ASTM B430-97(2001)
(Test Method)Standard Test Method for Particle Size Distribution of Refractory Metal Powders and Related Compounds by Turbidimetry
Standard Test Method for Particle Size Distribution of Refractory Metal Powders and Related Compounds by Turbidimetry
SCOPE
1.1 This test method covers the determination of particle size distribution of refractory metal powders with a turbidimeter (1). Experience has shown that this test method is satisfactory for the analysis of elemental tungsten, molybdenum, rhenium, tantalum metal powders, and tungsten carbide powders. Other refractory metal powders, for example, elemental metals, carbides, and nitrides, may be analyzed using this test method with caution as to significance until actual satisfactory experience is developed. The procedure covers the determination of particle size distribution of the powder in two conditions:
1.1.1 As the powder is supplied (as-supplied), and
1.1.2 After the powder has been de-agglomerated by rod milling (laboratory milled) according to Practice B859.
1.2 Where dual units are given, inch-pound units are to be regarded as standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
Designation:B430–97 (Reapproved 2001)
Standard Test Method for
Particle Size Distribution of Refractory Metal Powders and
Related Compounds by Turbidimetry
This standard is issued under the fixed designation B 430; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope E 456 Terminology Relating to Quality and Statistics
E 691 Practice for Conducting an Interlaboratory Study to
1.1 This test method covers the determination of particle
Determine the Precision of a Test Method
size distribution of refractory metal powders with a turbidime-
ter (1). Experience has shown that this test method is
3. Summary of Test Method
satisfactory for the analysis of elemental tungsten, molybde-
3.1 Auniform dispersion of the powder in a liquid medium
num, rhenium, tantalum metal powders, and tungsten carbide
is allowed to settle in a glass cell. A beam of light is passed
powders. Other refractory metal powders, for example, el-
through the cell at a level having a known vertical distance
emental metals, carbides, and nitrides, may be analyzed using
from the liquid level. The intensity of the light beam is
this test method with caution as to significance until actual
determined using a photo cell. This intensity increases with
satisfactory experience is developed. The procedure covers the
time as sedimentation of the dispersion takes place.
determination of particle size distribution of the powder in two
3.2 The times at which all particles of a given size have
conditions:
settled below the level of the transmitted light beam are
1.1.1 As the powder is supplied (as-supplied), and
calculated from Stokes’ law for the series of sizes chosen for
1.1.2 After the powder has been de-agglomerated by rod
the particle size analysis.
milling (laboratory milled) according to Practice B 859.
3.3 The intensity of the light beam at these times is
1.2 Where dual units are given, inch-pound units are to be
measured as percent of the light transmitted through the cell
regarded as standard.
with the clear liquid medium. The size distribution in the
1.3 This standard does not purport to address all of the
powder can be calculated from these relative intensities using
safety concerns, if any, associated with its use. It is the
the Lambert-Beer law in the modified form (also see Refs 2, 3,
responsibility of the user of this standard to establish appro-
4).
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. DW 5 d ~logI 2 logI ! (1)
1–2 m d1 d2
where I and I are the intensities measured at the times
d1 d2
2. Referenced Documents
when all particles having diameters larger than d and d
1 2
2.1 ASTM Standards:
respectively have settled below the level of the light beam, d
m
B 330 Test Method for Fisher Number of Metal Powders
is the arithmetic mean of particle sizes d and d , and DW
1 2 1-2
and Related Compounds
refers to the relative weight for the particle size range between
B 821 Guide for Liquid Dispersion of Metal Powders and
d andd .Values of DW are determined for each of the particle
1 2
Related Compounds for Particle Size Analysis
size ranges chosen. The sum of these values is (DW. The
B 859 Practice for De-Agglomeration of Refractory Metal
weight percent of particles in the size range from d to d can
1 2
Powders and Their Compounds Prior to Particle Size
then be calculated as:
Analysis
Weight, % 5 ~DW /(DW! 3 100 (2)
4. Significance and Use
This test method is under the jurisdiction of ASTM Committee B09 on Metal
Powders and Metal Powder Products and is the direct responsibility of Subcom-
4.1 Knowledge of the particle size distribution of refractory
mittee B09.03 on Refractory Metal Powders.
metal powders is useful in predicting powder-processing be-
Current edition approved Sept. 10, 1997. Published February 1998. Originally
havior, and ultimate performance of powder metallurgy parts.
published as B 430 – 65 T. Last previous edition B 430 – 95.
The boldface numbers in parenthesis refer to the references listed at the end of
this test method.
Annual Book of ASTM Standards, Vol 02.05.
Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
B430
Particle size distribution is closely related to the flowability, 6.1.2.1 Daxad (No. 11) —Dissolve 25 mg in 1 L of base
compressibility, and die-filling characteristics of a powder, as medium.
wellastothefinalstructureandpropertiesofthefinishedparts. 6.1.2.2 Sodium Hexametaphosphate—Dissolve 0.1 g in 1 L
However, the degree of correlation between the results of this of base medium.
testmethodandthequalityofpowdersinusehasnotbeenfully
NOTE 2—Use water that is pure. Do not store the sedimentation
determined quantitatively.
medium longer than a week, and do not use rubber tubing in any storage
4.2 This test method is suitable for manufacturing control container. Clean thoroughly all sedimentation medium containers every
week.
and research and development in the production and use of
refractory metal-type powders, as indicated in 1.1.
7. Preparation of Apparatus
4.3 Reportedparticlesizemeasurementisafunctionofboth
7.1 Warm up equipment by turning on the light source and
the actual particle dimension and shape factor, as well as the
recorder for a minimum of 1 h prior to use.
particular physical or chemical properties being measured.
7.2 Fill the cell with sedimentation medium to a height
Caution is required when comparing data from instruments
sufficient to cover the light beam path by at least 10 mm and
operating on different physical or chemical parameters or with
place the cell in the turbidimeter (Note 3). If a microammeter
different particle size measurement ranges. Sample acquisition,
is used to measure light intensity, adjust the light transmission
handling, and preparation also can affect reported particle size
to 100 % using the diaphragm. If a millivolt recorder is used,
results.
adjust the potentiometer so that the photovoltaic cell output is
10 mV or 100 %. In this case, the diaphragm is not adjusted
5. Apparatus
and is completely open.
5.1 Turbidimeter(5)—Therecommendedinstrumentisone
NOTE 3—For convenience in filling the cell to the proper height,
using a cell rectangular in cross section, approximately 50 mm
inscribe a line on each face of the cell at the desired liquid-level height.
high, 40 mm wide, and 10-mm sedimentation medium thick-
The height of fall is usually 25 mm. To determine the location of the line,
ness, and having optically parallel faces.
the center of the light beam path must be established and 25 mm added to
5.2 Millivolt Recorder, 0 to 10-mV range, 10-in. (254-mm)
this value.
wide strip chart, 0 to 100 graduations, 120 in./h (50 mm/min)
7.3 After the instrument is adjusted to 100 % light transmis-
chart speed, or microammeter with 0 to 100 graduations,
sion through the sedimentation cell and medium, move the cell
15-µA full scale, 4.5-mV full scale.
carriage until light is passing through a reference glass held in
another slot of the cell carriage. Read and record the percent of
NOTE 1—While a 120-in./h (50-mm/min) chart speed is recommended,
reference light transmission. Having been selected to have
other speeds may be satisfactory.
approximately 70 to 95 % of the transmission of the sedimen-
5.3 Ultrasonic Cleaning Tank, with tank dimensions ap-
tation cell and medium, the reference glass will indicate 100 %
proximately 5 by 5 by 3 in. (127 by 127 by 76 mm) deep and
light transmission through the sedimentation cell when the
1 1 5
an output of 50 W, or approximately 3 ⁄2 by 3 ⁄2 by 2 ⁄8 in. (89
recorder reads this value through the reference cell.
by 89 by 67 mm) deep and an output of 25 W.
5.4 Glass Vial, nominal 2-dram, flat-bottom, with a tight-
8. Calculation of Times at Which Light Intensity is
fitting cap. The vial shall be approximately 2 in. (51 mm) in
Measured
height with a ⁄8-in. (16-mm) outside diameter and approxi-
8.1 The times at which the light transmission values should
mately a ⁄32-in. (0.8-mm) wall.
be read are calculated from Stokes’ law. A uniform 1-µm
interval should be used in making measurements through the
6. Reagents
10-µm size and, depending upon the particular powder, either
1-µm or 5-µm intervals thereafter. The form of Stokes’ law
6.1 Sedimentation Medium:
used is as follows:
6.1.1 Base Medium, distilled or deionized water (see Note
8 2
4).
t 5 ~18 3 10 Nh!/d ~r 2r !g (3)
x m
6.1.2 Use either one of the following as recommended in
where:
Guide B 821:
t = time, s,
N = viscosity of settling medium at ambient temperature,
P (Note 4),
h = height of fall, cm (distance from liquid level height
The recommended instrument is a Cenco Photelometer (not made anymore) of
original or modified designs or any proven equivalent instrument. A schematic
to midpoint of light beam),
diagram of the Photelometer is shown in the papers referenced at the end of this test
d = diameter of particle, µm (d , d , et al),
1 2
method. Copies of detailed drawings of an acceptable instrument are available from
r = theoretical density of the powder being tested (for
x
ASTM Headquarters. Order ADJA0430. A fabricated instrument can be secured
tungsten, use 19.3 g/cm ),
from WAB Instruments Co., 5171 Hickory Dr., Cleveland, OH 44124.
The 69800-Q1, Model S, Type G, Speedomax W, or XL630 Series recorder as
made by the Leeds and Northrup Co., have been found satisfactory.
Ultrasonic tank Model Nos. 2 or 12 as made by Bransonic Instrument Co.,
Stamford, CT, have been found satisfactory. Daxad No. 11 powder as made by the W. R. Grace and Co., Polymers and
Two-dram Titeseal vials, as made by Chemical Rubber Co., Cleveland, OH, Chemicals Div., 62 Whittemore Ave., Cambridge, MA 02140, has been found
have been found satisfactory. satisfactory.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
B430
a 5-min continuous hand-shake procedure. The 5-min ultra-
r = density of settling medium at ambient temperature
m
sonic treatment procedure is the preferred and recommended
(Note 4), and
procedure.
g = gravitational constant (980 cm/s ).
NOTE 6—The weight of the sample used should give a preferred initial
NOTE 4—The viscosity and density values at different temperatures that
lighttransmissionofbetween20and30 %.Transmissionsbetween15and
are used for the sedimentation medium in this procedure are the same as
40 %areacceptable.Ifitisdesiredtochangetheinitiallighttransmission,
for pure water. Some viscosity (from the Handbook of Chemistry and
reweigh another sample, increasing or decreasing the weight accordingly.
Physics, 65th Edition, CRC Press, 1984) and density (from Metrological
NOTE 7—Table 1 gives likely sample weight ranges for lab-milled
Handbook 145, NIST, 1990) values are given as follows:
tungsten powders having known Fisher sub-sieve sizer average particle
Temperature, Viscosity, Density,
diameters in the as-supplied condition. (See Test Method B 330.) These
°C °F cP g/cm
likely sample weight ranges apply for powders that have been lab-milled
18 64.4 1.0530 0.9986
before testing and either dispersed using the 5-min ultrasonic treatment or
19 66.2 1.0270 0.9984
the 5-min hand-shake procedure.The table also lists preferred micrometre
20 68.0 1.0020 0.9982
sizes to be read. For the determination of particle distribution of tungsten
21 69.8 0.9779 0.9980
in the as-supplied condition, or other powders, proper weights should be
22 71.6 0.9548 0.9978
determined by trial and error.
23 73.4 0.9325 0.9975
24 75.2 0.9111 0.9973
10.2 The 5-min ultrasonic treatment dispersion procedure is
25 77.0 0.8904 0.9970
as follows:
26 78.8 0.8705 0.9968
27 80.6 0.8513 0.9965
10.2.1 Fill the vial with 2 mL of sedimentation medium or
28 82.4 0.8327 0.9962
to a height of approximately ⁄4 in. (7.0 mm). Add weighed
29 84.2 0.8148 0.9959
amount of powder and cap the vial. Place into the ultrasonic
30 86.0 0.7975 0.9956
tank, handholding the vial for 5 min.
9. Conditioning (or De-agglomeration) of the Powder
NOTE 8—Depth of the liquid in the tank should be 1 ⁄2 to 2 in.
Prior to Analysis
(approximately 40 to 50 mm) from the bottom. Liquid in the tank is
distilled or deionized water, room temperature, with a small amount of
9.1 Foras-suppliedparticlesizedistributiondeterminations,
detergent. A 1-min warm-up of the ultrasonic tank is recommended prior
this step is not needed.
to vial immersion.
9.2 For laboratory-milled particle size distribution determi-
NOTE 9—If any of the powder sample is on the walls of the vial, the
nations, follow the procedure specified in Practice B 859.
liquid may be swirled before and during the ultrasonic treatment to rinse
thepowderdownintothebottom.Thevialneednotbeheldinastationary
NOTE 5—Since milled powder has a greater tendency than as-supplied
positionnorperpendiculartothebottom.Depthofimmersionandlocation
powder to pick up moisture and oxidize, the analysis procedure should be
of the vial are generally at the center portion of the tank, but may vary.
initiated immediately after milling is completed. This is particularly
Where cavitation within the vial is noticeable, as evidenced by rapid
important if the powder is to be dispersed using the 5-min hand-shake
agitation of the powder dispersion, the bottom of the vial could even be at
procedure (see Section 8) where a difference can be seen between
the surface of the tank liquid. Agitation within the vial should be
determinationsmadeinsuccessiononpowdershavingsignificantamounts
noticeable. Where agitation is not evident within the vial, the vial should
of 1-µm size powder. This difference, related to the size of the powder, is
be moved until agitation is evident. The vial generally is immersed to a
greater for fine powders. For all practical purposes, however, two runs can
depth where powder dispersion is at or below tank liquid level with the
be made in succession on each milled powder. If more than two runs on
vial bottom not closer than ⁄2 in. (about 10 mm) to the bottom of the tank.
the same milled powder are desired using the 5-min shake proced
...
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