Powder-based material system with stable porosity

• US 9,186,866 B2
• Filed: 01/10/2012
• Issued: 11/17/2015
• Est. Priority Date: 01/10/2012
• Status: Active Grant

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Merrill, Gary B., Schillig, Cora
• Primary Examiner(s): Snelting, Erin
• Application Number:
  US13/346,767
• Publication Number:
  US 20130177740A1
• Time in Patent Office: 1,407 Days
• US Class Current: 1/1
• CPC Class Codes: B22F 3/1017 Multiple heating or additional steps B22F3/101 takes precedence
• CPC Class Codes: B22F 3/105 by using electric current other than for infrared radiant energy, laser radiation or plasma B22F3/11 takes precedence; by ultrasonic bonding B22F3/115 takes precedence
• CPC Class Codes: B22F 3/1112 comprising hollow spheres or hollow fibres
• CPC Class Codes: B22F 5/009 of turbine components other than turbine blades of turbine blades B22F5/04
• CPC Class Codes: B22F 7/002 of porous nature
• CPC Class Codes: B22F 7/008 characterised by the composition
• CPC Class Codes: B32B 2264/105 Metal
• CPC Class Codes: B32B 2264/107 Ceramic
• CPC Class Codes: B32B 2307/304 Insulating
• CPC Class Codes: B32B 3/26 characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids foam layer B32B5/18; layer of synthetic resin characterised by fillers that create voids or cavities B32B27/205; characterised by an apertured layer
• CPC Class Codes: B32B 5/30 one layer being formed of particles, e.g. chips, granules, powder
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C04B 2235/34 Non-metal oxides, non-metal mixed oxides, or salts thereof that form the non-metal oxides upon heating, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
• CPC Class Codes: C04B 2235/5436 micrometer sized, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/5454 nanometer sized, i.e. below 100 nm
• CPC Class Codes: C04B 2235/5472 Bimodal, multi-modal or multi-fraction
• CPC Class Codes: C04B 2235/666 Applying a current during sintering, e.g. plasma sintering [SPS], electrical resistance heating or pulse electric current sintering [PECS]
• CPC Class Codes: C04B 2235/9607 Thermal properties, e.g. thermal expansion coefficient
• CPC Class Codes: C04B 2237/343 Alumina or aluminates
• CPC Class Codes: C04B 2237/348 Zirconia, hafnia, zirconates or hafnates
• CPC Class Codes: C04B 2237/403 : Refractory metals
• CPC Class Codes: C04B 2237/405 : Iron metal group, e.g. Co or Ni
• CPC Class Codes: C04B 2237/64 : Forming laminates or joined articles comprising grooves or cuts
• CPC Class Codes: C04B 2237/704 : of one or more of the ceramic layers or articles
• CPC Class Codes: C04B 37/021 : in a direct manner, e.g. direct copper bonding [DCB]
• CPC Class Codes: Y10T 428/24496 : Foamed or cellular component
• CPC Class Codes: Y10T 428/24942 : including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/249969 : Of silicon-containing material [e.g., glass, etc.]

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.

Claims

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.

2. The method of claim 1, further comprising:

partially pre-sintering the substrate prior to the co-sintering;

performing the co-sintering by spark plasma sintering (SPS) while producing the mechanical pressure by compressing the substrate and the layer with an SPS electrode; and

wherein the hollow ceramic shapes comprise spheres selected or formed with a wall thickness relative to a diameter thereof, and are pre-sintered sufficiently to withstand the mechanical pressure without flattening the spheres to less than a 0.7 aspect ratio.

3. The method of claim 2, further comprising providing a volume fraction of the spheres that varies in the layer with distance from the substrate.

4. The method of claim 1, further comprising:

forming the substrate from a mixture of the metal powder and a binder that forms a metal/binder mixture;

forming a surface of the substrate that provides engineered interlocking surface features on the substrate; and

forming the layer by filling the interlocking surface features on the substrate with the ceramic powder to provide an interlock there between.

5. The method of claim 1, further comprising:

selecting the metal and ceramic materials to be a material couple from the set of material couples consisting of;

MoCu and Al₂O₃;

Ta and Al₂O₃; and

FeCrSi—

Y₂O₃ and 8 mol YSZ; and

applying a voltage across the layer and the substrate effective to produce the final density of the substrate and the final density of the layer by spark plasma sintering.

6. The method of claim 1, further comprising forming the substrate to further comprise a plurality of hollow shapes.

7. The method of claim 1, further comprising selecting and preparing the metal material, the ceramic material, the percentage of ceramic nano-particles, and a volume fraction of the hollow ceramic shapes such that the co-sintering produces respective shrinkage amounts of the layer and the substrate that are within 5% of each other throughout the co-sintering thereof.