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Surface Preparation of Nickel-Tungsten Alloys before Application of Metal Aluminide Bisque Coatings

IP.com Disclosure Number: IPCOM000124745D
Publication Date: 2005-May-05
Document File: 2 page(s) / 31K

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Surface Preparation of Nickel-Tungsten Alloys before Application of Metal Aluminide Bisque Coatings

Ion Transport Membranes (ITMs) are non-porous, ceramic membranes that are made from mixed metal oxides that conduct oxygen ions and electrons at elevated temperatures.  These materials have been proposed for two primary applications involving oxygen.  The first is the separation of oxygen from an oxygen-containing gas, such as air, to produce an oxygen product.  Oxygen can be recovered at high temperatures by passing the hot gas over the ITMs utilizing an oxygen partial pressure differential across the membrane to cause oxygen ions to migrate through the membrane.  The second application provides oxygen to an oxidation reaction, such as a partial oxidation of methane to form synthesis gas, in a single step that does both the separation and the reaction.

Membranes can be fabricated as tubes or flat plates that are arranged in modules for efficient contact with the hot, compressed air.  High-purity oxygen permeate and nitrogen-enriched, non-permeate products are withdrawn from the modules.  A comprehensive review of ion transport membranes for oxygen production is given by J. D. Wright and R. J. Copeland in Report No. TDA-GRI-90/0303 prepared for the Gas Research Institute, September 1990.

Synthesis gas, a mixture of hydrogen and carbon monoxide, can be produced by oxidatively reforming a hydrocarbon-containing stream, which passes on one side of an ion transport membrane, with oxygen from a hot, oxygen-containing gas, preferably air, which passes on the other side of the ITM.  This separation utilizes an oxygen chemical potential gradient across the membrane to cause oxygen ions to migrate through the membrane.

For synthesis gas production, membranes can be fabricated as tubes or flat plates that are arranged in modules for efficient contact with the hot air and hydrocarbon-containing streams.  Synthesis gas and nitrogen-enriched, non-permeate products are withdrawn from the modules.  A comprehensive review of ion transport membranes for synthesis gas production is given by M. Stoukides in Catalysis Reviews - Science and Engineering, 42(1&2), 2000.

The high-temperature operation of these membranes requires appropriate metallurgies that can provide the required mechanical strength at these conditions.  However, these meta...