The United States of America As Represented by the United States

United Technologies Corporation

Carl K Johnson

Paul E Grevstad

Anthony P Mientek

Leonard J Bonville

Robert C Stewart, Jr

A method of forming thin, uniform braze joints is effected through the use of curtain coating. Braze powder is admixed with a liquid polymeric binder to form a slurry. The slurry is forced through the slots in a curtain coating head and deposited on at least one of the metal surfaces to be bonded together. The method has particular utility for bonding fin/plate sections of a heat exchanger where the fins have a U-shaped cross section. The slurry is deposited on the top portion of the fin and the side portion of the fin and wiped from the top portion leaving braze material primarily on the side wall portion. When the plates are contacted to the fins and heating performed, a bond is effected with maximum plate-to-fin contact for high heat transfer and a strong braze joint.

Uniform braze application process

A manifold-to-stack seal and sealing method for fuel cell stacks. This seal system solves the problem of maintaining a low leak rate manifold seal as the fuel cell stack undergoes compressive creep. The seal system eliminates the problem of the manifold-to-stack seal sliding against the rough stack surface as the stack becomes shorter because of cell creep, which relative motion destroys the seal. The seal system described herein utilizes a polymer seal frame firmly clamped between the manifold and the stack such that the seal frame moves with the stack. Thus, as the stack creeps, the seal frame creeps with it, and there is no sliding at the rough, tough to seal, stack-to-seal frame interface. Here the sliding is on a smooth easy to seal location between the seal frame and the manifold.

Method for producing a fuel cell manifold seal

Fuel cell manifold sealing system

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Manchester, CT, United States of America

Carl K Johnson