subsequently sintered in the fuel cell stack, firstly, it is noted that applicant’s originally filed specification clarifies that a “mixed powder composition” may actually refer to an ink, rather than a dry powder (applicant’s published paragraph [0088]). Secondly, it is noted that Gottman teaches the seal material may be formed from “glass-ceramic forming powders” which are sintered in-situ in the fuel cell (paragraph [0020]). Lastly, it is noted that Fleck teaches his sealing composition may be a “wet powder” which forms a very even layer upon application (T039) and which melts and flows during the heating step (T032).
It would have been obvious to form the glass ceramic seal by applying a powder and subsequently sintering the powder so that the seal can be effectively formed as taught by Gottman and/or Fleck. Any structure implied by the claimed process is thus expected of the prior art which produces the ceramic seal by a similar method.
Therefore, the claims remain obvious for the reasons previously described, notwithstanding the setting forth of process steps which could be used to make the product.
Claims 2, 3, 9-10, 21, 22 and 24 is/are rejected under 35 U.S.C. 103 as being unpatentable over the combination of Gottman (US 2013/0252119), Fleck (DE 19962782; citations taken from machine translation) and Meinhardt (Meinhardt et al.; Journal of Power Sources; v 182, No. 1, 2008).
Regarding claims 2 and 3, Gottman and Fleck as applied to claim 1. As to the sealing composition, the narrowed content ranges of SiO2, BaO, B2O3, of and Al2O3 still overlap the ranges disclosed by Fleck meaning that the claimed content of each of these constituents remains obvious for overlapping ranges as described in MPEP 2144.05.
Fleck does not appear to teach wherein the glass ceramic composition further includes ZrO2, Y2O3, CaO and MgO in an amount 0.1 to 1% or 0.1 to 0.75% as claimed.
However, each of these constituents were known in the art for use as additives in order to modify or adjust certain properties of the glass ceramic seal composition. For example, see Meinhardt at Table 1 on page 190.
It would have been obvious to a add a small amount, such as within the claimed range, of each additive listed for the benefit of providing and balancing the properties attributed to the constituents in the Meinhardt Table 1 with the other properties implicitly present in the Fleck ceramic glass composition. Moreover, a skilled artisan would have understood that the prominence of each advantage could be increased by adding a certain amount of the constituent, but that an excess amount of each constituent would produce an undesirable effect by substantially changing the properties of the glass ceramic composition from that desired by Fleck. Therefore, the content of each of the additional additives is a result-effective variable subject to routine optimization as described in MPEP 2144.05. Absent a showing of criticality or unexpected results, the composition of claim 2 is found to be obvious over the cited art, notwithstanding the lack of an express teaching of an embodiment within the claimed range because the claimed composition would be expected by the skilled artisan to behave similarly to that disclosed by Fleck without the additional additives, with the provision of some advantage consistent with Meinhardt’s table 1 being expected as a result of adding the additional additives.
As to claim 3, the claim is rejected for the same rationale as is claim 2, i.e. that the claimed value of each constituent lies within the range suggested by Fleck as modified in view of Meinhardt, and no showing of criticality or unexpected results is associated with the claimed composition.
Thus, it would have been obvious to a person having ordinary skill in the art at the time of invention to further incorporate these features in the glass ceramic composition of the fuel cell stack for the benefits taught by Fleck and/or Meinhardt.
Regarding claim 9 and 10, Gottman and Fleck remain as applied to claim 1. As to the sealing composition, Fleck does not expressly teach wherein the viscosity (log h) of the glass ceramic seal is less than 7.5, or more narrowly 5.75 to 7 dPA s at 850 °C.
However, Fleck does teach the glass composition having a viscosity between 105 and 107 Pa s [6 to 8 in log h dPa s] at a temperature range of 800 to 1000 °C, and further teaches that the viscosity properties are important to balance mechanical resiliency and elasticity (T048).
Additionally, it is noted that the Al2O3 is functional to facilitate control of the viscosity (see Meinhardt at Table 1), suggesting that a skilled artisan could tinker with the Al2O3 content within the composition to raise and lower the viscosity in the 6 to 8 range, as desired.
The claimed range is found to be obvious because of the substantial overlap with the range suggested by Fleck, coupled with Fleck’s teaching of viscosity as a result-effective parameter that balances mechanical resiliency with elasticity properties, and optionally with Meinhardt’s teaching that the Al2O3 content can be manipulated to exert additional control over the viscosity. Optimization of known result-effective variables is prima facie obvious.
Regarding claims 21, 22 and 24, Gottman, Fleck and Meinhardt remain as applied to claims 2 and 3.
Claims 21, 22 and 24 add limitations drawn to the process of forming the glass ceramic. As described in MPEP 2113, “The patentability of a product does not depend on its method of production. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process”.
In this case, as to the named chemical constitution, Fleck in view of Meinhardt teaches glass ceramic compositions which are close enough to that claimed glass ceramics such as to render them obvious as described previously in the rejection of claims 2-3.
As to the 9/18/25 amendment requiring that the glass ceramic seal material is formed from first and second glass powders that are first mixed and subsequently sintered in the fuel cell stack, firstly, it is noted that applicant’s originally filed specification clarifies that a “mixed powder composition” may actually refer to an ink, rather than a dry powder (applicant’s published paragraph [0088]). Secondly, it is noted that Gottman teaches the seal material may be formed from “glass-ceramic forming powders” which are sintered in-situ in the fuel cell (paragraph [0020]). Lastly, it is noted that Fleck teaches his sealing composition may be a “wet powder” which forms a very even layer upon application (T039) and which melts and flows during the heating step (T032).
It would have been obvious to form the glass ceramic seal by applying a powder and subsequently sintering the powder so that the seal can be effectively formed as taught by Gottman and/or Fleck. Any structure implied by the claimed process is thus expected of the prior art which produces the ceramic seal by a similar method.
Therefore, the claims remain obvious for the reasons previously described, notwithstanding the setting forth of process steps which could be used to make the product.
Claims 12-13 is/are rejected under 35 U.S.C. 103 as being obvious over the combination of Gottman (US 2013/0252119), Fleck (DE 19962782; citations taken from machine translation), Badwal (USP 6280868) and Lin (USP 9406963).
Regarding claims 12-13, Gottman and Fleck remain as applied to claim 1. Gottman does not expressly teach that a coefficient of thermal expansion of the interconnects differs from the coefficient of thermal expansion of the solid oxide fuel cells by 1 to 5 percent, or more narrowly 2 to 3 percent.
In the fuel cell art, Badwal teaches that “[t]he preferred interconnect device substrate materials are alloys which have a thermal expansion coefficient closely matching those of the other fuel cell component” with exemplary thermal expansion coefficient values in the range of 10.5 to 12.0 X 10-6 K (c4:18-21).
Moroever, in the fuel cell art, Lin teaches that mismatch in the thermal expansion coefficients of fuel cell components may cause thermal stress and cracking and that the system is desirably controlled such that the difference in coefficient of thermal expansion between the interconnect and other components of the cell [with the interconnect being the greater of the two] should be between about 0.1 and 0.9 X 10-6 /K, with exemplary magnitudes in the 10.5 to 11.2 X 10-6 /K range (c7:9-60), thereby suggesting percent difference values within or overlapping the 1 to 5%, or more narrow 2 to 3%, claimed ranges (for example, 0.3 / 11 = 2.7%).
It would have been obvious to a person having ordinary skill in the art at the time of invention to configure the fuel cell stack such that the coefficient of thermal expansion of the interconnects is greater than the coefficient of thermal expansion of the solid oxide fuel cells by 1 to 5%, or more narrowly 2 to 3%, for the benefit of reducing thermal stress and likelihood of cracking in the stack as taught by Badwal and/or Lin.
Badwal does not appear to teach wherein the seal is the glass ceramic seal of claim 1.
In the fuel cell art, as previously described in the rejection of claim 1, Fleck teaches a seal which is a glass ceramic seal and which is the same as, or at least compositionally close enough so as to render obvious, the glass ceramic seal of claim 1. Fleck further teaches that such a seal provides gas-tight sealing and desirable corrosion protection (abstract, T001).
It would have been obvious to a person having ordinary skill in the art at the time of invention to use a glass ceramic composition having composition lying within the range set forth in claim 1 as the seal of the stack, for the benefit of providing gas-tight sealing and desirable corrosion protection as taught by Fleck
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to JEREMIAH R SMITH whose telephone number is (571)270-7005. The examiner can normally be reached Mon-Fri: 9 AM-5 PM (EST).
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/JEREMIAH R SMITH/Primary Examiner, Art Unit 1723