Metal Matrix Composite Sheet Forming for Thin-Wall Complex Shapes
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Solution Overview
Problem
Fabrication of hard alloy or metal matrix composite articles with complex geometry and thin wall structure/thin cross-section is challenging due to brittleness and limitations in existing methods like powder pressing, extrusion, and casting, which often require significant additional processing.
Innovation Solution
A method involving a temporary substrate with a layered assembly of infiltration metal/alloy and hard particles bound by an organic binder, where the assembly is heated to infiltrate the hard particle layer, forming a freestanding metal matrix composite or sintered alloy article, allowing for near-net shape production without the constraints of traditional techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pre-forming by powder pressing, extrusion or injection molding followed by sintering is used, then articles can be produced with controlled geometry, but tooling and die limitations prevent near-net shape production and require additional significant green shaping, machining and processing
Solution Approach 1:
The invention extracts the hard particles from the conventional powder metallurgy process and places them on a flexible support sheet before infiltration. This removes the limitation of rigid tooling and dies, allowing the article geometry to be defined by the flexible sheet rather than constrained by mold cavities, thereby enabling near-net shape production of complex geometries
Solution Approach 2:
The invention transitions from a conventional three-dimensional mold cavity approach to a two-dimensional flexible sheet approach. The flexible support sheet with hard particles disposed thereon can be conformally shaped and then infiltrated, allowing complex three-dimensional geometries to be achieved through the flexibility and conformability of the two-dimensional sheet structure
2Shape
If casting is used for making articles of complex geometry and thick wall structure, then articles can be produced with complex geometries, but the method is mainly limited to a subset of metal and alloy systems suitable for casting and is difficult for hard alloys and metal matrix composites
Solution Approach 1:
The invention uses a composite structure consisting of a flexible support sheet with hard particles disposed thereon, which is then infiltrated with metal or alloy. This composite approach allows the flexible sheet to provide the desired complex geometry while the infiltration metal provides the structural integrity, enabling the production of hard alloys and metal matrix composites that would be difficult to cast
Solution Approach 2:
The invention segments the final article into two components: the flexible support sheet that defines the geometry and the infiltration metal that provides the material properties. This segmentation allows independent optimization of geometry (through the flexible sheet) and material selection (through the infiltration metal), thereby expanding adaptability to various metal and alloy systems including hard alloys and metal matrix composites
3Length of moving object
If mechanical working, such as hot rolling, is employed for making thin metal or alloy sheets, then thin sheets can be produced, but hard alloys and metal matrix composites are generally unsuitable due to high hardness rendering them brittle and prone to crack formation
Solution Approach 1:
Instead of mechanically working the hard alloy or metal matrix composite to make it thin (which causes brittleness and cracking), the invention inverts the approach by first creating a flexible support sheet with the desired thin geometry, disposing hard particles on it, and then infiltrating with metal. This allows thin-walled structures to be produced without subjecting the hard material to mechanical working that would cause cracking
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the production of fully dense, freestanding composite or metallic articles with complex geometries and thin walls, reducing the need for extensive processing and overcoming brittleness issues, while allowing for large sizes and improved mechanical and wear properties.
Implementation Method 1
The layered assembly is heated to infiltrate the hard particle layer with the metal or alloy providing a metal matrix composite
Implementation Method 2
The sheet of organic binder and powder metal or powder alloy is heated to provide a sintered metal or sintered alloy article
Data Source
AI summary
In one aspect, methods of making freestanding metal matrix composite articles and alloy articles are described. A method of making a freestanding composite article described herein comprises disposing over a surface of the temporary substrate a layered assembly comprising a layer of infiltration metal or alloy and a hard particle layer formed of a flexible sheet comprising organic binder and the hard particles. The layered assembly is heated to infiltrate the hard particle layer with metal or alloy providing a metal matrix composite, and the metal matrix composite is separated from the temporary substrate. Further, a method of making a freestanding alloy article described herein comprises disposing over the surface of a temporary substrate a flexible sheet comprising organic binder and powder alloy and heating the sheet to provide a sintered alloy article. The sintered alloy article is then separated from the temporary substrate.