Metal Powders: From Rheology to the Performance of Engineered Materials
What Is Additive Manufacturing?
Complementary to traditional manufacturing processes based on material removal, additive manufacturing now makes it possible to benefit from unmatched design freedom and exceptional implementation speed. It meets the needs of many applications in highly demanding markets such as aerospace, medical, space, defense, and more.
Additive manufacturing consists of building a part by successive layers of powder, most often metal, fused by a beam (laser or electrons, for example).
The FILAB laboratory is ISO 17025 accredited by COFRAC for:
- specific surface area measurement using the BET method (according to ISO 9277) and particle size analysis by laser diffraction (according to ISO 13320 in liquid and dry media),
- density measurement by helium pycnometry (according to ASTM B923 and ISO 12154),
- grain size determination (according to ASTM E112 and NF EN ISO 643) for bulk materials.
Analysis of Metal Powders: Why Work with FILAB?
With significant experience in implementing these different techniques, FILAB supports you with your metal powder analysis needs and the expertise associated with additive manufacturing activities:
Chemical composition analysis of metal powders by ICP-AES, ICP-MS and/or by elemental analyzers for C/S, O/N, H...
Density measurement according to ASTM B527, ISO 3953,
Particle size analysis by laser diffraction according to ISO 13320
Flowability measurement according to ASTM B213, ISO 4490, ASTM B964,
Morphological analysis by SEM-FEG EDX or Optical Microscopy
SAFRAN approval according to specification Ma0015. SAFRAN has expanded the scope of our approval to include the chemical and physical characterization of metal powders! This recognition once again highlights our expertise in characterization and analysis of metal powders, enabling us to respond more quickly and reliably to our clients’ needs.
Instruments for Metal Powder Analysis:
GranuHeap : measurement of the static properties of a metal powder (angle of repose, static cohesion index).
GranuDrum : measurement of the flow properties (flow angle, dynamic cohesion index, first avalanche angle, powder aeration).
GranuPack : measurement of the dynamic compaction of a metal powder (bulk density, tapped density, Hausner ratio, densification dynamics).
GranuFlow : measurement of flow through orifices, a key indicator of powder flowability.
GranuCharge : measurement of the electrostatic properties of metal powders.
Why Characterize Your Metal Powders?
This manufacturing process is sensitive to variations in the size and shape of the metal powder particles used as raw material or recycled material. Indeed, these geometric characteristics determine in particular how the powder spreads during the process, as well as its level of compaction, which helps limit voids.
To ensure the quality of the parts produced, metal powders must therefore meet many requirements in order to achieve the expected performance. Included in particular in standard NF E 67-010, which sets out the technical specifications for metal powders for additive manufacturing applications, the parameters regularly assessed are:
- particle size distribution generally measured by laser diffraction particle sizing according to ISO 13320, which provides access to the particle size distribution with determination of characteristic parameters (d10, d50, d90),
- flowability characterized by a flow time using a calibrated funnel of the Hall flowmeter type according to ISO 4490 and ASTM B 213 or the Carney funnel according to ASTM B 964,
- bulk density and tapped density used to characterize, through mechanical action, a powder’s ability to pack by expelling air between the grains. These tests are carried out using a tapped density tester according to ASTM B 527 and ISO 3953. The Hausner ratio corresponds to the ratio of tapped density to bulk density,
- true density determined by pycnometry according to ISO 12154 or ASTM B 923. This parameter makes it possible, in particular, to calculate the internal porosity rate using the theoretical density (of a bulk material, for example),
- morphology assessed by Scanning Electron Microscopy (SEM-FEG) and Optical Microscopy to evaluate particle size and morphology, sphericity, satelliting (small-diameter powder agglomerated onto large-diameter powder for recycled materials),
- moisture content determined gravimetrically after drying according to ASTM E 1868,
- chemical composition of metal powders. It is determined by spectroscopic techniques such as ICP-AES and ICP-MS and by elemental analysis techniques after combustion for the quantification of C, S, N, O and H elements.
Compliance with the requirements associated with these different characteristics enables the metal powder to produce, in the manufactured part, a low defect rate (porosity, inclusion, etc.) and a high level of compactness, synonymous with excellent mechanical properties.
