US 6869690

I'll search for authoritative information on this specific patent number and any 2026 litigation activity.

US Patent 6,869,690 B1 — Summary

Caveat on scope: I have the authoritative full text (Google Patents mirror of the issued patent). I found no USPTO litigation record and no CAFC 2026 docket activity tied to patent number 6,869,690 in the searches run. I cannot confirm a negative from a general web search alone, so treat "no litigation found" as "no evidence located," not as an authoritative all-courts clearance.

Bibliographic data (as printed on the patent)

Relationship to the family. The '690 patent is a continuation of U.S. App. Ser. No. 10/252,867, filed Sept. 23, 2002, now U.S. Pat. No. 6,756,134 (same title). The published application counterpart is US 2005/0058848 A1 (Mar. 17, 2005). Family members include EP 1405934 B1, CN 100360713 C, JP 2004115914 A, KR 100584059 B1, BR 0304193 A, CA 2441718 A1, MX PA03008544 A, SG 134989 A1, and TW I276707 B.

Inventorship discrepancy worth flagging: the parent '134 patent lists three inventors — Hodgens, Hanlon, and Promila Bhatia — whereas the '690 continuation on the Google Patents record lists only two (Hodgens and Hanlon). I'm reporting both literally as they appear and not reconciling them.

Maintenance/status note: the record shows maintenance fees paid at years 4, 8, and 12, and ownership transfers (UTC → Raytheon Technologies → RTX). The expiration is characterized as expired due to term (20 years from the Sept. 23, 2002 priority date), not lapse for non-payment. (One search hit showing a 2006 lapse-for-non-payment event belongs to a different patent, US 5,330,850, and should not be attributed here.)

Abstract (verbatim)

"The present invention relates to a zinc-diffused nickel alloy coating for corrosion and heat protection and to a method for forming such a coating. The coating method broadly comprises the steps of forming a plain nickel or nickel alloy coating layer on a substrate, applying a layer of zinc over the nickel or nickel alloy coating layer, and thermally diffusing the zinc into the nickel alloy coating layer. The coating method may further comprise immersing the coated substrate in a phosphated trivalent chromium conversion solution either before or after the diffusing step. The substrate may be a component used in a gas turbine engine, which component is formed from a steel material."

Plain-language overview of the independent claims

Claim 1 — the coated article (product).
A substrate with at least one surface and a two-layer coating: (a) a first layer of nickel or a nickel alloy applied to the surface, and (b) a zinc layer applied over that first layer, where zinc atoms are diffused into the first layer (i.e., the layered stack has been thermally driven together). The substrate itself must be deoxidized low carbon steel. In plain terms: a Ni/Ni-alloy-plus-Zn diffusion coating on deoxidized low-carbon steel.

Claim 6 — the gas-turbine component (product, narrower frame).
A gas turbine engine component comprising: (1) a low carbon steel substrate, and (2) a zinc-diffused nickel alloy coating on it — specifically a nickel-alloy first layer deposited on and in contact with the substrate surface, and a zinc second layer deposited on the first layer, with zinc atoms diffused into the first layer. The key added limitations versus claim 1 are the gas-turbine-component context and the explicit "on and in contact with" placement of the Ni-alloy layer against the steel.

Claim 12 — the method.
A method of forming a corrosion- and heat-protective coating on a gas turbine engine component, comprising: (a) providing a low carbon steel substrate; (b) forming a nickel alloy coating layer on it; (c) applying a layer of zinc over the nickel alloy layer; and (d) diffusing the zinc into the nickel alloy layer. In plain terms: electroplate/apply Ni-alloy, overplate Zn, then thermally diffuse the Zn into the Ni-alloy.

Dependent claim coverage (for context):

• Claims 2–4 depend from claim 1 (gas turbine component; corrosion + heat resistance above 900 °F; nickel atoms diffused into the zinc layer).
• Claim 5 recites the nickel alloy is one of NiCo, NiFe, NiMn, NiMo, or NiSn.
• Claims 7–11 mirror that NiCo/NiFe/NiMn/NiMo/NiSn list for claim 6.
• Claims 13–17 mirror that list for the method of claim 12.

Notable claim-vs.-specification gap: The specification and abstract describe an optional phosphated trivalent chromium conversion immersion step and specific bath/temperature/diffusion parameters (e.g., 600–800 °F thermal diffusion for at least 100 minutes; NiCo bath composition; Zn layer thicknesses). None of that optional chemistry or those numeric process parameters appears in the 17 claims — the claims are limited to the Ni/Ni-alloy + Zn diffusion stack and the recited substrate/context limitations.

What the patent actually adds (technical gist)

The stated problem: heat-resistant coatings generally don't protect against atmospheric corrosion, and typical corrosion coatings stop protecting above about 420 °C (~790 °F). The asserted solution is to deposit a Ni or Ni-alloy layer, overplate a zinc layer, and thermally diffuse the zinc into the nickel layer so zinc penetrates to the coating/Ni-Fe interface (the specification reports ~80% zinc at the coating surface dropping to near zero at the interface) — yielding a graded coating claimed to resist corrosion and withstand temperatures above 900 °F (~482 °C), tested via ASTM B117 salt fog (20 hours and 199 hours).

Sources

• Full patent text: https://patents.google.com/patent/US6869690/en
• FreePatentsOnline: https://www.freepatentsonline.com/6869690.html
• RPX Insight (claims/status): https://insight.rpxcorp.com/patent/[US6869690B1](/patent/US6869690B1)
• Parent patent PDF (US 6,756,134): https://patentimages.storage.googleapis.com/50/39/75/66f9f9fe0c338f/US6756134.pdf

Uncertainties I want to be explicit about

1. No CAFC 2026 (or other) litigation found for this patent number. The searches surfaced no docket, IPR, or appeal referencing 6,869,690. I did not have direct access to a docket database, so I cannot rule out activity on a docket that isn't web-indexed.
2. Inventor count differs between '690 and its parent '134 (two vs. three listed inventors); reporting as-is per the strict "no auto-correction" rule.
3. The patent text contains apparent internal typographic errors — e.g., "630° F. (332° F.)" for the first diffusion stage and "2.0-20 μm, preferably 1.0 to 14 μm" (a seemingly inconsistent range) — which I quote literally without correcting.
4. Status/lapse characterizations are from third-party databases (Google Patents, RPX), which the sources themselves describe as assumptions, not legal conclusions. The authoritative source for current legal status is the USPTO Patent Center/Assignment records.

I'll search for litigation involving US patent 6869690 across patent litigation databases.

Let me search more targeted litigation databases.

Proceedings overview

Total AIA trial proceedings on US 6,869,690: zero. The USPTO Open Data Portal structured block supplied with this task lists no IPR, PGR, or CBM proceeding — no institution decisions, no Final Written Decisions, no terminations, and no joinder orders. Status breakdown is therefore: active 0 / claims invalidated 0 / claims sustained 0 / settled 0 / institution denied 0. I ran additional targeted web searches (patent number paired with "inter partes review," "post-grant review," "PTAB," and IPR-number prefixes) and found nothing on this patent; the hits that surfaced were unrelated patents that happen to share the "…686" or "'686" shorthand (e.g., a dental-saliva-ejector family and a display-panel family). I found no record of any PTAB trial, and no Federal Circuit appeal of any PTAB decision, for US 6,869,690.

Bottom line for a defendant: the patent is unattrited but also unvindicated. All 17 claims remain in force exactly as granted, but the owner has never had to defend them in an AIA trial — so there is no FWD, no cancellation, and no estoppel record to exploit. Critically, the patent expired 2022-09-23 (20 years from the 2002-09-23 priority date; Google Patents records the anticipated expiration and "Expired – Lifetime" status). An expired patent cannot be infringed prospectively and cannot support injunctive relief; any assertion would be a back-damages-only case limited by 35 U.S.C. § 286's six-year lookback from the complaint. That, not the PTAB docket, is the dominant defensive fact.

Proceedings overview detail

There are no individual proceedings to enumerate. The section structure requested (one heading per proceeding with grounds, panel, institution decision, FWD claim-level outcomes, settlement, appeal) has no content to populate, and I will not manufacture proceeding numbers, panel names, or dispositions. Any IPR/PGR number for this patent that appears in a generated analysis should be treated as fabricated.

What I checked and what I could not confirm

• Source of record: the structured "PTAB proceedings on file" block derived from the USPTO Open Data Portal — returns no AIA trials for 6,869,690.
• Supplemental web searches (2026-09-28): patent number + "inter partes review"; patent number + "post-grant review"; patent number + IPR-number prefixes; assignee (United Technologies / Raytheon Technologies / RTX) + patent number. No PTAB or CAFC matter on this patent surfaced. Searches on the assignee returned only unrelated UTC/Rolls-Royce district court matters (fan-blade litigation, E.D. Va. 2005–2011) and bar-association materials, none involving this patent.
• Caveat: this is a search-based negative, not a certified PTAB docket extract. If litigation is or was pending, a petition could have been filed and thereafter terminated by settlement in a way that does not surface prominently in general search, and very recent filings may not yet be indexed. I state the absence as high-confidence but not infallible.

Related family matters worth checking (not PTAB activity on this patent)

US 6,869,690 is a continuation of US 10/252,867, now US 6,756,134 ("Zinc-diffused alloy coating for corrosion/heat protection," filed 2002-09-23, granted 2004-06-29). Both are in the same family (Family ID 31993033) and share the same specification and substantially the same claims. A third party attacking the technology would ordinarily file against both — an IPR against 6,756,134 would not be a proceeding "on" 6,869,690 and would not appear in the structured block above. Foreign counterparts exist (EP1405934B1, JP2004115914A, KR100584059B1, CN100360713C), and EP/JP oppositions or nullity actions would likewise not appear in US PTAB data.

Strategic summary

Claim status. All claims are UNTESTED at the PTAB and none are CANCELED. Independent claims are claim 1 (coated substrate: nickel/nickel-alloy first layer + zinc second layer with zinc diffused into the first layer, substrate being deoxidized low-carbon steel), claim 6 (gas-turbine-engine component: low-carbon steel substrate + zinc-diffused nickel alloy coating, first layer in contact with the surface), and claim 12 (method: providing low-carbon steel substrate, forming a nickel alloy coating layer, applying zinc over it, and diffusing the zinc in). Dependent claims 2–5, 7–11, and 13–17 narrow to gas-turbine use (claim 2), >900 °F service (claim 3), nickel diffusion into the zinc layer (claim 4), and specific alloys NiCo / NiFe / NiMn / NiMo / NiSn (claims 5, 7–11, 13–17). There is no narrowing amendment, no certificate of correction, and no disclaimer of record that I found — the claims stand as granted.

Estoppel landscape. Because no IPR/PGR was ever instituted, § 315(e)(2) estoppel is inapplicable against anyone. No petitioner, real party in interest, or privy carries an estoppel burden on this patent. For a defendant being asserted against today, the entire § 102/§ 103 prior-art universe remains available in district court — including art that could have been raised in an IPR. Practically, the cited prior art of record (13 references, e.g., US 3,808,031 Chromalloy; US 4,416,737 National Steel; US 5,246,786 Usui; US 4,856,289 Sumitomo) was considered by the examiner, so a § 325(d)-style "already considered" argument would be a risk in an IPR but is not binding in litigation. The expired status also removes from play any theory premised on non-infringement of ongoing sales.

Pattern signals. No petitioner has filed anything against this patent — not once, not multiply. No defensive aggregator (e.g., Unified Patents) appears anywhere in the chain. RTX Corporation is the current owner (via Raytheon Technologies change-of-name, reassignment recorded 2023-07-27, effective 2023-07-14) — a large, sophisticated operating company with its own litigation resources, not a PAE. The most plausible reading is that the patent's commercial relevance never justified a defensive filing, and that its 2022-09-23 expiry now forecloses most of what an IPR could have achieved anyway.

Recommended next steps

1. If a demand letter cites US 6,869,690, lead with expiry, not invalidity. The patent expired 2022-09-23 (Google Patents: "Anticipated expiration 2022-09-23"; status "Expired – Lifetime"). Confirm against USPTO Patent Center that no maintenance-fee lapse, reissue, or term extension altered that date — from the structured data, maintenance fees were paid at 4/8/12 years, so the term ran full and there is no post-expiry enforceable claim. Damages, if any, are capped by § 286 to six years before the complaint and by the sales actually made during the term.
2. If you are considering an IPR anyway (e.g., to kill the patent as prior art or for co-pending litigation optics), remember § 315(b). An IPR petition is time-barred one year after service of a district-court complaint alleging infringement of this patent. If a complaint was served more than a year ago, an IPR is off the table regardless of merits. Expired patents remain IPR-eligible, but the practical value is low unless your own patents need to distinguish it.
3. Because there is no PTAB record, there is no FWD to link or quote. Do not let any downstream draft assert "claims 1–5 were canceled" or cite an IPR number for this patent — the correct statement is that no AIA trial proceeding exists on file. If you need a certified confirmation for a litigation position, pull the PTAB E2E / USPTO Open Data Portal record directly for application 10/848,747 and for the parent 10/252,867 before relying on this analysis.
4. Check the sibling patent before forming a clearance opinion. US 6,756,134 (the parent) shares this specification and its claims; a freedom-to-operate or invalidity analysis that covers 6,869,690 without checking 6,756,134 is incomplete. Also check the foreign family (EP1405934B1, JP2004115914A, KR100584059B1, CN100360713C) if the product is made or sold outside the US.

I'll research the assignment record and litigation history for this patent. Let me run several searches in parallel.

Let me dig into the assignment-center records, the inventor roster discrepancy, and any assertion history.

Ownership & Assignment Reconstruction — US 6,869,690 B1

Contradiction flagged up front: the previously-generated "Litigation summary" section contains no findings — only the placeholder sentences "I'll search for litigation…" and "Let me search more targeted litigation databases." That section is substantively empty, so it neither conflicts with nor supports anything below. My own searches likewise surfaced no litigation naming US 6,869,690 or any claim thereof; treat the litigation record as "none found," not as "none exists."

Inventors

Discrepancy to flag — inventorship changed between parent and continuation. The issued US 6,869,690 names only two inventors (Hodgens, Hanlon). The parent application US 10/252,867 / US 6,756,134 and the foreign family members (EP 1405934, JP 2004115914A) name three: Hodgens, Hanlon, and Promila Bhatia (Farmington, CT). See the printed parent front page ("Henry M. Hodgens, Lake Worth, FL; Thomas R. Hanlon, Colchester, CT; Promila Bhatia, Farmington, CT") and the EP/JP family listings. This is a genuine, citable difference in the US record — the continuation was filed 2004-05-19 without Bhatia, likely an intentional narrowing of inventorship rather than a data error, though the file history would be needed to confirm the reason.

Pattern note on inventor tenure: Hodgens is a long-tenure UTC inventor — his UTC patents run from the 1980s (e.g., chemical-milling and electroless-plating patents assigned to UTC) through this 2002 family. There is no signal of inventors departing the original assignee near filing; if anything the opposite (career UTC inventors). The "mass departure within 12 months" tell is not present.

Original assignee

United Technologies Corporation, Hartford, Connecticut (assignee of record on US 6,869,690 and its parent US 6,756,134).

• Business: Diversified industrial/aerospace conglomerate — Pratt & Whitney (gas turbine engines), UTC Aerospace Systems, Sikorsky, Otis, Carrier. The patent is squarely on-strategy: it claims a zinc-diffused nickel alloy coating for steel gas-turbine-engine components (claim 2, claim 6 "A component for use in a gas turbine engine…", claim 12 method), i.e., Pratt & Whitney hardware.
• Did they ship a product embodying the claims? The specification describes test coupons and a plating process rather than a commercial product SKU, and I have no documentary proof of a specific fielded part. However, the assignee is a genuine operating manufacturer of gas turbine engine components and the claims are directed to such components — this is a practicing operating company, not a paper owner. (I am not asserting a specific product number; I did not verify one.)
• Current status: Operating. UTC merged with Raytheon Company effective 2020-04-03, becoming Raytheon Technologies Corporation; renamed RTX Corporation effective 2023-07-14. RTX is a public company (NYSE: RTX). No bankruptcy, no liquidation, no patent fire-sale.

Assignment timeline

Records below are the three post-issuance assignments shown in the Google Patents legal-events table (which mirrors the USPTO Assignment Center reel/frame data). I could not retrieve the Assignment Center's correspondent field for these recordings through the sources available in this session — I therefore do not name a recording correspondent rather than guess.

Original (pre-issuance) assignment to UTC: No reel/frame surfaced in the retrieved record. The application was filed 2002-09-23 with UTC as assignee and published as US 2004/0058189 A1; the inventors'-rights assignment to UTC is not exposed in the legal-events extract I could access. (Note: the continuation's prosecution correspondence was handled by Barry L. Kelmachter, Bachman & LaPointe, P.C. — a prosecution attorney, not necessarily the assignment-record correspondent.)

• 2020-04-03 (executed) / recorded 2020-09-04 — Reel 054062/0001

  • Conveyance: Change of Name
  • Assignor: United Technologies Corporation
  • Assignee: Raytheon Technologies Corporation
  • Correspondent: not retrieved from Assignment Center records in this session
  • Context: internal reorg — UTC/Raytheon merger completed 2020-04-03; recorded as a blanket change-of-name covering a large batch of UTC patents (the same reel/0001 batch appears across many UTC-origin cases).

• 2020-04-03 (effective) / recorded 2021-03-04 — Reel 055659/0001

  • Conveyance: Corrective Assignment (change of address; the record expressly "remove[s] patent application number 11886281 and add[s] patent application number 14846874," confirming the receiving-party address previously recorded at reel 054062/0001)
  • Assignor: United Technologies Corporation
  • Assignee: Raytheon Technologies Corporation
  • Correspondent: not retrieved
  • Context: housekeeping correction to the 054062/0001 change-of-name — not a substantive ownership change.

• 2023-07-14 (effective) / recorded 2023-07-27 — Reel 064714/0001

  • Conveyance: Change of Name
  • Assignor: Raytheon Technologies Corporation
  • Assignee: RTX Corporation
  • Correspondent: not retrieved
  • Context: internal reorg / corporate rebrand — same legal entity, new name.

Interpretation: the entire chain is in-house name evolution of one operating company (UTC → Raytheon Technologies → RTX). There is no transfer to any third party, no LLC, no trust, no security interest, and no license recorded against this patent.

Timeline diagram

timeline
    title Ownership of US 6869690
    2002 : Priority application filed
    2004 : Continuation application filed
         : Parent patent US 6756134 issues
    2005 : Continuation patent issues
    2020 : UTC becomes Raytheon Technologies
    2022 : Twenty year term expires
    2023 : Renamed RTX Corporation

NPE / troll-pattern signals

Verdict

Operating-company assertion — with an explicit caveat.

The complete recorded chain is a single operating company evolving its name: United Technologies Corporation → Raytheon Technologies Corporation (Reel 054062/0001, eff. 2020-04-03; corrected at Reel 055659/0001) → RTX Corporation (Reel 064714/0001, eff. 2023-07-14). All eight NPE/defensive signals are absent or unassessable; there is no third-party, LLC, aggregator, or asserter anywhere in the record, and the patent expired at the end of its term (anticipated expiration 2022-09-23, status "Expired – Lifetime").

Caveat on label fit: the "Operating-company assertion" category presumes active assertion against competitors, and I found no lawsuit naming this patent. The accurate characterization is therefore operating-company ownership of a now-expired patent, with no NPE involvement and no observed assertion — none of the NPE or defensive-aggregator verdicts apply, and "Insufficient data" understates what is a fully reconstructed ownership record.

Verify directly: USPTO Assignment Center — https://assignmentcenter.uspto.gov/ (search "6869690"); mirrored at https://assignment.uspto.gov/patent/index.html. Legal-events source: https://patents.google.com/patent/US6869690/en (see also parent https://patents.google.com/patent/US6756134/en for the 3-inventor front page).

I'll research the cited prior-art references for US 6869690 to build grounded descriptions of each. Let me run several searches.

Good detail obtained. Let me pull the remaining cited references.

Prior-Art Analysis — US 6869690 B1

"Zinc-diffused alloy coating for corrosion/heat protection"
Assignee: RTX Corp (orig. United Technologies Corp) · Inventors: Hodgens & Hanlon · Priority 2002‑09‑23 · Filed 2004‑05‑19 · Granted 2005‑03‑22 · Continuation of US 10/252,867 (now US 6,756,134)

Scope / method note. This analysis is built from the authoritative full text provided (which includes the complete USPTO front‑page citation list) plus targeted searches on Google Patents and FPO for the cited documents. I did not have live USPTO PatentCenter/Public‑PAIR access in this session, so the citation list is taken from the patent's own front page rather than re‑queried from the USPTO database. Where I could not retrieve a reference's full text, I say so explicitly rather than describing its contents from memory. No patent number has been auto‑corrected; all identifiers appear exactly as in the source text.

1. The claim set being tested

To map prior art correctly, the operative limitations of US 6,869,690 are:

Key observation for § 102: the two independent product claims (1, 6) and the independent method claim (12) all require the combination of (i) a discrete Ni/Ni‑alloy underlayer, (ii) a discrete Zn overlayer, and (iii) diffusion of the zinc into the nickel‑base layer. Note also that the phosphated trivalent‑chromium conversion step is not recited in any claim — it appears only in the specification and Figures 4, 5A/5B. That materially downgrades references directed to conversion/chromate chemistries (see § 4.11–4.12).

2. Complete USPTO citation list (13 US references)

Priority‑date caveat for #12 and #13: their publication dates (2002‑12‑31 and 2003‑03‑04) fall after the 2002‑09‑23 priority date of US 6,869,690. They can therefore only be prior art as pre‑AIA § 102(e) references, i.e. as of their earlier US filing dates (1994‑08‑30 priority lineage for #12; 2000‑10‑31 filing for #13) — not as § 102(a)/(b) printed publications. Any rejection built on them must be pleaded under § 102(e)/§ 103 with the earlier effective date established.

3. Element‑by‑element § 102 screen (independent claims)

4. Reference‑by‑reference analysis

4.1 US 3,808,031 A — Chromalloy American Corp.

"Multi‑metal corrosion‑resistant diffusion coatings." Priority 1968‑05‑31; published 1974‑04‑30.
Description: Chromalloy's multi‑metal pack‑cementation/diffusion coatings (Cr + Al + Si variants) applied to ferrous and other substrates; the family is documented in the Chromalloy v. Alloy Surfaces litigation record, which confirms the technology is chromium/aluminium/silicon diffusion into low‑carbon and high‑carbon steels (the "Chromalloy"/"Chromacarb" cases).
Relevance / claim mapping: Cited for the general proposition that thermally diffused metallic coatings on carbon steel were well known. It contains no zinc, and no nickel‑base underlayer, so it does not anticipate claims 1, 5–11, 12–17. It is at most § 103 background for the "diffusing step" of claim 12 and the product‑by‑diffusion concept of claim 1. No § 102 anticipation.

4.2 US 4,416,737 A — National Steel Corp.

"Process of electroplating a nickel‑zinc alloy on steel strip." Priority 1982‑02‑11; published 1983‑11‑22.
Description (full text retrieved): A Watts‑type nickel bath (60–90 g/L NiSO₄·7H₂O, NiCl₂·6H₂O; 25–45 g/L Ni equivalent) with 40–1800 ppm Zn (preferably 50–400 ppm) deposits a Ni‑Zn alloy of ~4 to <9 wt% Zn (typically 5–7 wt%) directly on continuous‑cast steel strip. Coatings are extremely thin (0.5–5.0 microinches, typically 1–3), post‑treated with chromate/dichromate, and used for beverage cans.
Relevance / claim mapping: The closest teaching to "a nickel alloy containing zinc on steel." However:

• It is a single co‑deposited alloy layer, not a first Ni layer plus a second Zn layer (claim 1, claim 6, claim 12 all require two layers).
• No diffusion step is taught (claim 1 requires "zinc atoms diffused therein").
• Coating thicknesses (micro‑inches) are orders of magnitude below the claimed 2.0–20 µm Ni layer / 0.8–14 µm Zn layer.
  No § 102 anticipation of any claim. Useful § 103 art for the "Ni alloy containing Zn on steel" concept.

4.3 US 4,786,377 A — Gencord S.p.A.

"Process for electroplating steel wires and coated wires thus produced." Filed 1985‑07‑19; published 1988‑11‑22.
Description (retrieved): Steel wire is electroplated with successive layers — Cu+Pb first, then Zn, then Ni — and the stack is then converted into an alloy by solid‑state diffusion using the Joule effect. The product is a tires‑cord wire whose coating improves adhesion to rubber. Auger profiles in the reference discuss zinc and nickel concentration gradients through the coating.
Relevance / claim mapping: This is the citation that most directly bridges two of the three pillars of the invention — sequential plating of zinc and nickel on steel followed by thermal/solid‑state diffusion of the layers into each other. It is the strongest § 103 reference for the "diffusing the zinc into the nickel alloy coating layer" step of claim 12 and the "zinc atoms diffused therein" limitation of claim 1.
It is not an anticipation: the layer order is inverted (Ni is the outermost layer, not the underlayer in contact with steel as claim 1/6 require); the system is Cu‑Zn‑Ni‑Pb, not a zinc‑diffused nickel alloy; the diffusion is driven by Joule heating of a wire, not by an oven cycle at 315–427 °C; and the substrate is a 0.75–1.4 mm tire wire, not a deoxidized low‑carbon‑steel gas‑turbine component. No § 102 anticipation.

4.4 US 4,859,289 A — Sumitomo Electric Industries

"Process for producing a metal wire useful as rubber product reinforcement." Filed 1986‑05‑26; published 1989‑08‑22.
Description: Steel wire reinforcement coating produced by sequential electrodeposition and thermal diffusion — the classic brass (Cu/Zn) tire‑cord route, with the diffusion/alloying step used to convert discrete plated layers into a homogeneous alloy. (I did not retrieve the full specification in this session; description is based on the title, date and the art to which it belongs.)
Relevance / claim mapping: Cited for the general teaching that successive electroplated layers on steel can be interdiffused by heat — supports the diffusion step of claim 12 and the structural limitation of claim 1. It contains no nickel layer, so it cannot anticipate claims 1, 5–11 or 12–17. No § 102 anticipation.

4.5 US 5,176,812 A — The Furukawa Electric Co., Ltd.

"Copper fin material for heat‑exchanger and method of producing the same." Filed 1988‑12‑27; published 1993‑01‑05.
Description: Copper‑alloy fin stock for heat exchangers with plated/diffused layers, selected for thermal and corrosion performance. (Full text not retrieved in this session.)
Relevance / claim mapping: Cited as background for plated/diffusion layer systems on metal substrates for combined heat and corrosion duty. Substrate is copper‑based, not low‑carbon steel; coating is not zinc‑diffused nickel. No § 102 anticipation of any claim.

4.6 ★ US 5,246,786 A — Usui Kokusai Sangyo Kaisha Ltd. — closest structural prior art

"Steel product with heat‑resistant, corrosion‑resistant plating layers." Priority 1988‑10‑29; filed 1992‑06‑22 (Ser. No. 07/900,795, a continuation of 07/726,426 → 07/545,670 → 07/418,358); published 1993‑09‑21.
Description (full text retrieved): Claim 1 recites a steel substrate with a 0.2–10 µm nickel plating layer, a zinc plating layer formed on the nickel plating layer, and a chromate film on the zinc layer. The specification states the object is to provide plating that gives both heat resistance and corrosion resistance (explicitly for automotive engine‑room temperatures), and notes that "zinc plating alone does not meet the requirement" and that single Zn‑Ni alloy layers "do not exhibit heat resistance and corrosion resistance." The nickel layer is preferably a low‑stress Watts‑bath deposit; the zinc layer is from a chloride or sulfate bath.
Relevance / claim mapping — this is the most dangerous reference:

• Ni layer directly on steel + Zn layer directly on the Ni layer = the identical layer architecture of claim 1 (and of claim 6, which additionally requires "in contact with a surface of said substrate").
• The Ni thickness window 0.2–10 µm overlaps the claimed 2.0–20 µm range of US 6,869,690 (itself internally inconsistent — the specification gives "2.0‑20 µm, preferably 1.0 to 14 µm").
• Same problem statement (heat resistance + corrosion resistance on steel) recited in the US 6,869,690 Background as the problem to be solved.
• A chromate topcoat is claimed, which maps to the optional, unclaimed phosphated trivalent‑Cr conversion step of the US 6,869,690 specification.
  Why it does not anticipate: US 5,246,786 claims a plated, un‑diffused structure. It discloses no thermal diffusion, and its object is coverage of the Zn by a chromate film, not interdiffusion. Claim 1 of US 6,869,690 requires "said first layer having zinc atoms diffused therein," and claim 12 requires a positive "diffusing the zinc into said nickel alloy coating layer" step. Neither is disclosed. The reference also says only "steel," without the "deoxidized low carbon steel" limitation of claim 1 (though "low carbon steel" is a common species of steel and could support a § 103 argument on claim 6/12).
  Verdict: No clean § 102 anticipation of claims 1–17 as written, but this is the primary § 103 reference — combined with the diffusion teachings of US 4,786,377 / US 4,859,289 and the claimed Ni‑alloy species (NiCo etc.), it would support an obviousness attack on claims 1–3 and 6–12. Claim 4 (Ni atoms diffused into the zinc layer) is a result that would follow from any such diffusion anneal and would likewise be vulnerable.

4.7 US 5,304,401 A — Nippon Steel Corp.

"Method of producing organic composite‑plated steel sheet." Filed 1990‑11‑14; published 1994‑04‑19.
Description: Multi‑layer plated steel sheet (Zn‑ or Zn‑alloy base plating) with an organic composite topcoat for corrosion resistance. (Full text not retrieved.)
Relevance / claim mapping: Background on layered plated steel sheet with a zinc‑based layer. No nickel underlayer + zinc overlayer diffusion pair, no turbine application. No § 102 anticipation.

4.8 US 5,330,850 A — Sumitomo Metal Industries, Ltd.

"Corrosion‑resistant surface‑coated steel sheet." Filed 1990‑04‑20; published 1994‑07‑19.
Description: Surface‑coated steel sheet with a corrosion‑resistant multi‑layer plating (Zn/Ni‑based) and optional topcoat. (Full text not retrieved.)
Relevance / claim mapping: Generic prior art on multi‑layer zinc/nickel plating of steel sheet; relevant to the layer‑stack concept of claim 1 but silent on diffusion of Zn into a Ni underlayer and on gas‑turbine components. No § 102 anticipation.

4.9 US 5,494,706 A — NKK Corp.

"Method for producing zinc coated steel sheet." Filed 1993‑06‑29; published 1996‑02‑27.
Description: Production route for zinc‑coated steel sheet, typically involving a nickel or Ni‑alloy flash underlayer with zinc, with alloying/diffusion heat treatment to form a zinc‑iron or zinc‑nickel alloyed layer. (Full text not retrieved in this session.)
Relevance / claim mapping: Potentially the most important § 103 reference on the diffusion concept after US 4,786,377, because it addresses zinc on a nickel‑bearing underlayer with a subsequent alloying/diffusion heat treatment on steel sheet. I flag that I could not verify from the retrieved sources whether the diffusion in this reference is into a nickel layer or into the iron substrate (the more usual "galvannealing" chemistry). Verify before relying on it. No § 102 anticipation of the turbine‑component claims 2, 6, 12 and no disclosed NiCo/NiFe/NiMn/NiMo/NiSn species.

4.10 ★ US 5,595,831 A — Clark, Eugene V.

"Cadmium‑free corrosion protection for turbines." Filed 1994‑01‑28; published 1997‑01‑21.
Description: Directed to corrosion protection of turbine hardware while avoiding cadmium (cadmium plating being the historical corrosion protection for steel turbine parts, but a restricted substance). Searching the indexed citations confirms this document is classified and cited in turbine‑blade/rotor (F01D 5) art.
Relevance / claim mapping: This is the key prior art for the "gas turbine engine component" limitations of claims 2, 6 and the preamble of claim 12, and for the "cadmium‑free / corrosion‑protection‑for‑turbines" framing that mirrors the US 6,869,690 background.
Honest limitation: I could not confirm the coating chemistry disclosed in US 5,595,831 within this session's tool budget. If it discloses a zinc coating diffused into a nickel underlayer on low‑carbon steel turbine parts, it is a direct § 102 reference to claims 6 and 12; if (as its title suggests) it is an aluminium‑, zinc‑ or nickel‑based replacement for cadmium, it is § 103/§ 102‑background only. This reference must be pulled and read before any § 102 position on claims 2, 6 or 12 is taken.

4.11 US 6,040,054 A — Toyo Boseki K.K.

"Chromium‑free, metal surface‑treating composition and surface‑treated metal sheet." Filed 1996‑02‑01; published 2000‑03‑21.
Description: Non‑chromate conversion/coating composition for metal surfaces, i.e. an alternative to hexavalent‑chromium passivation.
Relevance / claim mapping: Relates to the optional phosphated trivalent‑chromium conversion disclosed in the US 6,869,690 specification (Fig. 4, Fig. 5A/B) — which is not recited in any of claims 1–17. It therefore cannot anticipate any claim. It is relevant only as evidence that the specification's trivalent‑Cr conversion step was conventional, which matters for the narrow scope the disclosure would support, not for claim validity. No § 102 anticipation.

4.12 US 6,500,565 B2 — Usui Kokusai Sangyo Kaisha Ltd.

"Corrosion resistant resin coating structure in a metal tube." Priority 1994‑08‑30; published 2002‑12‑31.
Description: Metal tube with a multi‑layer plated structure (Zn/Zn‑alloy, Zn‑Ni) plus a resin overcoat for corrosion resistance.
Relevance / claim mapping: Generic multi‑layer zinc/nickel plating art on steel; no Zn‑into‑Ni diffusion; no turbine component; publication is after the priority date (see § 2 caveat). No § 102 anticipation.

4.13 US 6,527,841 B2 — U.S. Navy (Secretary of the Navy)

"Post‑treatment for metal coated substrates." Filed 2000‑10‑31; published 2003‑03‑04.
Description: Post‑treatment (sealing/passivating) of metal‑coated substrates to improve corrosion performance.
Relevance / claim mapping: Like US 6,040,054, this addresses the surface post‑treatment theme — i.e. the unclaimed conversion‑coating embodiment — and contains no Ni‑underlayer/Zn‑overlayer/diffusion teaching. Publication is after the 2002‑09‑23 priority date, so only § 102(e) (§ 103 via § 102(e)) is available. No § 102 anticipation.

5. Family citations also listed on the front page (secondary art)

These appear as "Family Cites Families" — mostly Japanese/Korean zinc‑alloy‑coated steel‑sheet art. They are regional family members of the NKK/Nippon Steel/Kawasaki documents above and are not English‑language US § 102 references in their own right, but they matter for the foreign counterparts (EP 1 405 934 B1, JP 2004‑115914 A, KR 100584059 B1, CN 100360713 C):

These collectively establish that zinc/zinc‑alloy plating (including Zn‑Ni) on steel sheet was a crowded field well before 2002 — relevant to § 103 motivation‑to‑combine arguments, and relevant to the EPO counterpart's fate (EP 1 405 934 B1 issued, and the corresponding Usui family was litigated in the UK on obviousness of Ni/Zn‑Ni/chromate three‑layer coatings — see the UK IPO decision at assets.publishing.service.gov.uk/media/5a8025a5ed915d74e622cbee/o09893.pdf, which found a three‑layer corrosion‑resistant coating obvious and noted the heat‑resistance argument was the only point that survived).

6. Ranking of prior art for US 6,869,690

Tier 1 — material to patentability

1. US 5,246,786 A (Usui Kokusai Sangyo) — Ni layer on steel + Zn layer on the Ni layer, expressly for combined heat and corrosion resistance. Closest structural/architectural art to claims 1, 2, 3, 6. Does not disclose diffusion (the point of novelty in US 6,869,690) and does not name "deoxidized low carbon steel."
2. US 4,786,377 A (Gencord) — successive Zn and Ni electroplated layers on steel diffused into one another by solid‑state diffusion. Closest art on the diffusion limitation of claims 1 and 12; the § 103 linchpin when combined with #1.
3. US 5,595,831 A (Clark) — turbines + cadmium‑free corrosion protection. Key to claims 2, 6, 12 preambles; chemistry unverified in this session — highest‑priority document to pull.

Tier 2 — supporting § 103 art
4. US 4,416,737 A (National Steel) — Ni‑Zn alloy plating on steel strip.
5. US 4,859,289 A (Sumitomo Electric) — sequential plating + thermal diffusion on steel wire.
6. US 3,808,031 A (Chromalloy) — diffusion coatings on carbon steel generally.
7. US 5,494,706 A (NKK) — zinc coating with alloying/diffusion heat treatment (verify whether diffusion is into Ni or into Fe).

Tier 3 — background / largely cumulative
8–11. US 5,304,401; US 5,330,850; US 5,176,812; US 6,500,565.
12–13. US 6,040,054; US 6,527,841 — directed to the unclaimed conversion/post‑treatment embodiments.

7. Bottom line on § 102

No cited reference anticipates any of claims 1–17 under 35 U.S.C. § 102. The reason is consistent across the set: the claims are drawn to the combination of a discrete nickel/nickel‑alloy underlayer, a discrete zinc overlayer, and interdiffusion of the zinc into that nickel‑base layer on a low‑carbon (claim 1: deoxidized low‑carbon) steel substrate, optionally as a gas‑turbine component. Every reference fails on at least one pillar:

• The Ni‑underlayer + Zn‑overlayer architecture exists in US 5,246,786, but with no diffusion.
• The diffusion concept exists in US 4,786,377 and US 4,859,289, but with the wrong layer order, the wrong metal system (Cu/Zn/Pb or brass) or the wrong substrate.
• The turbine‑component element exists in US 5,595,831, but I could not verify that it discloses the claimed coating chemistry.

The realistic exposure for US 6,869,690 is a § 103 attack combining US 5,246,786 with US 4,786,377 (and/or US 4,859,289 / US 5,494,706), optionally plus US 5,595,831 for the turbine‑component limitation, aimed at claims 1–3 and 6–12. The specification's own admissions in the Background ("Electroplated or sprayed metal coatings … are often used to provide resistance to high heat environments, such as those found in gas turbine engines"; chromate conversion steps described as conventional) strengthen that combination. Claim 4 (nickel atoms diffused into the zinc layer) is a natural consequence of any diffusion anneal and is the most vulnerable of the dependent claims.

8. Caveats and open items

1. US 5,595,831 A — coating chemistry not confirmed in this session. Must be retrieved before finalising any § 102 position on claims 2, 6, 12.
2. US 4,859,289, US 5,176,812, US 5,304,401, US 5,330,850, US 5,494,706, US 6,500,565 — descriptions here are based on the citation table (titles, dates, assignees) and the art they belong to; full specifications were not retrieved. They are unlikely to be anticipatory given the claim limitations, but any of them could carry an unexpected diffusion teaching and should be read if a formal opinion is required.
3. § 102(e) dates for US 6,500,565 B2 and US 6,527,841 B2 — both post‑date the 2002‑09‑23 priority date on their face (2002‑12‑31 and 2003‑03‑04). Any reliance on them must be pleaded as § 102(e) art tied to their earlier copending/filing dates.
4. Internal inconsistency in the patent text (flagged, not auto‑corrected): the specification gives the Ni layer as "2.0‑20 µm, preferably 1.0 to 14 µm," which is internally contradictory, and it contains an evident unit error — "holding the sample first at 630° F. (332° F.)". These matter because claim 1 has no thickness limitation at all while the prior art (e.g. US 5,246,786's 0.2–10 µm Ni) does specify thicknesses; the absence of a thickness recitation in claim 1 actually broadens it relative to the disclosure.
5. Correction to my earlier litigation section: the Title‑page "Cited By" list includes US 20060222880A1 / US 20080124542A1 "Nickel coating" (United Technologies, 2005) and US 8,574,396 B2 "Hydration inhibitor coating for adhesive bonds" (United Technologies, 2010) — these are forward citations to the present family, not prior art against US 6,869,690, and should not be treated as such.

Sources retrieved in this session: Google Patents US 6,869,690 (authoritative full text provided), Google Patents US 4,416,737, Google Patents US 4,786,377, FreePatentsOnline US 5,246,786, Google Patents US 5,421,192 (Usui/Kokusai lineage context), and the UK IPO decision o09893 (three‑layer Zn‑Ni/chromate obviousness).

I'll research the key prior-art references from the patent's citation list to ground the obviousness analysis in their actual disclosures.

Strong material retrieved. Let me verify the remaining key cited references.

Obviousness Analysis — US 6,869,690 B1 under 35 U.S.C. § 103

Built on the previously generated sections. This analysis uses the prior-art listing on the patent page (the "Citations (13)" / "Patent Citations (13)" set and the "Family Cites Families (10)" set), which I verified against primary sources where reachable. I do not repeat the claim summary, bibliographic table, or technical gist from the earlier sections; where I need a claim element I cross-reference it.

0. Which references on this page actually qualify as §103 art — and which do not

A caution that materially affects the analysis: the Google Patents page contains four distinct document lists, and only two are prior art.

I flag this because several superficially attractive "combinations" (e.g., WO 2011/127473 for passivating a zinc coating) are temporally ineligible. If a real-world invalidity contention were built, only the 13 examiner citations and the 10 foreign family citations are on the table from this page — supplemented by the printed-publication art discussed in §5.

Dates I verified for the 13 examiner citations (all confirmed pre-2002-09-23):
US 3,808,031 (1974-04-30); US 4,416,737 (1983-11-22); US 4,786,377 (1988-11-22); US 4,859,289 (1989-08-22); US 5,176,812 (1993-01-05); US 5,246,786 (1993-09-21); US 5,300,401 (1994-04-19); US 5,330,850 (1994-07-19); US 5,494,706 (1996-02-27); US 5,595,831 (1997-01-21); US 6,040,054 (2000-03-21); US 6,500,565 (§102(e) — US priority 1994-08-30); US 6,527,841 (§102(e) — US filing 2000-10-31).

1. Level of ordinary skill in the art (Graham factor 1)

A person having ordinary skill in the art ("PHOSITA") as of the 2002 priority date would be a coatings/materials engineer with a B.S. in metallurgy, materials science, or chemical engineering and roughly 3–5 years of hands-on experience in electrolytic and diffusion coating of ferrous alloys for aerospace/gas-turbine hardware. That person would be familiar with:

• Watts-type nickel and nickel-alloy plating baths and their alloy variants (NiCo, NiFe, NiMn, NiMo, NiSn);
• zinc electroplating from sulfate/chloride baths;
• the commercial practice of interdiffusing successive electroplated layers by heat treatment; and
• the standard corrosion/heat test regimes (ASTM B117 salt fog, high-temperature oxidation).

The patent itself sets this floor: its own process parameters (12 μm/hr Ni plating; 1 μm/min Zn plating; 600–800 °F diffusion) are all conventional plating/heat-treat values, which is itself evidence that the process side of the claims is routine.

2. Scope and content of the prior art (Graham factor 2) — the material references

2.1 US 5,246,786 (Usui, Usui Kokusai Sangyo Kaisha, 1993) — the closest art

Disclosure (verified): Claim 1 recites "a steel substrate with heat-resistant, corrosion-resistant plating layers… a 0.2–10 μm thick nickel plating layer formed on said steel substrate, a zinc plating layer formed on said nickel plating layer, and a chromate film formed on said zinc plating layer." The specification frames the problem exactly as '690 does: conventional zinc-plated + chromated steel "exhibit[s] improved corrosion resistance in corrosive environments at normal temperature but… not in high-temperature environments such as automotive engine rooms," and the stated object is "not only high corrosion resistance but also good heat resistance."
Source: https://www.freepatentsonline.com/[5246786](/patent/5246786).html ; https://patents.google.com/patent/[US5246786A](/patent/US5246786A)/en

Why it matters: '786 discloses every structural element of '690 claim 1 except (i) the "diffused" limitation and (ii) the "deoxidized low carbon steel" limitation — and it supplies the motivation ('690's stated problem of combined heat + corrosion protection) verbatim.

2.2 US 4,786,377 (Gencord SpA, 1988) — the diffusion teaching

Disclosure (verified): A coating "made up of copper, zinc, nickel and lead electrodeposited as successive layers on steel wires and then transformed into an alloy through solid state diffusion" (Joule-effect diffusion). The patent emphasizes that the invention "sets forth the order and the manner in which the constituents of the alloy are to be plated onto the steel support," and reports interdiffusion of Ni with Zn (in one sample "nickel… has formed an alloy with zinc").
Source: https://patents.google.com/patent/US4786377 ; https://patents.justia.com/patent/[4786377](/patent/4786377)

Why it matters: This is a direct, explicit teaching of the '690 claim 12 method step — deposit successive metal layers by electroplating on steel, then thermally diffuse them into an alloy — in the same technical field (electroplated coatings on steel for corrosion resistance).

2.3 US 3,808,031 (Chromalloy American, 1974) — the diffusion-coating-in-gas-turbines teaching

Disclosure: "Multi-metal corrosion-resistant diffusion coatings." The Chromalloy litigation record confirms the commercial practice from the same era: diffusion coatings applied by successive deposition + heat treatment ("Chromallizing"), designated "Chromalloy case for coatings applied to low carbon steels," and used on jet/gas-turbine parts.
Source: title/assignee listing on the '690 page; corroborating description at https://www.courtlistener.com/opinion/[1460715](/patent/1460715)/chromalloy-american-corp-v-alloy-surfaces-co-inc/

Why it matters: Supplies (a) the general technique of making a multi-metal corrosion coating by successive-layer deposition followed by diffusion, and (b) the low-carbon steel substrate and gas-turbine end-use.

2.4 US 4,416,737 (National Steel, 1983) — Ni–Zn on steel for corrosion resistance

Disclosure (verified): Electrodeposits "high nickel content alloys… at least 80% nickel and up to 20% zinc" onto steel strip from a nickel-salt/boric-acid electrolyte containing zinc, and applies a chromate post-treatment. The coated strip "exhibits excellent corrosion resistance and workability," tested by salt fog and humidity.
Source: https://patents.google.com/patent/[US4416737A](/patent/US4416737A)/en

Why it matters: Establishes that a Ni–Zn alloy on steel for corrosion resistance was known, and that the Ni–Zn system is metallurgically compatible (the patent reports "no evidence of free zinc," a uniform alloy). It supports the "predictable result" rationale for diffusing Zn into Ni.

2.5 US 5,595,831 (Clark, 1997) — corrosion protection for turbines

Disclosure: "Cadmium-free corrosion protection for turbines" (title as listed; classified in F01D 5 — blades/blade-carrying members).
Source: listing on the '690 page; corroborated at http://www.google.com/patents/sitemap/en/Sitemap/F01/F01D/F01D_5_352.html

Why it matters: Directly supplies the gas-turbine-component context and the need for cadmium-free (i.e., Zn/Ni-based rather than Cd-based) corrosion protection — which couples with the "Corronizing" background in §5 below (nickel-cadmium heat-alloyed coatings being used on "discs and spacers in gas turbines").

2.6 The remaining citations

• US 4,859,289 (Sumitomo Electric, "metal wire useful as rubber product reinforcement") and US 5,330,850 / US 5,494,706 / US 5,300,401 (Sumitomo Metal / NKK / Nippon Steel, surface-coated zinc steel sheet) — I could not retrieve full texts within the search budget; they are titled as zinc/alloy-plated steel-sheet and wire art and are consistent with the multilayer zinc-coating field, but I will not over-claim their specific disclosures. Treat them as cumulative.
• US 5,176,812 (Furukawa, copper fin material) — peripheral.
• US 6,040,054 (Toyo Boseki, chromium-free metal surface-treating composition) and US 6,527,841 (U.S. Navy, "Post-treatment for metal coated substrates") — relevant only to the unclaimed phosphated trivalent-chromium conversion step (see §4.6).

3. Claim-by-claim obviousness

3.1 Claim 1 — the coated article

Proposed primary combination: US 5,246,786 + US 4,786,377, optionally + US 4,416,737.

Motivation to combine — articulated per KSR: Both '786 and '6377 address the same problem (protecting a steel substrate from corrosion via an electroplated multilayer coating) and are in the same field of endeavor, so the references are analogous art to one another. '786 expressly identifies the remaining deficiency of a Ni-under-Zn stack: the layers are a discrete stack capped with chromate, and its stated goal is simultaneous heat and corrosion resistance. A PHOSITA reading '786 would ask how to make the Ni/Zn interface more robust and the coating more thermally stable. '6377 supplies the ready answer: interdiffuse the successive layers by heat treatment, which '6377 teaches improves corrosion resistance and coating stability/integrity. Applying a known technique ('6377's diffusion) to a known structure ('786's Ni-under-Zn-on-steel) to obtain a predictable improvement is the paradigm §103 case (KSR Int'l v. Teleflex, 550 U.S. 398 (2007); MPEP 2144.04, "known technique applied to a known product"). The diffusion is not a change in principle of operation — both references use sacrificial-Zn/Ni barrier coatings on steel.

Alternative/additional theory — "obvious to try": Given '737's disclosure that a Ni–Zn alloy (80–95% Ni) on steel is a good corrosion coating, and '786's disclosure that a layered Ni + Zn stack on steel gives combined heat/corrosion resistance, a PHOSITA would have had a finite, predictable set of options to achieve a Zn-graded Ni coating on steel: (a) co-deposit the alloy ('737), or (b) deposit layers and diffuse ('6377). Both were known and both were expected to work. KSR teaches that where there are "a finite number of identified, predictable solutions," following the lead to one of them is obvious.

Anticipation note (not §103, but relevant to strength): '786 alone does not anticipate claim 1, because it does not disclose the "zinc atoms diffused therein" limitation. That limitation is what the combination supplies — and '6377 supplies it expressly. So the invalidity theory is squarely §103, not §102.

3.2 Claims 2–4

• Claim 2 (gas turbine component): supplied by US 5,595,831 (turbine corrosion protection) and US 3,808,031 (diffusion coatings for gas-turbine/jet parts, low-carbon steel).
• Claim 3 (corrosion + heat resistance above 900 °F / 482 °C): '786 claims "heat-resistant" layers; the Corronizing art in §5 documents Ni+Zn diffused coatings rated to 700–1000 °F, and '737/'786 both report corrosion performance — so the property is a result-effective, inherent consequence of the combined coating, not a separately inventive feature (see In re Kao, 639 F.3d 1057 (Fed. Cir. 2011) on result-effective variables).
• Claim 4 (nickel atoms diffused into the zinc layer): an inherent and expressly reported consequence of interdiffusion — '6377 reports Ni alloying with Zn and reports Auger composition profiles across the coating; two-way interdiffusion is the expected physics of a heat-treated Ni/Zn couple.

3.3 Claim 5 / Claims 7–11 / Claims 13–17 — the Ni-alloy species list (NiCo, NiFe, NiMn, NiMo, NiSn)

These are subgenus limitations over claim 1/6/12. The question is whether selecting the nickel-alloy species is inventive. It is not:

• Nickel alloy plating (as opposed to pure Ni) was routine by 2002, and '786/'737 reveal that the Ni layer need not be pure Ni to work — '737 deposits a Ni-based alloy, and '786's "nickel plating layer" is deployed with an alloyed (Zn-Ni) neighbor.
• The '690 specification itself treats the Ni-alloy alternatives as a mere listing ("Other suitable nickel alloys which may be deposited include NiFe, NiMn, NiMo, and NiSn") with no data distinguishing them and no asserted unexpected property for any particular species. A limitation that produces no disclosed difference in result is obvious where the species are known plating alloys (In re Merck & Co., 800 F.2d 1091 (Fed. Cir. 1986): "obvious to try" a limited class where no unexpected results).
• NiCo is specifically motivated by '690's own rationale (the parent '134's NiCo bath is conventional), and NiCo/NiFe plating baths were standard commercial products (the Nickel Institute review of nickel electroplating technology lists commercial Ni-alloy bath patents including zinc-nickel baths).
  → Claims 5, 7–11, 13–17 would be obvious as species within a disclosed genus, with no evidenced criticality.

3.4 Claim 6 — the gas-turbine-component product

Combination: US 5,595,831 + US 5,246,786 + US 4,786,377 (+ US 3,808,031).
Claim 6 differs from claim 1 by: (a) reciting a gas turbine engine component; (b) a low carbon steel substrate; (c) the Ni-alloy layer deposited "on and in contact with" the substrate; and (d) calling the first layer a "nickel alloy."

• (a) -> '831 (turbine corrosion protection) and '031 (diffusion coatings on gas-turbine hardware).
• (b) -> '031 expressly ("low carbon steels").
• (c) "on and in contact with" is the inherent geometry of '786's structure ('786: Ni layer "formed on said steel substrate") — no additional inventive content.
• (d) -> '737's Ni-alloy deposit; plus routine Ni-alloy plating (§3.3).
  The motivation is the same as §3.1, reinforced by '831's identification of turbines as a specific corrosion-protection market where cadmium-free Zn/Ni chemistries are desired.

3.5 Claim 12 — the method

Combination: US 5,246,786 + US 4,786,377 + US 5,595,831.
Claim 12's four steps are, element for element, the routine sequence already practiced in the art:

1. Provide low-carbon steel substrate — '786 (steel substrate) + '031 (low-carbon steel).
2. Form a nickel-alloy coating layer — '786 (Ni layer; and the field generally, via '737's Ni-alloy).
3. Apply a zinc layer over the Ni-alloy layer — '786 (Zn on Ni).
4. Diffuse the Zn into the Ni-alloy layer — '6377 (successive layers → solid-state diffusion) and '031 (successive deposition → diffusion for multi-metal corrosion coatings); also the Corronizing practice in §5 (Ni + Zn electroplate then heat-treat to interdiffuse).

Motivation: '786 supplies the why (combined heat + corrosion on steel); '6377 supplies the how (diffuse successive plated layers); '831 supplies the where (turbine components). No step in claim 12 is missing from the art, and no step requires anything beyond ordinary skill (the specification's own 600–800 °F/≥100 min diffusion is conventional heat-treat practice for Ni–Zn interdiffusion — see §5's Corronizing data of 700–800 °F for 20–60 min).

3.6 The unclaimed conversion-coating subject matter (context only)

Because the phosphated trivalent chromium conversion step is not in any of the 17 claims (as noted in the previously generated summary), the examiner-cited US 6,040,054 and US 6,527,841 (Navy trivalent-Cr post-treatment for metal-coated substrates) do not figure in the §103 analysis of the issued claims. They would only matter if one were attacking the specification's broader disclosure or a hypothetical broader claim. I flag this so the analysis is not over-read: the conversion chemistry is a distinguishing feature that was deliberately left out of the claims, which is itself a signal that the applicants/applicant's agent recognized the claimable line at the diffusion stack.

4. Secondary considerations and the counterarguments a patent owner would raise

A complete §103 analysis must weigh objective evidence (Graham factor 4). The record here gives the owner only limited ammunition.

5. Background art located in the search that is not on the patent's face (flagged separately)

While verifying the citations, the search surfaced a 1950s U.S. Air Force technical report, WADC TR 54-209, describing the commercial "Corronizing" process (Standard Steel Spring Co.): nickel and zinc (or tin/cadmium) are electroplated in succession and then given a controlled heat treatment which "converts the layers into a 'Corronized Coating,'" i.e., "a rather complete interdiffusion and alloying of the nickel with the other metal in the plated deposit." Reported properties: "good protection against corrosion and oxidation up to temperatures of 700 to 1000 °F"; "for the nickel-zinc combination, the heating is at 700 to 800 °F for 20 minutes to one hour"; and it is "being used on discs and spacers in gas turbines" and tested on aircraft engine cylinders.
Source: https://digital2.library.iit.edu/files//original/ff6e0dd28ffe81e7a8b5ef91c10737416b5fbe86.pdf (WADC TR 54-209, §§5)

Why this matters enormously to the §103 analysis: "Corronizing" is a printed publication (1955 government technical report) that is §102(b) art and that independently discloses the core of claims 1, 3, and 12 — a Ni-then-Zn electroplated bilayer on steel, thermally interdiffused, for combined corrosion and heat protection, above 900 °F, on gas-turbine hardware. If it were added to the combination, claims 1, 3, and 12 would be very difficult to defend. I flag it as outside the page's prior-art list, so it is not part of the "combine these references" answer you asked for, but it is the closest thing to a knockout reference and a competent searcher would have found it.

(I also encountered US 4,282,073 and US 4,351,713, Thomas Steel Strip Corp. "Electro-co-deposition of corrosion resistant nickel/zinc alloys onto steel substrates," and US 4,896,627 "Heat and corrosion resistant plating" — none of these are on the '690 citation list, and I did not fully verify them; treat as leads, not as-established art.)

6. Contradictions, ambiguities, and limits I want to flag explicitly

1. Two variants of the US 5,246,786 abstract appear in the search corpus. The granted claims and the FreePatentsOnline/EveryPatent abstracts recite "a zinc plating layer formed on said nickel plating layer," but a related Usui-family document (US 5,422,192, Takahashi) describes an intermediate "Zn–Ni alloy plating layer." Under the strict no-auto-correction rule, I use the granted-claim language of '786 ("zinc plating layer") and note the discrepancy rather than reconciling it. This is a real caveat: if the operative '786 actually claims an alloyed intermediate layer, the "separate Zn layer" element of claims 1/6/12 is less cleanly met by '786 alone (though '6377's successive-layer-deposition teaching still supplies it).
2. I could not fully verify US 4,859,289, US 5,176,812, US 5,300,401, US 5,330,850, US 5,494,706, US 6,040,054, or US 6,500,565 within the search budget. I therefore rely on their titles, dates, and classification, and do not assert specific disclosures for them. The analysis does not depend on them.
3. The "Similar Documents" list is contaminated with post-2002 documents (e.g., WO 2011/127473, EP 2 784 188 A1, 2014). These cannot be used against '690. Any analysis that (mis)uses them would be legally wrong. I flag this because the page layout invites the error.
4. The corronizing document (WADC TR 54-209) is offered as supplementary background, not as part of the combination, because it is not on the page's prior-art list and its exact publication/accessibility date I have not independently authenticated to the level a litigation contention would require.
5. This is a technical §103 assessment, not a legal opinion. Claim construction of "diffused therein" (particularly whether claim 1's recitation of both a separate "second layer… zinc" and zinc "diffused therein" is internally consistent with the specification's description of a single graded layer) could materially change the scope and thus the art mapping. That issue is a §112/claim-construction question, not §103, and I do not resolve it here.

7. Bottom line

Claims 1, 6, and 12 are prima facie obvious over the following combinations:

• Claim 1: US 5,246,786 (Ni layer on steel + Zn layer on Ni for combined heat/corrosion protection) in view of US 4,786,377 (successive electroplated layers on steel then solid-state diffusion to form an alloy), optionally with US 4,416,737 (Ni–Zn alloy on steel for corrosion resistance, chromate-post-treated). Motivation: '786 expressly states the unmet need for simultaneous heat + corrosion resistance; '6377 supplies the known technique of interdiffusing successive plated layers, a predictable modification with no change in principle of operation.
• Claim 6: the above combination in view of US 5,595,831 and US 3,808,031, which supply the gas-turbine context and the low-carbon-steel substrate for diffusion coatings.
• Claim 12: US 5,246,786 + US 4,786,377 + US 5,595,831 — the method steps are the routine electroplate/overplate/diffuse sequence, each element disclosed and each step within ordinary skill.
• Dependent claims 2–5 and 7–11 and 13–17 add only context (turbine hardware), inherent results of interdiffusion (two-way Ni/Zn diffusion), and a list of known nickel-alloy plating species with no disclosed criticality or unexpected result — all obvious as species election within a disclosed genus.

The strongest single-reference threat is not on the patent's citation list and should be investigated: the 1950s "Corronizing" art (Ni + Zn electroplated in succession, then heat-treated to interdiffuse on steel, for 700–1000 °F corrosion/oxidation protection, used on gas-turbine discs and spacers). If authenticated, it converts the §103 case against claims 1, 3, and 12 from "strong" to "compelling."

The patent's best defense is not the claim structure (which is thin and process-parameter-free) but a showing of unexpected results with a proper nexus — comparing the diffused coating against '786's layered Ni/Zn + chromate coating, rather than the patent's own NiCo-vs-NiCo+Zn comparison — and any evidence of long-felt need not already recognized in '786. On the current record, that showing has not been made.