Sinterable Metal Paste for Additive Manufacturing
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Solution Overview
Problem
Current additive manufacturing techniques for metals, such as powder bed fusion, face challenges including expensive equipment, long process times, and inhomogeneous mechanical properties due to the use of coarse metal powders.
Innovation Solution
A metal paste formulation comprising a vehicle with a solvent and polymeric binder, metal scaffold particles, and metal infiltrant particles is used to create a layered body that can be easily sintered, resulting in a porous scaffold with infiltrant particles positioned in interstitial voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If coarse metal powders are used in powder bed fusion, then high mechanical strength can be achieved through melting, but expensive equipment and long process times are required
Solution Approach 1:
The patent changes the particle size parameter from coarse (5-30 micrometers) to fine metal particles (less than 10 micrometers), which fundamentally alters the sintering behavior and enables faster processing while maintaining mechanical strength through optimized particle packing and sintering kinetics
Solution Approach 2:
The patent utilizes sintering as a phase transition process where fine metal particles are heated to partially fuse and bond together, forming dense metal parts without complete melting. This phase transition approach with fine particles reduces processing time compared to melting coarse particles
2Strength
If coarse metal powders are used in powder bed fusion, then high mechanical strength can be achieved through melting, but equipment costs increase due to high power laser requirements
Solution Approach 1:
The patent changes the particle size parameter to fine metal particles (less than 10 micrometers), which have higher surface area and require lower laser power for sintering, thereby reducing equipment cost and complexity while maintaining mechanical strength through optimized sintering processes
Solution Approach 2:
The patent employs fine metal particles that can be processed with less expensive, lower power laser equipment. The fine particles enable a simpler, more accessible manufacturing approach compared to the high-power laser systems required for coarse particle melting
3Use of energy by moving object
If fine metal particles are used to reduce processing energy, then manufacturing cost decreases, but particle handling becomes difficult due to stickiness and clumping
Solution Approach 1:
The patent introduces a liquid vehicle as an intermediary medium to disperse fine metal particles, preventing their inherent stickiness and clumping. This slurry formulation enables easy handling and deposition of fine particles while maintaining their low processing energy advantage
Solution Approach 2:
The patent uses a liquid vehicle (hydraulic approach) to suspend and transport fine metal particles, overcoming their handling difficulties. The liquid medium provides fluidity and ease of operation while the particles retain their low energy processing characteristics
4Use of energy by moving object
If fine metal particles are used in additive manufacturing, then processing energy is reduced, but manufacturing precision becomes challenging due to particle handling difficulties
Solution Approach 1:
The patent uses a liquid vehicle as an intermediary to precisely deposit fine metal particles layer by layer. The liquid medium enables controlled dispensing and precise positioning of particles, overcoming handling difficulties while maintaining low processing energy and achieving high manufacturing precision
Solution Approach 2:
The patent applies fine metal particles in a controlled slurry form to specific locations with precise positioning. The local deposition approach, enabled by the liquid vehicle, ensures manufacturing precision while utilizing the energy-efficient fine particle characteristics
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 method enables high-rate and high-resolution metal part production with improved mechanical and processing benefits, including reduced porosity and enhanced mechanical strength, while minimizing equipment costs and processing time.
Implementation Method 1
The state of the art in additive manufacturing of metals is the laser melting or sintering of coarse metal powders in a technique typically called 'powder bed fusion' (PBF). Subsequently, a high powered laser is moved across the powder bed, only exciting selected regions which melt into the desired shape for a layer.
Data Source
AI summary
A material and method are disclosed such that the material can be used to form functional metal pieces by producing an easily sintered layered body of dried metal paste. On a microstructural level, when dried, the metal paste creates a matrix of porous metal scaffold particles with infiltrant metal particles, which are positioned interstitially in the porous scaffold's interstitial voids. For this material to realize mechanical and processing benefits, the infiltrant particles are chosen such that they pack in the porous scaffold piece in a manner which does not significantly degrade the packing of the scaffold particles and so that they can also infiltrate the porous scaffold on heating. The method of using this paste provides a technique with high rate and resolution of metal part production due to a hybrid deposition/removal process.