Powder-based material system with stable porosity
First Claim
1. A method of fabricating a powder-based material system having stable porosity, comprising:
- selecting a metal material and a ceramic material with respective coefficients of thermal expansion that are within 15% of each other throughout an operating temperature range plus a co-sintering temperature range;
forming a substrate from a powder of the metal material;
arranging a layer on the substrate, wherein the layer comprises a powder of the ceramic material containing at least 1% by volume of ceramic nano-particles having an average diameter of less than 100 nm and a plurality of hollow ceramic shapes; and
co-sintering the substrate and the layer under mechanical pressure within the co-sintering temperature range effective to form a bond there between and to achieve a final density of the substrate and a final density of the layer providing a material system with a stable degree of porosity during subsequent operation in the operating temperature range.
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Abstract
A powder-based material system having an intrinsic and stable degree of porosity provided by hollow ceramic spheres (26) in a fully dense matrix (27). A substrate (22) is formed from a metal powder (70), and may be partially sintered (60). A layer (24) of ceramic powder is arranged on the substrate including the pre-sintered hollow ceramic spheres plus a proportion of nano-sized ceramic particles effective to reduce the layer sintering temperature and to increase the sintering shrinkage of the layer to approximate that of the metal substrate during subsequent co-sintering. The substrate and layer are then co-sintered (61), such as with spark plasma sintering (32, 34, 36), at a temperature and for a duration to fully densify the ceramic powder matrix around the hollow spheres, thereby producing a metal/ceramic material system with low interface stress and with stable porosity during operational temperatures in a gas turbine engine.
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Citations
7 Claims
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1. A method of fabricating a powder-based material system having stable porosity, comprising:
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selecting a metal material and a ceramic material with respective coefficients of thermal expansion that are within 15% of each other throughout an operating temperature range plus a co-sintering temperature range; forming a substrate from a powder of the metal material; arranging a layer on the substrate, wherein the layer comprises a powder of the ceramic material containing at least 1% by volume of ceramic nano-particles having an average diameter of less than 100 nm and a plurality of hollow ceramic shapes; and co-sintering the substrate and the layer under mechanical pressure within the co-sintering temperature range effective to form a bond there between and to achieve a final density of the substrate and a final density of the layer providing a material system with a stable degree of porosity during subsequent operation in the operating temperature range. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification