1、Designation: D1082 17Standard Test Method forDissipation Factor and Permittivity (Dielectric Constant) ofMica1This standard is issued under the fixed designation D1082; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of the dissi-pation factor and the relative permittivity of natural block mic
3、ahaving thicknesses between 0.007 and 0.030 in. (0.18 and0.77 mm) and mica films or capacitor splits between 0.0008and 0.004 in. (0.02 and 0.10 mm) in thickness.1.2 The values stated in inch-pound units are to be regardedas the standard. The values in parentheses are for informationpurposes only.1.3
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 standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use. A
5、specific warning statement is given in Section 7 and 6.1.1.NOTE 1Procedures for the measurement of dissipation factor andpermittivity are given in IEC Publication 60371-2, but the details of theprocedure are somewhat different from those specified in this test method.1.4 This international standard
6、was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Refere
7、nced Documents2.1 ASTM Standards:2D150 Test Methods for AC Loss Characteristics and Permit-tivity (Dielectric Constant) of Solid Electrical InsulationD374 Test Methods for Thickness of Solid Electrical Insu-lation (Metric) D0374_D0374MD748 Specification for Natural Block Mica and Mica FilmsSuitable
8、for Use in Fixed Mica-Dielectric Capacitors2.2 IEC Publication:Publication 60371-2 Specification for insulating materialsbased on micaPart 2: Methods of test33. Summary of Test Method3.1 Any of the techniques and apparatus set forth in TestMethods D150 are suitable for measuring dissipation factoran
9、d relative permittivity of block mica or film. Select anappropriate electrode system from those given in Section 5.3.2 If a relative order of magnitude of dissipation factor isdesired, the use of Method A in the Appendix of SpecificationD748 is satisfactory.4. Significance and Use4.1 The dissipation
10、 factor of natural muscovite mica, asdetermined by this test method, is of practical importance as ameasure of the electrical energy lost as heat in the mica servingas the dielectric substance of capacitors, or in other applica-tions in which the electric field is applied perpendicular to theplane o
11、f cleavage. The dissipation factor is particularly impor-tant in applications using mica at radio frequencies and in someless extensive audio frequency applications. This test method issuitable for specification acceptance and dielectric-loss controltests (see the Significance and Use of Test Method
12、s D150).4.2 Relative Permittivity (Dielectric Constant)The per-mittivity of natural muscovite mica is a measure of its relativeability to store electrostatic energy. Since the relative permit-tivity perpendicular to the cleavage plane is fairly uniform,regardless of origin, its practical significanc
13、e is mainly foridentification purposes, special uses, research, and design. If aloss index is desired, the value of the permittivity must beknown (see the Significance and Use of Test Methods D150).5. Apparatus5.1 For a general description of apparatus suitable formeasuring dissipation factor and re
14、lative permittivity, refer toTest Methods D150.1This test method is under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materialsand is the direct responsibility ofSubcommittee D09.01 on Electrical Insulating Products.Current edition approved Nov. 1, 2017. Published D
15、ecember 2017. Originallyapproved in 1949. Last previous edition approved in 2011 as D1082 00 (2011).DOI: 10.1520/D1082-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, ref
16、er to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, W
17、est Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World
18、Trade Organization Technical Barriers to Trade (TBT) Committee.15.2 Select a suitable electrode arrangement from the follow-ing:5.2.1 Steel ElectrodesThree electrodes made of stainlesssteel or nickel-plated tool steel will be required. The electrodesshall be cylindrical in shape and of a diameter su
19、fficient toprovide the minimum specified capacitance (Note 2). Theupper and lower electrodes shall have a minimum axial lengthof12 in. (12.7 mm) and the center electrode shall have amaximum length of14 in. (6.35 mm). A low-resistance contactand conductor to the electrode is essential for dissipation
20、 factormeasurements in the order of 0.0001. The upper and lowerelectrodes shall be electrically connected together, thus form-ing a two-terminal capacitor, with the center electrode servingas the active or measuring terminal. The surfaces of theelectrodes adjacent to the specimen shall be ground and
21、polished optically flat, and shall be parallel to each other. Theupper electrode shall be provided with a recess for a steel ball,so that the applied pressure will be uniformly distributed. Theelectrodes shall be carefully and accurately aligned withoutscratching the surface of the mica specimen. It
22、 is recommendedthat a slotted V-shaped jig be provided to aid with the aligningof the electrodes.NOTE 2Steel electrodes having diameters of34 ,1,114, and 112 in.(19, 25, 32, and 38 mm) have been found satisfactory for practicalthicknesses of mica specimens.5.2.2 Mercury ElectrodesThree hollow, stain
23、less steel ornickel-plated cold-rolled steel electrodes mounted with the axishorizontal so that the test specimens are in a vertical plane, willbe required as shown in Fig. 1. The electrode assembly shall becylindrical in shape and of the same outside diameter, whichshall be large enough to provide
24、the minimum specifiedcapacitance (Note 3). Two adjustable electrodes having axiallengths of approximately34 in. (19 mm), provided withsuitable cavities, shall be mounted on screws in a solidstainless steel or nickel-plated cold-rolled steel rectangularyoke. A center, or fixed, electrode consisting o
25、f a hollow ringapproximately38 in. (9.5 mm) in length shall be mounted at thecenter of the steel yoke on a support of insulating material suchas polystyrene, hard rubber, low-loss ceramic, or quartz. Allelectrodes shall taper from the inside to rather sharp edgesapproximately164 in. (0.4 mm) in widt
26、h.5.2.2.1 The two outer electrodes shall be provided with arubber tube attached to18-in. (3.2-mm) steel tubes located atthe bottom of each electrode. Small vent holes shall beprovided in the top of the outer electrodes to permit the escapeof entrapped air as the mercury rises. The center electrode s
27、hallbe filled through a18-in. steel tube projecting approximately18in. above the top of the electrode and extending three fourths ofthe way down inside the steel ring. Vent holes shall be providedon either side of the projecting steel tube to permit entrappedair to escape as the mercury rises. With
28、the test specimensclamped in position, the electrodes shall be in good alignment.As in the case of the flat, steel electrodes, a two-terminalcapacitor is formed with the center electrode serving as theactive or measuring terminal with the outer electrodes that areconnected together by the steel yoke
29、 at the ground.NOTE 3Mercury electrodes having diameters of 134 in. (44.5 mm)have been found satisfactory for mica specimens 2 by 2 in. by 0.001 to0.030 in. (51 by 51 mm by 0.025 to 0.76 mm).NOTE 4Conducting paint electrodes can be substituted for mercuryelectrodes.5.2.3 Lead-Foil ElectrodesThe use
30、of lead-foil electrodes0.0005 in. (0.013 mm) in thickness and 2.0 in. (51 mm) indiameter is satisfactory for block mica 0.015 to 0.030 in. (0.38to 0.76 mm) in thickness. (See also metal-foil electrodesdescribed in the Section of Test Methods D150 under ElectrodeSystems).5.3 The apparatus for the rap
31、id, direct-reading method is setforth in Appendix of Specification D748. This technique is foruse only where classification of relative magnitude of dissipa-tion factor (or its reciprocal Q value) of block mica or films isdesired.5.4 Thickness-measuring apparatus shall conform to therequirements set
32、 forth in Test Method A of Test Methods D374which describes a machinists micrometer caliper with aratchet or friction thimble.6. Specimen Preparation and Conditioning6.1 The dielectric properties of mica are affected bytemperature, humidity, pressure, etc. Therefore, preparationand conditioning of t
33、he specimen shall be made in thefollowing manner:6.1.1 With the exception of the specimens used in 5.4,thoroughly and carefully clean the surfaces of the specimenwith a camels-hair brush dipped in petroleum ether or vapordegrease using trichloroethylene. Subsequent to the cleaning,exercise care not
34、to contaminate the surfaces in handling.(WarningPetroleum ether and trichlorethylene are hazard-ous. Use adequately ventilated work areas and observe allprocedures for the safe handling of these liquids. Keep awayfrom open flames.)6.1.2 After cleaning, place each specimen in an air ovenmaintained at
35、 105 to 110C, for a period of 1 h. Upon removalfrom the oven, immediately store the specimen in a desiccatoruntil ready for the test.6.2 Prepare two similar test specimens of approximatelyequal and uniform thickness for each measurement when usingsteel or mercury electrodes (see Section 5).FIG. 1 Me
36、rcury Electrode Test AssemblyD1082 1726.3 Only one test specimen is needed for testing withlead-foil electrodes.6.4 Obtain specimens from the same block or splitting whentwo specimens are used. Each specimen shall have a sufficientarea and thickness to give a total capacitance of not less than200 pF
37、. Test a sufficient number of specimens to obtainrepresentative data.7. Procedure7.1 When steel, mercury, or lead-foil electrodes are used,determine the dissipation factor and relative permittivity of themica in accordance with Test Methods D150 except for sizeand type of electrode.7.2 WarningMercur
38、y metal vapor poisoning has longbeen recognized as a hazard in industry. The exposure limitsare set by governmental agencies and are usually based uponrecommendations made by the American Conference of Gov-ernmental Industrial Hygienists.4The concentration of mer-cury vapor over spills from broken t
39、hermometers, barometers,and other instruments using mercury can easily exceed theseexposure limits. Mercury, being a liquid with high surfacetension and quite heavy, will disperse into small droplets andseep into cracks and crevices in the floor. This increased areaof exposure adds significantly to
40、the mercury vapor concen-tration in air. The use of a commercially available emergencyspill kit is recommended whenever a spill occurs. Mercuryvapor concentration is easily monitored using commerciallyavailable sniffers. Make spot checks periodically around op-erations where mercury is exposed to th
41、e atmosphere. Makethorough checks after spills.7.3 Certain types of micas are affected by pressure;therefore, when flat, steel electrodes are used, apply a sufficientrange of pressures (Note 5) so that plotting curves of pressurein pounds-force per square inch versus dissipation factor andrelative p
42、ermittivity is possible.NOTE 5Pressures in the order of 100 to 10 000 psi are readily obtainedby the use of an automobile-type hydraulic jack equipped with a pressuregauge.7.4 Mercury and lead-foil electrodes give capacitance val-ues comparable with those obtained at the highest pressureswhen using
43、flat, steel electrodes (Note 6). Use clean mercurythat has a bright surface that is free of scum. Observe healthhazard precautions when using mercury, particularly at el-evated temperatures.NOTE 6In order to satisfactorily compare the dissipation factor andrelative permittivity of various specimens
44、of mica, it is advisable toinvestigate such properties over a wide frequency range. However, it isrecommended that at least one measurement be made at 1000 kHz and atemperature of 25 6 5C, at a pressure of 1000 psi if flat steel electrodesare used.8. Calculation8.1 Since two specimens are used in ea
45、ch measurementwhen using steel or mercury electrodes, use the equivalent“parallel thickness” in calculating the relative permittivity asfollows:Te5 1/1/t1!11/t2!# (1)where:Te= equivalent parallel thickness,t1= thickness of the upper specimen, andt2= thickness of the lower specimen.9. Report9.1 Repor
46、t the following information:9.1.1 Identification of the mica tested,9.1.2 The date of testing,9.1.3 The test conditions, including frequency of the appliedvoltage, specimen temperature during testing, voltage stress onthe specimen, relative humidity during testing, type, and size ofelectrodes used.9
47、.1.4 The applied pressure if flat steel electrodes are used,9.1.5 Capacitance of each specimen,9.1.6 The “parallel thickness” of each specimen,9.1.7 Aplot of dissipation factor versus pressure if flat, steelelectrodes are used,9.1.8 A plot of permittivity versus pressure if flat, steelelectrodes are
48、 used,9.1.9 The value of the dissipation factor and the relativepermittivity for each specimen,9.1.10 The method of measurement from Test MethodsD150, if applicable, and9.1.11 The method used if techniques from SpecificationD748 were used.10. Precision and Bias10.1 This test method has been in use f
49、or many years, but noinformation has been presented to ASTM upon which to basea statement of precision. No activity has been planned todevelop such information.10.2 BiasThis test method has no bias because the valuesfor dissipation factor and capacitance are determined solely interms of this test method.11. Keywords11.1 dissipation factor; mica; permittivity4The American Conference of Governmental Industrial Hygienists, Inc.(ACGIH), 1330 Kemper Meadow Dr., Suite 600, Cincinnati, OH 45240.D1082 173SUMMARY OF CHANGESCommittee D09 has i
