1、Designation: D 6056 96 (Reapproved 2006)Standard Test Method forDetermining Concentration of Airborne Single-CrystalCeramic Whiskers in the Workplace Environment byTransmission Electron Microscopy1This standard is issued under the fixed designation D 6056; the number immediately following the design
2、ation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the sam
3、pling methods andanalysis techniques used to assess the airborne concentrationand size distribution of single-crystal ceramic whiskers(SCCW), such as silicon carbide and silicon nitride, which mayoccur in and around the workplace where these materials aremanufactured, processed, transported, or used
4、. This testmethod is based on the filtration of a known quantity of airthrough a filter. The filter is subsequently evaluated with atransmission electron microscope (TEM) for the number offibers meeting appropriately selected morphological and com-positional criteria. This test method has the abilit
5、y to distin-guish among different types of fibers based on energy disper-sive X-ray spectroscopy (EDS) analysis and selected areaelectron diffraction (SAED) analysis. This test method may beappropriate for other man-made mineral fibers (MMMF).1.2 This test method is applicable to the quantitation of
6、fibers on a collection filter that are greater than 0.5 m inlength, less than 3 m in width, and have an aspect ratio equalto or greater than 5:1 (1).2The data are directly convertible toa statement of concentration per unit volume of air sampled.This test method is limited by the amount of coinciden
7、tinterference particles.1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this s
8、tandard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3D 1193 Specification for Reagent WaterD 1356 Terminology Relating to Sampling and Analysis ofAtmospheresD 4532 Test Method
9、for Respirable Dust in WorkplaceAtmospheresD 6057 Test Method for Determining Concentration ofAirborne Single-Crystal Ceramic Whiskers in the Work-place Environment by Phase Contrast MicroscopyD 6058 Practice for Determining Concentration ofAirborneSingle-Crystal Ceramic Whiskers in the Workplace En
10、vi-ronmentD 6059 Test Method for Determining Concentration ofAirborne Single-Crystal Ceramic Whiskers in the Work-place Environment by Scanning Electron MicroscopyE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions:3.1.1 anal
11、ytical sensitivity, nairborne fiber concentrationrepresented by a single fiber counted in the TEM.3.1.1.1 DiscussionAlthough the terms fiber and whiskerare, for convenience, used interchangeably in this test method,whiskers is correctly applied only to single-crystal fiberswhereas a fiber may be sin
12、gle- or poly-crystalline or may benoncrystalline.3.1.2 aspect ratio, nthe ratio of the length of a fiber to itswidth.3.1.3 fiber, nfor the purpose of this test method,anelongated particle having a minimum length of 0.5 m, a widthless than 3 m, and an aspect ratio equal to or greater than 5:1.1This t
13、est method is under the jurisdiction of ASTM Committee D22 on AirQuality and is the direct responsibility of Subcommittee D22.04 on WorkplaceAtmospheres.Current edition approved Oct. 1, 2006. Published October 2006. Originallyapproved in 1996. Last previous edition approved in 2001 as D 6056 - 96 (2
14、001).2The boldface numbers in parentheses refer to a list of references at the end ofthis test method.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards
15、Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.4 fibrous, adjcomposed of parallel, radiating, or inter-laced aggregates of fibers, from which the fibers are sometimesseparable. That is, t
16、he crystalline aggregate may be referred toas fibrous even if it is not composed of separable fibers, but hasthat distinct appearance. The term fibrous is used in a generalmineralogical way to describe aggregates.3.1.5 man-made mineral fiber, nany inorganic fibrousmaterial produced by chemical or ph
17、ysical processes.3.1.6 single-crystal ceramic whisker, n a man-made min-eral fiber that has a single-crystal structure.3.2 For definitions of other terms used in this test method,see Terminology D 1356.4. Summary of Test Method4.1 The sample is collected on a mixed cellulose ester(MCE) filter by dra
18、wing air, using a sampling pump, throughan open-face 25-mm electrically conductive sampling cassetteassembly (2-4). A section of the filter is prepared and trans-ferred to a TEM grid and the fibers are identified, sized, andcounted at a screen magnification in the range from 8000 to12 0003 in the TE
19、M in Section 11. Results are reported as afiber concentration per unit volume of air and a fiber loadingper unit area of filter. The airborne concentration is expressedas fibers per millilitre (f/mL) and the fiber loading is expressedas fibers per square millimetre (f/mm2). Optionally, a supple-ment
20、ary low-magnification count in the range from 800 to12003 may also be performed, using the criteria discussed in11.1.5, to provide comparison with PCM data.5. Significance and Use5.1 The SCCW may be present in the workplace atmospherewhere these materials are manufactured, processed, trans-ported, o
21、r used. This test method can be used to monitorairborne concentrations of fibers in these environments. It maybe employed as part of a personal or area monitoring strategy.5.2 This test method is based on morphology, elementalcomposition, and crystal structure. The analysis technique hasthe ability
22、to positively identify SCCW.NOTE 1This test method assumes that the analyst is familiar with theoperation of TEM/EDS instrumentation and the interpretation of dataobtained using these techniques.5.3 This test method is applicable for the measurement ofthe total population of SCCW fibers including fi
23、bers withdiameters #0.1 m.5.4 Results from the use of this test method shall be reportedalong with 95 % confidence limits for the samples beingstudied. Individual laboratories shall determine their intralabo-ratory coefficient of variation and use it for reporting 95 %confidence limits (2,5,6).6. In
24、terferences6.1 This test method has been designed to filter air for thedetermination of SCCW concentration. However, filtration ofair also involves collection of extraneous particles and otherfibers that may not be of interest. Extraneous particles mayobscure fibers by overlay or overloading of the
25、filter. Thissituation can be managed by regulating the air volume sampledand thus the filter loading. Fibers should appear separated fromother particles to ensure an adequate opportunity for theirrecognition as separate entities in the TEM and accuratecounting. Some coincident particulate agglomerat
26、ion doesoccur even with these guidelines. Analyze an alternate filterwith a reduced loading if the obscuring condition appears toexceed 15 % of the filter area (7). Redeposition of a portion ofan overloaded filter is permitted only in circumstances wherean alternate filter is not available and canno
27、t be obtainedthrough resampling (see 10.1.12).7. Apparatus and Reagents7.1 Sampling CassetteUse a 25-mm electrically conduc-tive cassette assembly such as a three-piece cassette with anextension cowl or retainer ring containing a 0.45-m pore sizeMCE filter and a support pad. Seal the cassette assemb
28、ly withshrink tape. Reloading of used cassettes is not permitted.7.2 Personal Sampling PumpUse a portable battery-operated pump for personal sampling. Each pump must becapable of operating within the range from 0.5 to 4 L/min andcontinuously over the chosen sampling period (2,3). The flowmust be fre
29、e from pulsation.All pumps shall be calibrated priorto use (8).7.3 Area Sampling PumpUse a personal sampling pumpor a non-portable high-volume pump for area sampling. Eachpump shall be capable of operating within the range from 0.5to 16 L/min and continuously over the chosen sampling period(2,3). Th
30、e flow shall be free from pulsation. All pumps shall becalibrated prior to use (8).7.4 Vinyl tubing or equivalent.7.5 Plasma Asher, a low-temperature asher (LTA) is re-quired to plasma-etch the collapsed MCE filter.7.6 Oxygen, used as a bleed gas for plasma asher.7.7 Vacuum Evaporator, for vapor dep
31、osition of conductivelayers of carbon.NOTE 2Sputter coaters and carbonaceous fiber coaters are not appro-priate.7.8 Specimen Grids, copper 200-mesh TEM grids formounting the specimen for TEM examination.7.9 Transmission Electron MicroscopeATEM capable ofoperating using an accelerating voltage of at
32、least 80 kV. TheTEM must also be capable of performing EDS and SAEDanalyses. A light-element X-ray analyzer capable of detectingcarbon, nitrogen, and oxygen is recommended. Use of atilt-rotation holder as well as a double-tilt stage is alsorecommended. The TEM must have a fluorescent screeninscribed
33、 with calibrated gradations. It must be capable ofproducing a spot less than 250 nm in diameter at crossoverunder routine analytical conditions. Scanning transmissionelectron microscope (STEM) mode is allowed for this purpose.7.10 Sample Preparation Area, consisting of either a cleanroom facility or
34、 a room containing a positive pressure HEPA-filtered hood.7.11 Tweezers.7.12 Scalpel Blades.7.13 Large Glass Petri Dishes (approximately 90 mm indiameter).7.14 Jaffe Washer.7.15 Lens Tissue.D 6056 96 (2006)27.16 MCE Filters, 25 mm, 0.45 m, and 0.22 m.7.17 Funnel/Filtration Assembly,25mm.7.18 Acetone
35、.(WarningAcetone is a flammable liquidand requires precautions not to ignite it accidently.)7.19 Specification D 1193 Type II Water (particle free).7.20 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the spe
36、cifications of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are available.4Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.8.
37、 Sample Collection8.1 Collect samples of airborne SCCW on MCE filters usingsampling cassettes and pumps in accordance with Section 7.8.2 Remove the outlet plug from the sampling cassette andconnect to a sampling pump by means of flexible, constrictionproof tubing.8.3 Perform a leak check of the samp
38、ling system byactivating the pump with the closed cassette and rotameter (orother flow measurement device) in line. Any flow indicates aleak that must be eliminated before starting the samplingoperation.8.4 Remove the inlet plug from the sampling cassette toeliminate any vacuum that may have accumul
39、ated during theleak test; then remove the entire inlet cap.8.5 Conduct personal and area sampling as follows:8.5.1 For personal sampling, fasten the sampling cassette tothe workers lapel in the workers breathing zone and orientface down. Adjust the calibrated flow rate to a value between0.5 and 4 L/
40、min (2,3). Typically, a sampling rate between 0.5and 2.5 L/min is selected (4-7). Also see Test Method D 4532.8.5.2 Place area samples on an extension rod facing down ata 45 angle. Adjust the calibrated flow rate to a value between0.5 and 16 L/min (2,3). Typically, a sampling rate between 1and 10 L/
41、min is selected (1).8.5.3 Set the sampling flow rate and time to produce anoptimum fiber loading between 100 and 1300 f/mm2(2-4) .The time of sampling can be estimated by using the followingequation:t 5Ac! FL!Q! Ce! 103(1)where:Ac= active filter collection area (;385 mm2for 25-mmfilter),5t = time, m
42、in,FL= fiber loading, f/mm2,Q = sampling flow rate, L/min,Ce= estimated concentration of SCCW, f/mL, and103= conversion factor.8.5.4 At a minimum, check the flow rate before and aftersampling. If the difference is greater than 10 % from the initialflow rate, the sample shall be rejected. Also see Te
43、st MethodD 4532.8.6 Carefully remove the cassette from the tubing at the endof the sampling period (ensure that the cassette is positionedupright before interrupting the pump flow). Replace the inletcap and inlet and outlet plugs, and store the cassette.NOTE 3Deactivate the sampling pump prior to di
44、sconnecting thecassette from the tubing.8.7 Submit at least one field blank (or a number equal to10 % of the total samples, whichever is greater) for each set ofsamples. Remove the cap of the field blank briefly (approxi-mately 30 s) at the sampling site, then replace it. The fieldblank is used to m
45、onitor field sampling procedures. Fieldblanks shall be representative of filters used in sample collec-tion (for example, same filter lot number).8.8 Submit at least one unused and unopened sealed blankwhich is used to monitor the supplies purchased as well asprocedures used in the laboratory. The s
46、ealed blank shall berepresentative of filters used in sample collection (for example,same filter lot number).9. Transport of Samples9.1 Ship the samples in a rigid container with sufficientpacking material to prevent jostling or damage. Care shall betaken to minimize vibrations and cassette movement
47、.NOTE 4Do not use shipping material that may develop electrostaticforces or generate dust.NOTE 5Shipping containers for 25-mm sampling cassettes are com-mercially available and their use is recommended.9.2 Include in the container a list of samples, their descrip-tions, and all other pertinent infor
48、mation.10. Specimen Preparation10.1 The objective of the specimen preparation technique isto produce a thin carbon film (sufficiently clear for the TEManalysis) containing the particles from the filter surface. Thisrequires four separate preparation steps: (1) partially fuse orcollapse the filter to
49、 obtain a more continuous surface for theevaporated carbon layer, (2) in a low temperature asher, lightlyetch the filter surface to uncover any fibers that may have beencovered in the collapsing step, (3) evaporate a thin carbon filmover the collapsed and etched filter, and (4) dissolve the MCEfilter and retain the carbon film with particles for TEManalysis. Procedures described as follows or other equivalentmethods (for example, dimethyl formamide (DMF) procedure(9) may be used to prepare samples.10.1.1 Wipe the exterior of the cassettes with a damp c
