GB/T 3249-2022 in English
VALIDTest method for Fisher number of metal powders and related compounds
- Issued on:2022-03-09
- Implemented on:2022-10-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
$175.00
《GB/T 3249-2022金属及其化合物粉末费氏粒度的测定方法》由TC243（全国有色金属标准化技术委员会）归口，TC243SC4（全国有色金属标准化技术委员会粉末冶金分会）执行，主管部门为中国有色金属工业协会。
Introduction
Core changes in the standard revision
| Technical elements | 2009 edition | 2022 edition | Significance of the revision |
|---|---|---|---|
| Posity classification | 15.0μm~20.0μm single range | Divided into 0.40~0.55 and>0.55~0.80 two ranges | Improve the measurement accuracy of large particles |
| Instrument calibration | Single calibration | Calibration every 4 hours + temperature monitoring | Ensure data stability |
| Sample processing | No clear dispersion requirements | GB/T37561 dispersion standard is cited | Regulate the processing of agglomerated samples |
Analysis of key technologies
1. Determination principle
Based on the air permeability method, the air permeability of the powder layer is measured by a Fischer particle size analyzer, and the equivalent spherical diameter is derived after converting the external specific surface area. Core formula:
dvs = 60000c × [F/((ALρ-M)(PF))]1/2
Key parameters in the formula: air viscosity η, needle valve conductivity C, and powder true density ρ must be strictly calibrated.
2. Key components of the instrument
- Ruby standard tube: Aperture calibration error ≤1%, monthly cleaning and maintenance required
- Sample tube: Inner diameter 12.70mm±0.05mm, scrapped if worn out of tolerance
- Pressure gauge: After zeroing the water level, it needs to be left to stand for 15 minutes before calibration
Operation specification points
1. Sample preparation
Perform dispersion treatment according to GB/T37561 to eliminate agglomeration effect. The sample volume must be ≥2 times the true density value (e.g., if the true density of tungsten powder is 19.3g/cm³, the sample should be ≥38.6g).
2. Calibration process
- Prioritize the low gear (0.5-20μm) and then switch to the high gear (20-50μm)
- The porosity pointer must be consistent with the nominal value of the ruby tube
- Read the particle size value after the pressure stabilizes. If the deviation exceeds ±1%, adjust the needle valve
3. Data validity judgment
Repeatability limit r=2%-6% of the measured value, reproducibility limit R=0.173dvs-0.042. Example: When dvs=10μm is measured, the difference between laboratories should be ≤1.688μm.
Comparison of the implementation of the new and old standards
Case: Tungsten Carbide Powder Testing
After the 2022 version adds porosity classification, the 15.0-20.0μm sample needs to select the corresponding scale according to the actual porosity to avoid the ±2μm error caused by the original single-grade measurement.
Implementation suggestions
- Establish a record of the use of ruby standard tubes and record the temperature and ambient humidity of each calibration
- For easily oxidized powders (such as titanium powder), it is recommended to operate in an inert gas environment
- Fibrous powders need to be negotiated to adopt a correction factor and cannot be directly applied to the standard
Loading PDF document...
Error loading PDF. Please make sure the file is valid and try again.
We also recommend
-
GB/T 3488.4-2022 in English
Hardmetals—Metallographic determination of microstructure—Part 4: Characterisation of porosity, carbon defects and eta-phase content
2022-10-12 -
GB/T 19076-2022 in English
Specifications for sintered metal materials
2022-03-09 -
GB/T 6883-2017 in English
Cemented carbide sintering body for wire, bar or tube drawing dies - Dimensions
2017-09-29 -
GB/T 5318-2017 in English
Sintered metal materials(excluding hardmetals)without notch impact test piece
2017-09-29 -
GB/T 41329-2022 in English
Determination of flow rate of metallic powders—Calibrated funnel method (Gustavsson flowmeter)
2022-03-09
