Dense Compound Particles for Uniform Shaping and Sintering
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Solution Overview
Problem
Existing methods for producing feedstock compound particles for additive manufacturing, such as spray-drying and freeze-drying, are energy-intensive, produce porous and brittle particles, and result in inhomogeneous distributions of sinterable material and binder, which are disadvantageous for building dense and uniform parts.
Innovation Solution
Compound particles comprising pulverulent non-organic particles in a temporary organic binder with specific density, shape, and distribution characteristics are produced, ensuring high apparent density, smooth surfaces, and homogeneous distribution, achieved through a process that minimizes energy consumption and avoids mechanical comminution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If spray-drying or freeze-drying processes are used to produce feedstock compound particles, then particles can be obtained with rounded shape and flowability, but the processes are energy-consuming and produce porous and brittle particles with inhomogeneous distribution
Solution Approach 1:
The invention employs phase transition of the binder from solid to liquid state through heating to a temperature above its melting point, enabling the formation of dense particles without energy-intensive spray-drying or freeze-drying processes. The molten binder acts as a binding medium that consolidates particles into dense agglomerates with rounded shapes, achieving flowability without creating porous structures.
2Shape
If spray-drying or freeze-drying processes are used to produce feedstock compound particles, then particles can be obtained with rounded shape, but the particles are porous and brittle
Solution Approach 1:
The invention changes the temperature parameter to above the binder's melting point, transforming the binder into a liquid state that enables dense particle formation. This parameter change eliminates the porous and brittle characteristics associated with spray-drying and freeze-drying, producing particles with uniform density and improved mechanical strength while maintaining rounded shapes.
3Ease of manufacture
If spray-drying or freeze-drying processes are used to produce feedstock compound particles, then particles can be obtained, but the distribution of sinterable material and binder is inhomogeneous
Solution Approach 1:
The invention replaces mechanical comminution and drying processes with a thermal-melting approach. By heating the particle bed to melt the binder, the process achieves homogeneous distribution of sinterable material and binder throughout the particles. The molten binder naturally distributes evenly, eliminating the inhomogeneity problems caused by spray-drying and freeze-drying mechanisms.
4Ease of manufacture
If mechanical comminution is used to produce particles, then particles can be obtained, but particles with rounded shape and smooth surfaces cannot be achieved
Solution Approach 1:
The invention uses phase transition of the binder to liquid state through melting, which enables particles to form rounded shapes with smooth surfaces. The molten binder acts as a lubricant and binding agent during particle formation, creating smooth surfaces without the rough, fractured surfaces characteristic of mechanically comminuted particles.
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
The resulting particles exhibit low porosity, high stability, and uniform sintering properties, leading to dense and distortion-free green parts with improved flowability and mechanical strength.
Implementation Method 1
The compound particles are fed to a laser beam, wherein the organic binder melts when exposed to the laser radiation
Implementation Method 2
powdered metal which is free of binder is sintered by the scanning of a high-power laser beam
Implementation Method 3
the metal powder sintered
Implementation Method 4
binder-coated metal powders have been shaped by additive manufacturing
Implementation Method 5
The drying or sublimation step is carried out such that the solvent partially or completely transitions into the gas phase
Implementation Method 6
The drying or sublimation step is carried out such that the solvent partially or completely transitions into the gas phase
Data Source
AI summary
A plurality of compound particles for use in a shaping and sintering process, comprising pulverulent non-organic particles in a temporary organic binder, is characterized in that: (i) at least 80% of the pulverulent non-organic particles have a maximum dimension Amax in the range of from 10 nm to 500 μm, (ii) the amount of the temporary organic binder ranges from about 1 to 99 vol.-%, based on the total volume of the compound particles, (iii) at least 80% of the compound particles have a maximum dimension Bmax in the range of from 10 μm to 1000 μm, (iv) the compound particles have an apparent density of at least 70% of the true density, and (v) the compound particles have continuous external surfaces formed from pulverulent non-organic particles exposed at the external surfaces and temporary organic binder in the interstices between the pulverulent non-organic particles, the temporary organic binder presenting non-fractured surfaces. A process for preparing compound particles for use in a shaping and sintering process, comprises 1) providing a liquefied dispersion of pulverulent non-organic particles dispersed in a liquefied temporary organic binder, wherein at least 80% of the pulverulent non-organic particles have a maximum dimension Amax in the range of from 10 nm to 500 μm, 2) atomizing the liquefied dispersion to obtain atomized droplets, at least 80% of the atomized droplets having a maximum dimension B′max in the range of from 10 μm to 1000 μm, and 3) allowing the atomized droplets to solidify to obtain the compound particles.