Thermal spraying - Powders - Part 1: Characterization and technical supply conditions
1Key Takeaways
This document specifies measurement methods for characterizing powders and their technical supply status. It applies to powders used in thermal spraying based on their physical and chemical properties.
2Expert Interpretation
This article provides an in-depth interpretation of ISO 14232-1:2017, the international standard for thermal spray powders, covering methods for determining key parameters such as powder chemical composition, particle size distribution, and apparent density. It also compares the effects of different manufacturing processes on powder morphology and provides powder selection recommendations for specialized spray processes such as HVOF.
Interpretation of the Standard's Core Content
ISO 14232-1:2017, an international standard for thermal spray powders, systematically specifies testing methods and technical supply requirements for the physical and chemical properties of powders. This standard applies to metallic and non-metallic spray powders measured using instruments such as ICP-OES and laser scattering.
Key property requirements of powder
| Test items | Test standard | Permissible deviation | Typical instrument |
|---|---|---|---|
| Particle size distribution | Sieving method/Laser scattering method | Upper limit ≤10% (Sieving) or ≤25% (Laser) | Air jet sieve, Malvern particle size analyzer |
| Apparent density | ISO 3923-2 | ±0.2 g/cm³ | Scott volume meter |
| Flowability | ISO 4490 | Non-free flowing powders require special marking | Hall flow meter |
Technology evolution and implementation recommendations
Particle size control case:For the HVOF process, the standard requires special attention to the content of fine powder below 5μm (≤1%). This type of powder is prone to clogging the nozzle. It is recommended to use the laser scattering method in combination with an electron microscope for morphology analysis.
Influence of manufacturing process: Gas atomized (GAT) powders generally have a higher sphericity (as shown in Figure A.4), while sintered (S) powders exhibit a porous structure (Figure A.6), which directly affects the density and bonding strength of the coating.
Supply conditions and specifications
The standard mandates that powder packaging be labeled with a "mix thoroughly before use" warning and provide an inspection certificate in accordance with ISO 10474. For cemented carbide powders such as WC-Co, the certificate must include phase composition analysis (EDX or XRD results).