Porous Metal Articles With Extractable Particulate Pore Forming
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Solution Overview
Problem
Existing methods for manufacturing porous metal articles face challenges such as contamination, limited control over pore structure, and reduced strength, particularly in high-purity applications like orthopedic implants, due to issues with void former materials and processing techniques.
Innovation Solution
The method involves blending metal powder with extractable particulates to form a homogenous mixture, extracting the particulates using a fluid, and sintering the resulting metal matrix to create porous metal articles with tailored porosity, allowing for control over pore density, size, and interconnectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermal decomposition or vaporization methods are used to create porosity, then pore formation is achieved, but contamination of the metal matrix occurs and processing capabilities are limited
Solution Approach 1:
The patent extracts the harmful thermal decomposition process from the pore formation mechanism. Instead of using thermal vaporization that contaminates the metal matrix, the invention uses a cold extraction process where a pore-forming material is introduced, compacted with metal powder, and then extracted using a solvent or melting process at low temperatures, thereby removing the contamination source while maintaining pore structure control
Solution Approach 2:
The patent introduces an intermediary pore-forming material (such as wax, polymer, or salt) that mediates the pore formation process. This intermediary material can be easily extracted without reacting with or contaminating the metal matrix, unlike direct thermal decomposition methods. The intermediary serves as a temporary placeholder that defines pore geometry before being removed through benign extraction processes
2Manufacturing precision
If high pressure compaction and densification are applied, then metal densification is achieved, but the void former material deforms and pore properties cannot be tailored
Solution Approach 1:
The patent applies preliminary action by selecting pore-forming materials with appropriate mechanical properties before compaction. The pore-forming material is chosen to maintain its shape and size during the compaction process, preventing deformation. This preliminary selection ensures that the void structure remains intact throughout densification, allowing precise pore property tailoring while achieving metal matrix densification
Solution Approach 2:
The patent utilizes parameter changes by carefully controlling compaction pressure, temperature, and pore-forming material properties to achieve the desired balance. By adjusting these parameters, the metal matrix can be densely compacted while the pore-forming material maintains its geometric integrity, enabling precise control over final pore size and distribution after extraction
3Manufacturing precision
If plasma spray or vapor deposition is used to form porous layers, then porous structure is created, but bending strength is reduced and structural integrity is compromised
Solution Approach 1:
The patent merges the pore formation process with the metal matrix formation process by compacting pore-forming material and metal powder together in a homogeneous mixture before sintering. This integration ensures that the porous structure and metal matrix are formed simultaneously as a unified structure, optimizing both pore distribution and mechanical strength, unlike sequential deposition methods that create weak interfaces
4Manufacturing precision
If slurry deposition onto foam substrate is used, then porous coating is formed, but penetration and even coating are limited
Solution Approach 1:
The patent inverts the conventional approach by instead of depositing material onto a pre-formed foam substrate, it forms the porous structure and metal matrix simultaneously through co-compaction and co-sintering. This inversion eliminates the slurry penetration problem entirely, as the pore-forming material and metal powder are mixed and compacted together, ensuring uniform distribution and eliminating the need for slurry infiltration into foam pores
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
This approach enables the production of porous metal articles with controlled pore structures and enhanced strength, free from contamination, suitable for various applications including orthopedic implants, with precise tailoring of porosity and mechanical properties.
Implementation Method 1
extracting the particles using a fluid to form a metal matrix green article
Implementation Method 2
sintering the green article
Data Source
AI summary
A porous metal article having a predetermined pore structure. The porosity is provided by the use of an extractable particulate in a powder forming route to create a desired porosity. Extraction of the pore forming particulate prior to sintering of the powder minimizes contamination of the sintered article and allows for the processing of material sensitive to contamination such as titanium. Added functionality can be gained by co-forming the porous material with non-porous material to create an article with layers of differing characteristics. The article is suitable for use as an implant body is porous enough to facilitate tissue in-growth and bony fusion.