1、Designation: D6059 96 (Reapproved 2011)Standard Test Method forDetermining Concentration of Airborne Single-CrystalCeramic Whiskers in the Workplace Environment byScanning Electron Microscopy1This standard is issued under the fixed designation D6059; the number immediately following the designation
2、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 () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the sampling m
3、ethods 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. This
4、testmethod is based on the collection of fibers by filtration of aknown quantity of air through a filter. The filter is subsequentlyevaluated with a scanning electron microscope (SEM) for thenumber of fibers meeting appropriately selected morphologicaland compositional criteria. This test method has
5、 the ability todistinguish among many different types of fibers based onenergy dispersive X-ray spectroscopy (EDS) analysis. This testmethod may be appropriate for other man-made mineral fibers(MMMF).1.2 This test method is applicable to the quantitation offibers on a collection filter that are grea
6、ter than 5 m in length,less than 3 m in width, and have an aspect ratio equal to orgreater than 5:1. The data are directly convertible to astatement of concentration per unit volume of air sampled. Thistest method is limited by the diameter of the fibers visible bySEM (typically greater than 0.10 to
7、 0.25 m in width asdetermined in 12.1.5) and the amount of coincident interfer-ence particles.1.3 A more definitive analysis may be necessary to confirmthe presence of fibers with diameters #0.10 to 0.25 m inwidth. For this purpose, a transmission electron microscope(TEM) is appropriate. The use of
8、the TEM method for theidentification and size measurement of SCCW is described inPractice D6058 and Test Method D6056.1.4 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.5 This standard does not purport to address all of thes
9、afety concerns, if any, associated with its use. It is theresponsibility of the user of this standard 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:2D1193 Specification for Reage
10、nt WaterD1356 Terminology Relating to Sampling and Analysis ofAtmospheresD4532 Test Method for Respirable Dust in WorkplaceAtmospheres Using Cyclone SamplersD6056 Test Method for Determining Concentration of Air-borne Single-Crystal Ceramic Whiskers in the WorkplaceEnvironment by Transmission Electr
11、on MicroscopyD6057 Test Method for Determining Concentration of Air-borne Single-Crystal Ceramic Whiskers in the WorkplaceEnvironment by Phase Contrast MicroscopyD6058 Practice for Determining Concentration of AirborneSingle-Crystal Ceramic Whiskers in the Workplace Envi-ronmentE691 Practice for Con
12、ducting an Interlaboratory Study toDetermine the Precision of a Test MethodE766 Practice for Calibrating the Magnification of a Scan-ning Electron Microscope3. Terminology3.1 Definitions:3.1.1 analytical sensitivity, nairborne fiber concentrationrepresented by a single fiber counted in the SEM.3.1.1
13、.1 DiscussionAlthough the terms fiber and whiskerare, for convenience, used interchangeably in this test method,whisker is correctly applied only to single-crystal fiberswhereas a “fiber” may be single- or poly-crystalline or may benoncrystalline.1This test method is under the jurisdiction of ASTM C
14、ommittee D22 on AirQuality and is the direct responsibility of Subcommittee D22.04 on Workplace AirQuality.Current edition approved Oct. 1, 2011. Published October 2011. Originallyapproved in 1996. Last previous edition approved in 2006 as D6059 - 96 (2006).DOI: 10.1520/D6059-96R11.2For referenced A
15、STM 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 Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Consho
16、hocken, PA 19428-2959, United States.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 length greater than 5 m, a widthless than 3 m, and an aspect ratio equal to or greater than 5:1.3.1.4 fibrous, adjc
17、omposed of parallel, radiating, or inter-laced aggregates of fibers, from which the fibers are sometimesseparable. That is, the aggregate may be referred to as fibrouseven if it is not composed of separable fibers, but has thatdistinct appearance. The term fibrous is used in a generalmineralogical w
18、ay to describe aggregates.3.1.5 man-made mineral fiber, nany inorganic fibrousmaterial produced by chemical or physical processes.3.1.6 single-crystal ceramic whiskers, n a man-mademineral fiber that has a single-crystal structure.3.2 For definitions of other terms used in this test method,see Termi
19、nology D1356.4. Summary of Test Method4.1 The sample is collected on a mixed cellulose ester(MCE) filter by drawing air, using a sampling pump, throughan open-face 25-mm electrically conductive sampling cassetteassembly (1,2).3A section of the filter is transferred to an SEMstub and the fibers are i
20、dentified, sized, and counted at amagnification of 20003 in the SEM using the criteria dis-cussed in Section 11. Results are expressed as a fiber concen-tration per unit volume of air and a fiber loading per unit areaof filter. The airborne concentration is expressed as fiber permillilitre (f/mL) an
21、d fiber loading is expressed as fibers persquare millimetre (f/mm2).5. Significance and Use5.1 The SCCW may be present in the workplace atmospherewhere these materials are manufactured, processed, trans-ported, or used. This test method can be used to monitorairborne concentrations of SCCW fibers in
22、 these environments.It may be employed as part of a personal or area monitoringstrategy.5.2 This test method is based on morphology and elementalcomposition. The analysis technique has the ability to identifySCCW.NOTE 1This test method assumes that the analyst is familiar with theoperation of SEM/ED
23、S instrumentation and the interpretation of dataobtained using these techniques.5.3 This test method is not appropriate for measurement offibers with diameters #0.10 to 0.25 m due to visibilitylimitations associated with SEM. The TEM method may beused to provide additional size information of SCCW i
24、f needed(see Practice D6058 for additional information on the use ofthis test method).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
25、and use it for reporting 95 %confidence limits (1,3,4).6. Interferences6.1 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 p
26、articles mayobscure the fibers by overlay or by overloading of the filter.This situation can be managed by regulating the air volumesampled and thus the filter loading. Fibers should appearseparated from other particles to ensure an adequate opportu-nity for their recognition as separate entities in
27、 the SEM andaccurate counting. Some coincident particle agglomerationdoes occur even with these guidelines. Analyze an alternatefilter with a reduced loading if the obscuring condition appearsto exceed 15 % of the filter area (5). Redeposition of a portionof an overloaded filter is permitted only in
28、 circumstanceswhere an alternate filter is not available and cannot be obtainedthrough resampling (see 10.1.5).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-
29、m pore-sizeMCE filter and a support pad. Seal the cassette assembly 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 andcontin
30、uously over the chosen sampling period (1). The flowmust be free from pulsation.All pumps shall be calibrated priorto use (6).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
31、L/min and continuously over the chosen sampling period(1). The flow shall be free from pulsation. All pumps shall becalibrated prior to use (6).7.4 Vinyl tubing or equivalent.7.5 Scanning Electron Microscope, a SEM capable of op-erating using an accelerating voltage of at least 15 kV. TheSEM must be
32、 capable of performing EDS analysis. A lightelement X-ray analyzer capable of detecting carbon, nitrogen,and oxygen is recommended.7.6 Vacuum EvaporatorFor vapor deposition of conduc-tive layers of carbon.NOTE 2Sputter coaters and carbonaceous fiber coaters are not appro-priate.7.7 SEM Sample Prepar
33、ation StubsStubs made of carbonare suitable. (A carbon planchet disk glued to a metal holder isalso acceptable.)7.8 Conducting DAG, (colloidal graphite) type adhesivepaint or double-sided conductive carbon tape.7.9 NIST SEM Magnification Standard, SRM 484 (see Prac-tice E766).7.10 Sample Preparation
34、 Area, consisting of either a cleanroom facility or a room containing a laminar flow hood.7.11 Specification D1193 Type II Water, (particle-free).7.12 Tweezers.7.13 Scalpel Blades.3The boldface numbers in parentheses refer to a list of references at the end ofthis test method.D6059 96 (2011)27.14 MC
35、E Filters, 25 mm, 0.45 and 0.22-m.7.15 Funnel/Filter Assembly, 25-mm.7.16 Miscellaneous Supplies.NOTE 3If the alternate sample preparation method discussed in 10.4is utilized, the following additional apparatus and reagents will benecessary:7.16.1 Oven, capable of operating at 65C is required tocoll
36、apse the filter. A hot plate capable of maintaining therequired temperature is an acceptable alternative to the oven.7.16.2 Plasma Asher, a low-temperature asher (LTA) isrequired to plasma-etch the collapsed MCE filter. A nominal100-W unit is suitable.7.16.3 Oxygen, used as a bleed gas in the plasma
37、 asher.7.16.4 Micro-syringe or Pipette, a device capable of consis-tently delivering a solution volume of 100 L is required.7.16.5 Dimethyl Formamide (DMF).7.16.6 Glacial Acetic Acid.7.16.7 Purity of ReagentsReagent grade chemicals shallbe used in all tests. Unless otherwise indicated, it is intende
38、dthat all reagents conform to the specifications of the Committeeon Analytical Reagents of the American Chemical Societywhere such specifications are available.4,5Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessen
39、ing theaccuracy of the determination.8. Sample Collection8.1 Collect samples of airborne SCCW on MCE filters usingsampling cassettes and pumps as noted in Section 7.8.2 Remove the outlet plug from the sampling cassette andconnect it to a sampling pump by means of flexible,constriction-proof tubing.8
40、.3 Perform a leak check of the sampling 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 toelimina
41、te any vacuum that may have accumulated 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 orient itface down. Adjust the calibrated fl
42、ow rate to a value between0.5 and 4 L/min (1). Typically, a sampling rate between 0.5 and2.5 L/min is selected (2-4,6,7). Also see Test Method D4532.8.5.2 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 (1). Typicall
43、y, a sampling rate between 1 and10 L/min is selected (8).8.5.3 Set the sampling flow rate and time to produce anoptimum fiber loading between 100 to 1300 f/mm2(1,2). Thetime of sampling can be estimated by using the followingequation:t 5Ac! FL!Q! Ce! 103(1)where:Ac= active filter collection area (;3
44、85 mm2for 25-mmfilter),5t = time, min,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 sa
45、mple shall be rejected. Also see Test MethodD4532.8.6 Carefully remove the cassette from the tubing at the endof the sampling period (ensure that the cassette is positionedupright before interrupting pump flow). Replace the inlet capand inlet and outlet plugs, and store the cassette.NOTE 4Deactivate
46、 the sampling pump prior to disconnecting 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 i
47、t. The fieldblank is used to monitor 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
48、 used in the laboratory. The sealed 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 vi
49、brations and cassette movement.NOTE 5Do not use shipping material that may develop electrostaticforces or generate dust.NOTE 6Shipping 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 information.10. Specimen Preparation10.1 The objective of the specimen preparation technique isto produce a sample suitable for analysis in the SEM. Proce-dures as described as follows or other equivalent methods maybe used to pr
