PTAB

IPR2016-01289

General Electric Co v. United Technologies Corp

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Bond Coat for Silicon Based Substrates
  • Brief Description: The ’360 patent describes a multi-layer coating system for protecting silicon-based substrates used in high-temperature environments, such as gas turbine engines. The system comprises a silicon-based substrate, a bond layer made of a refractory metal disilicide/silicon eutectic alloy, and an outer environmental barrier layer composed of either barium-strontium aluminosilicate (BSAS) or yttrium silicate.

3. Grounds for Unpatentability

Ground 1: Obviousness over Terentieva and Eaton 456 - Claims 1-14

  • Prior Art Relied Upon: Terentieva (Patent 5,677,060) and Eaton 456 (Patent 6,387,456).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Terentieva discloses the core limitations of claim 1: a silicon-based substrate with a protective bond layer comprising a refractory metal disilicide/silicon eutectic alloy (specifically mentioning Ti-Mo-Si systems). During prosecution of the ’360 patent, claims directed to this structure alone were rejected as anticipated by Terentieva. The patent was allowed only after adding the limitation of a specific environmental barrier layer. Petitioner asserted that Eaton 456 explicitly teaches applying a BSAS environmental barrier layer to silicon-containing substrates (including molybdenum-silicon alloys) to protect them from high-temperature, aqueous environments. Therefore, the combination of Terentieva's bond coat with Eaton 456's barrier layer renders the claims obvious. For the dependent claims, Petitioner contended that Terentieva's disclosed coating inherently meets the recited properties, such as specific refractory metals (claims 2-3), high melting points (claim 4), multiphase microstructures (claims 5, 7, 9), and high silicon content (claims 11-14).
    • Motivation to Combine: A person of ordinary skill in the art (POSITA) would have recognized that the silica-forming layers taught in Terentieva are vulnerable to degradation from water vapor in high-temperature environments, a well-known problem in the art. Eaton 456 provides a known solution to this exact problem by teaching the use of a BSAS barrier layer. A POSITA would combine the teachings to improve the durability and longevity of Terentieva's coating system for its intended use in gas turbine engines.
    • Expectation of Success: Petitioner argued a POSITA would have a reasonable expectation of success because the prior art taught that BSAS was compatible with the underlying silicon-containing materials disclosed in Terentieva. Eaton 456 specifically teaches that its BSAS barrier layer is compatible with molybdenum-silicon alloys and that the coefficient of thermal expansion (CTE) of the barrier layer and substrate can be matched, ensuring stability.

Ground 2: Obviousness over Terentieva, Webster, Suzuki, and Admitted Prior Art - Claims 1-14

  • Prior Art Relied Upon: Terentieva (Patent 5,677,060), Webster (a 1998 journal article on yttrium silicate coatings), Suzuki (a 1998 journal article on MoSi2 properties), and Admitted Prior Art within the ’360 patent specification.
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addresses the second option for the environmental barrier layer in claim 1: yttrium silicate. As in Ground 1, Terentieva was asserted to teach the substrate and the refractory metal disilicide/silicon eutectic bond layer. Petitioner argued that the ’360 patent itself, in its "Background of the Invention" section, identifies yttrium silicate as a known prior art environmental barrier layer for silicon-based substrates. This admission, combined with technical support from Webster and Suzuki, allegedly makes the combination obvious. Webster discloses that yttrium silicate is a suitable outer coating for protecting SiC-containing materials at high temperatures. Suzuki demonstrates the chemical compatibility of yttria silicates with molybdenum disilicide (MoSi2), a key component of the bond coat in Terentieva.
    • Motivation to Combine: The motivation is parallel to Ground 1: to protect the vulnerable silica-forming layers of Terentieva's coating from water vapor attack. The motivation is reinforced by the ’360 patent's own admission that yttrium silicate was a known environmental barrier layer, indicating it was a recognized option for a POSITA seeking to solve this known degradation problem.
    • Expectation of Success: A POSITA would have expected success because Webster and Suzuki explicitly teach the compatibility of yttrium silicate with the types of materials used in Terentieva's bond coat (SiC-containing materials and MoSi2). This established chemical and physical compatibility would provide a strong basis for successfully applying a yttrium silicate barrier layer to the Terentieva system.

4. Key Claim Construction Positions

  • "refractory metal disilicide/silicon eutectic": Petitioner proposed this term be construed as "a material that includes a high melting point metal disilicide and silicon as a combination of phases." This construction was intended to be broad enough to encompass the multiphase microstructures described in the prior art, particularly Terentieva, which describes a refractory phase (disilicide) and a healing phase formed by a eutectic of unbound silicon.
  • "bond layer": Petitioner proposed this term be construed as "any layer located between at least two other layers or between the substrate and another layer." This construction, supported by the specification and prosecution history, ensures that the coating taught by Terentieva, which lies between the substrate and a potential outer oxide film, functions as the claimed bond layer.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-14 of Patent 7,060,360 as unpatentable.