ASTM D6056-96(2001)

Standard Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environement by Transmission Electron Microscopy

SCOPE
1.1 This test method covers the sampling methods and analysis techniques used to assess the airborne concentration and size distribution of single-crystal ceramic whiskers (SCCW), such as silicon carbide and silicon nitride, which may occur in and around the workplace where these materials are manufactured, processed, transported, or used. This test method is based on the filtration of a known quantity of air through a filter. The filter is subsequently evaluated with a transmission electron microscope (TEM) for the number of fibers meeting appropriately selected morphological and compositional criteria. This test method has the ability to distinguish among different types of fibers based on energy dispersive X-ray spectroscopy (EDS) analysis and selected area electron diffraction (SAED) analysis. This test method may be appropriate for other man-made mineral fibers (MMMF).
1.2 This test method is applicable to the quantitation of fibers on a collection filter that are greater than 0.5 µm in length, less than 3 μm in width, and have an aspect ratio equal to or greater than 5:1 (1). The data are directly convertible to a statement of concentration per unit volume of air sampled. This test method is limited by the amount of coincident interference particles.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 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

• Status: Historical
• Publication Date: 09-Dec-1996
• ICS: 13.040.30 - Workplace atmospheres
• Technical Committee: D22 - Air Quality
• Drafting Committee: D22.04 - Workplace Air Quality

Relations

• Replaces: ASTM D6056-96 - Standard Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environement by Transmission Electron Microscopy
• Effective Date: 10-Dec-1996
• Replaced By: ASTM D6056-96(2006) - Standard Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Transmission Electron Microscopy
• Effective Date: 01-Oct-2006
• Referred By: ASTM D6058-96(2016) - Standard Practice for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment
• Effective Date: 10-Dec-1996

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:D6056–96 (Reapproved 2001)
Standard Test Method for
Determining Concentration of Airborne Single-Crystal
Ceramic Whiskers in the Workplace Environment by
Transmission Electron Microscopy
This standard is issued under the fixed designation D 6056; 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.
1. Scope 2. Referenced Documents
1.1 This test method covers the sampling methods and 2.1 ASTM Standards:
analysis techniques used to assess the airborne concentration D 1193 Specification for Reagent Water
and size distribution of single-crystal ceramic whiskers D 1356 Terminology Relating to Sampling and Analysis of
(SCCW),suchassiliconcarbideandsiliconnitride,whichmay Atmospheres
occur in and around the workplace where these materials are D 4532 Test Method for Respirable Dust in Workplace
manufactured, processed, transported, or used. This test Atmospheres
method is based on the filtration of a known quantity of air D 6057 Test Method for Determining Concentration of
through a filter. The filter is subsequently evaluated with a Airborne Single-Crystal Ceramic Whiskers in the Work-
transmission electron microscope (TEM) for the number of place Environment by Phase Contrast Microscopy
fibers meeting appropriately selected morphological and com- D 6058 Practice for Determining Concentration ofAirborne
positional criteria. This test method has the ability to distin- Single-Crystal Ceramic Whiskers in the Workplace Envi-
guish among different types of fibers based on energy disper- ronment
sive X-ray spectroscopy (EDS) analysis and selected area D 6059 Test Method for Determining Concentration of
electron diffraction (SAED) analysis. This test method may be Airborne Single-Crystal Ceramic Whiskers in the Work-
appropriate for other man-made mineral fibers (MMMF). place Environment by Scanning Electron Microscopy
1.2 This test method is applicable to the quantitation of E 691 Practice for Conducting Interlaboratory Study to
fibers on a collection filter that are greater than 0.5 µm in Determine the Precision of a Test Method
length, less than 3 µm in width, and have an aspect ratio equal
2 3. Terminology
to or greater than 5:1 (1). The data are directly convertible to
a statement of concentration per unit volume of air sampled. 3.1 Definitions:
3.1.1 analytical sensitivity, n—airborne fiber concentration
This test method is limited by the amount of coincident
interference particles. represented by a single fiber counted in the TEM.
3.1.1.1 Discussion—Although the terms fiber and whisker
1.3 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are for information are, for convenience, used interchangeably in this test method,
whiskers is correctly applied only to single-crystal fibers
only.
1.4 This standard does not purport to address all of the whereas a fiber may be single- or poly-crystalline or may be
noncrystalline.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 3.1.2 aspect ratio, n—the ratio of the length of a fiber to its
width.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. 3.1.3 fiber, n—for the purpose of this test method,an
elongated particle having a minimum length of 0.5 µm, a width
less than 3 µm, and an aspect ratio equal to or greater than 5:1.
This test method is under the jurisdiction of ASTM Committee D22 on
Sampling andAnalysis and is the direct responsibility of Subcommittee D22.04 on
Workplace Atmospheres. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Dec. 10, 1996. Published February 1997. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
The boldface numbers in parentheses refer to a list of references at the end of Standards volume information, refer to the standard’s Document Summary page on
this test method. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6056–96 (2001)
3.1.4 fibrous, adj—composed of parallel, radiating, or inter- other particles to ensure an adequate opportunity for their
laced aggregates of fibers, from which the fibers are sometimes recognition as separate entities in the TEM and accurate
separable. That is, the crystalline aggregate may be referred to counting. Some coincident particulate agglomeration does
asfibrousevenifitisnotcomposedofseparablefibers,buthas occur even with these guidelines. Analyze an alternate filter
that distinct appearance. The term fibrous is used in a general with a reduced loading if the obscuring condition appears to
mineralogical way to describe aggregates. exceed 15 % of the filter area (7). Redeposition of a portion of
3.1.5 man-made mineral fiber, n—any inorganic fibrous an overloaded filter is permitted only in circumstances where
material produced by chemical or physical processes. an alternate filter is not available and cannot be obtained
3.1.6 single-crystal ceramic whisker, n— a man-made min- through resampling (see 10.1.12).
eral fiber that has a single-crystal structure.
3.2 For definitions of other terms used in this test method, 7. Apparatus and Reagents
see Terminology D 1356.
7.1 Sampling Cassette—Use a 25-mm electrically conduc-
tive cassette assembly such as a three-piece cassette with an
4. Summary of Test Method
extension cowl or retainer ring containing a 0.45-µm pore size
4.1 The sample is collected on a mixed cellulose ester
MCE filter and a support pad. Seal the cassette assembly with
(MCE) filter by drawing air, using a sampling pump, through
shrink tape. Reloading of used cassettes is not permitted.
an open-face 25-mm electrically conductive sampling cassette
7.2 Personal Sampling Pump—Use a portable battery-
assembly (2-4). A section of the filter is prepared and trans-
operated pump for personal sampling. Each pump must be
ferred to a TEM grid and the fibers are identified, sized, and
capable of operating within the range from 0.5 to 4 L/min and
counted at a screen magnification in the range from 8000 to
continuously over the chosen sampling period (2,3). The flow
12 0003 in the TEM in Section 11. Results are reported as a
mustbefreefrompulsation.Allpumpsshallbecalibratedprior
fiber concentration per unit volume of air and a fiber loading
to use (8).
per unit area of filter. The airborne concentration is expressed
7.3 Area Sampling Pump—Use a personal sampling pump
as fibers per millilitre (f/mL) and the fiber loading is expressed
or a non-portable high-volume pump for area sampling. Each
as fibers per square millimetre (f/mm ). Optionally, a supple-
pump shall be capable of operating within the range from 0.5
mentary low-magnification count in the range from 800 to
to 16 L/min and continuously over the chosen sampling period
12003 may also be performed, using the criteria discussed in
(2,3).The flow shall be free from pulsation.All pumps shall be
11.1.5, to provide comparison with PCM data.
calibrated prior to use (8).
7.4 Vinyl tubing or equivalent.
5. Significance and Use
7.5 Plasma Asher, a low-temperature asher (LTA) is re-
5.1 TheSCCWmaybepresentintheworkplaceatmosphere quired to plasma-etch the collapsed MCE filter.
where these materials are manufactured, processed, trans- 7.6 Oxygen, used as a bleed gas for plasma asher.
ported, or used. This test method can be used to monitor 7.7 Vacuum Evaporator, for vapor deposition of conductive
airborne concentrations of fibers in these environments. It may layers of carbon.
be employed as part of a personal or area monitoring strategy.
NOTE 2—Sputter coaters and carbonaceous fiber coaters are not appro-
5.2 This test method is based on morphology, elemental
priate.
composition, and crystal structure. The analysis technique has
7.8 Specimen Grids, copper 200-mesh TEM grids for
the ability to positively identify SCCW.
mounting the specimen for TEM examination.
NOTE 1—This test method assumes that the analyst is familiar with the
7.9 Transmission Electron Microscope—ATEM capable of
operation of TEM/EDS instrumentation and the interpretation of data
operating using an accelerating voltage of at least 80 kV. The
obtained using these techniques.
TEM must also be capable of performing EDS and SAED
5.3 This test method is applicable for the measurement of
analyses. A light-element X-ray analyzer capable of detecting
the total population of SCCW fibers including fibers with
carbon, nitrogen, and oxygen is recommended. Use of a
diameters#0.1 µm.
tilt-rotation holder as well as a double-tilt stage is also
5.4 Resultsfromtheuseofthistestmethodshallbereported
recommended. The TEM must have a fluorescent screen
along with 95 % confidence limits for the samples being
inscribed with calibrated gradations. It must be capable of
studied. Individual laboratories shall determine their intralabo-
producing a spot less than 250 nm in diameter at crossover
ratory coefficient of variation and use it for reporting 95 %
under routine analytical conditions. Scanning transmission
confidence limits (2,5,6).
electron microscope (STEM) mode is allowed for this purpose.
7.10 Sample Preparation Area, consisting of either a clean
6. Interferences
room facility or a room containing a positive pressure HEPA-
6.1 This test method has been designed to filter air for the filtered hood.
determination of SCCW concentration. However, filtration of 7.11 Tweezers.
air also involves collection of extraneous particles and other 7.12 Scalpel Blades.
fibers that may not be of interest. Extraneous particles may 7.13 Large Glass Petri Dishes (approximately 90 mm in
obscure fibers by overlay or overloading of the filter. This diameter).
situationcanbemanagedbyregulatingtheairvolumesampled 7.14 Jaffe Washer.
and thusthefilterloading.Fibersshouldappearseparatedfrom 7.15 Lens Tissue.
D6056–96 (2001)
7.16 MCE Filters, 25 mm, 0.45 µm, and 0.22 µm.
Q = sampling flow rate, L/min,
7.17 Funnel/Filtration Assembly,25mm.
C = estimated concentration of SCCW, f/mL, and
e
7.18 Acetone.
10 = conversion factor.
8.5.4 At a minimum, check the flow rate before and after
NOTE 3—Precaution: Acetone is a flammable liquid and requires
sampling. If the difference is greater than 10 % from the initial
precautions not to ignite it accidently.
flow rate, the sample shall be rejected. Also see Test Method
7.19 Specification D 1193 Type II Water (particle free).
D 4532.
7.20 Purity of Reagents—Reagent grade chemicals shall be
8.6 Carefully remove the cassette from the tubing at the end
used in all tests. Unless otherwise indicated, it is intended that
of the sampling period (ensure that the cassette is positioned
all reagents conform to the specifications of the Committee on
upright before interrupting the pump flow). Replace the inlet
Analytical Reagents of the American Chemical Society where
cap and inlet and outlet plugs, and store the cassette.
such specifications are available. Other grades may be used,
NOTE 4—Deactivate the sampling pump prior to disconnecting the
provided it is first ascertained that the reagent is of sufficiently
cassette from the tubing.
high purity to permit its use without lessening the accuracy of
the determination.
8.7 Submit at least one field blank (or a number equal to
10 % of the total samples, whichever is greater) for each set of
8. Sample Collection
samples. Remove the cap of the field blank briefly (approxi-
8.1 CollectsamplesofairborneSCCWonMCEfiltersusing mately 30 s) at the sampling site, then replace it. The field
sampling cassettes and pumps in accordance with Section 7. blank is used to monitor field sampling procedures. Field
8.2 Remove the outlet plug from the sampling cassette and
blanks shall be representative of filters used in sample collec-
connect to a sampling pump by means of flexible, constriction tion (for example, same filter lot number).
proof tubing.
8.8 Submit at least one unused and unopened sealed blank
8.3 Perform a leak check of the sampling system by which is used to monitor the supplies purchased as well as
activating the pump with the closed cassette and rotameter (or
procedures used in the laboratory. The sealed blank shall be
other flow measurement device) in line. Any flow indicates a representative of filters used in sample collection (for example,
leak that must be eliminated before starting the sampling same filter lot number).
operation.
9. Transport of Samples
8.4 Remove the inlet plug from the sampling cassette to
eliminate any vacuum that may have accumulated during the 9.1 Ship the samples in a rigid container with sufficient
leak test; then remove the entire inlet cap.
packing material to prevent jostling or damage. Care shall be
8.5 Conduct personal and area sampling as follows: taken to minimize vibrations and cassette movement.
8.5.1 For personal sampling, fasten the sampling cassette to
NOTE 5—Do not use shipping material that may develop electrostatic
the worker’s lapel in the worker’s breathing zone and orient
forces or generate dust.
face down. Adjust the calibrated flow rate to a value between
NOTE 6—Shipping containers for 25-mm sampling cassettes are com-
0.5 and 4 L/min (2,3). Typically, a sampling rate between 0.5
mercially available and their use is recommended.
and 2.5 L/min is selected (4-7).Also see Test Method D 4532.
9.2 Include in the container a list of samples, their descrip-
8.5.2 Placeareasamplesonanextensionrodfacingdownat
tions, and all other pertinent information.
a 45° angle.Adjust the calibrated flow rate to a value between
0.5 and 16 L/min (2,3). Typically, a sampling rate between 1
10. Specimen Preparation
and 10 L/min is selected (1).
10.1 The objective of the specimen preparation technique is
8.5.3 Set the sampling flow rate and time to produce an
to produce a thin carbon film (sufficiently clear for the TEM
optimum fiber loading between 100 and 1300 f/mm (2-4) .
analysis) containing the particles from the filter surface. This
The time of sampling can be estimated by using the following
requires four separate preparation steps: (1) partially fuse or
equation:
collapse the filter to obtain a more continuous surface for the
~A ! ~F !
evaporated carbon layer, (2) in a low temperature asher, lightly
c L
t 5 (1)
~Q! ~C !10
etch the filter surface to uncover any fibers that may have been
e
covered in the collapsing step, (3) evaporate a thin carbon film
where:
over the collapsed and etched filter, and (4) dissolve the MCE
A = active filter c
...