1、Designation: D352 97 (Reapproved 2016)Standard Test Methods forPasted Mica Used in Electrical Insulation1This standard is issued under the fixed designation D352; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last rev
2、ision. 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 These test methods cover the testing of bonded micasplittings and bonded mica paper to be used for commutatorinsulation, hot m
3、olding, heater plates, and other similar insu-lating purposes.1.2 These test methods appear in the following sections:Test SectionsCompressive Creep 410Dielectric Strength 3841Mica or Binder Content 19Molding Test 3136Organic Binder 2024Resistivity 4246Silicone Binder 2530Stability Under Heat and Pr
4、essure 11181.3 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.4 This standard does not purport to address all of thesafety concerns, i
5、f 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. See 40.1 and 45.1for specific hazard statements.2. Referenced Documents2.1 ASTM Standard
6、s:2D149 Test Method for Dielectric Breakdown Voltage andDielectric Strength of Solid Electrical Insulating Materialsat Commercial Power FrequenciesD257 Test Methods for DC Resistance or Conductance ofInsulating MaterialsD1711 Terminology Relating to Electrical Insulation3. Terminology3.1 Definitions
7、:3.1.1 For definitions of terms relating to electricalinsulation, refer to Terminology D1711.3.2 Definitions of Terms Specific to This Standard:3.2.1 binder content, n, (of pasted mica)the percent byweight of binder relative to the original weight of a specimenas determined by procedures specified h
8、erein.3.2.1.1 DiscussionBinder content includes any residualsolvent. Pasted mica materials not fully cured (such as moldingand flexible plates) may contain appreciable quantities ofsolvent in the binder. This solvent is usually later removedwhen the material is cured in the manufacture of electrical
9、equipment. In such cases, the binder content after cure is less(by the amount of solvent removed) than would be determinedby this method. To determine the binder content after cure ofmaterials that are not fully cured, but subsequently will be, it isnecessary, before initially weighing the specimen,
10、 to heat thespecimen for a time and at a temperature that depends upon thematerial from which the specimen is prepared.3.2.2 compressive creep, nthe change in thickness of abonded micaceous material resulting from exposure to elevatedtemperature for a specified time while a specimen is under aspecif
11、ied compressive load.3.2.3 mica content, n, (of pasted mica)the percent byweight of mica relative to the original weight equal to 100 %minus the binder content as determined by procedures specifiedherein.COMPRESSIVE CREEP4. Significance and Use4.1 This test determines the compressive creep under lab
12、o-ratory conditions or under conditions that may be encounteredduring manufacture of electrical equipment. It has specialsignificance if the material to be tested is applied as commu-tator segment insulation. It serves as a measure under specifiedconditions of the ability of the material to resist d
13、eformationwhile under compressive load, during exposure to elevatedtemperature for a specified time. This test is suitable foracceptance tests and for manufacturing control.1These test methods are under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and are t
14、he direct responsibility ofSubcommittee D09.19 on Dielectric Sheet and Roll Products (Disbanded 4/2016).Current edition approved May 15, 2016. Published May 2016. Originallyapproved in 1932. Last previous edition approved in 2008 as D352 97 (2008)1.DOI: 10.1520/D0352-97R16.2For referenced ASTM stand
15、ards, 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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA
16、 19428-2959. United States15. Apparatus5.1 Hydraulic PressA hydraulic press having temperaturecontrolled, electrically heated platens, or a press with otherprovisions for heating the specimen and controlling the tem-perature. The platens shall be at least 4 by 4 in. (102 by 102mm) in size. The press
17、 shall be capable of exerting a force ofat least 4000 lb (18 kN). The apparatus shall be capable ofmaintaining a specimen temperature of at least 200 6 5C. Itis preferable that the apparatus have platens with water ducts orother provisions for cooling the specimen. (See Note 1 in 7.3.)5.2 Pressure G
18、ageApressure gage capable of determiningthe pressure on the specimen with an accuracy of 65%.5.3 Thickness GageA thickness gage capable of measur-ing the thickness of the specimen to the nearest 0.001 in. (0.025mm).5.4 PotentiometerTemperature measuring instrument anda No. 30 AWG or smaller thermoco
19、uple with overall accuracyof 6 2C for measurement of specimen temperature.5.5 Steel PlatesTwo 4 by 4-in. (102 by 102-mm) or largerpolished steel plates of at least116-in. (1.6-mm) thickness,surface ground so that the top and bottom surfaces of eachpiece are parallel, one plate each for the top and b
20、ottom of thetest specimen.6. Test Specimen6.1 The test specimen shall consist of a sufficient number ofpieces of bonded micaceous plate, 2 by 2 in. (51 by 51 mm) insize, to form a stack approximately but not greater than 1.000in. (25.40 mm) in thickness. The pieces shall be selected so asto be repre
21、sentative of the entire sheet.At least three specimensshall be tested for each lot of material.7. Procedure7.1 Center the stacked specimen between the 4 by 4-in. (102by 102-mm) steel plates and then center this assembly in thepress. Place the thermocouple between pieces near the middleof the stack.
22、Carefully align the stack to form a right parallel-epiped. Apply a pressure of 1000 psi (7 MPa) to the specimensurfaces, and carefully determine the average thickness of thestack by means of the gage. Where inside gages are used,measure the thickness at each of the four corners as close to thespecim
23、en as possible. Measurements shall be made within 5min.7.2 Pack approximately 2 in. (51 mm) of thermal insulationmaterial around the specimen without disturbing it. Heat thespecimen to 160 6 5C or 200 6 5C as specified. The timerequired to reach the specified temperature should be not lessthan 30 mi
24、n nor more than 75 min. The platen temperatureshall not exceed the specified temperature by more than thespecified tolerance. If the specimen is heated by other means,the surrounding medium shall not exceed the specified tem-perature by more than the specified tolerance. Allow thespecimen to remain
25、at the specified temperature for 2 h afterreaching that temperature, and at the same time maintain the1000-psi pressure.7.3 Remove the thermal insulation and, while maintainingthe pressure, allow the specimen to cool until the temperatureis 5C above the temperature (room ambient) at which theorigina
26、l thickness was measured. Control the rate of coolingsuch that it does not exceed the rate at which the temperaturewas raised. Then determine the thickness of the stack whileunder 1000-psi compressive load.NOTE 1Experience has shown that in order to cool the specimen to thespecified temperature with
27、in a reasonable time, forced-cooling meansmust be employed. It is suggested that a fan be initially utilized to forceair across the specimen for the first 5 min, after which cooling water maybe allowed to circulate in ducts provided in the platens. The rate of waterflow, if used, should be adjusted
28、to give a cooling rate no greater than therate at which the specimen was initially heated.8. Calculation8.1 Calculate the percentage compressive creep, C, as fol-lows:C,%5 T 2 T!/T# 3100 (1)where:T = thickness of the stack at 1000 psi (7 MPa) beforeheating, andT = thickness of the stack at 1000 psi
29、after heating.9. Report9.1 Report the following information:9.1.1 The identity of the material,9.1.2 The nominal thickness of the pasted mica,9.1.3 The observed values of T and T,9.1.4 The percentage compressive creep, and9.1.5 The specimen temperature.10. Precision and Bias10.1 This method has been
30、 in use for many years but nostatement for precision has been made and no activity isplanned to develop such a statement.10.2 A statement of bias is not possible due to a lack of astandard reference material.STABILITY UNDER HEAT AND PRESSURE11. Scope11.1 The test for stability under heat and pressur
31、e deter-mines mica or binder displacement, or both, under the specifiedconditions of test.12. Significance and Use12.1 This test serves as a measure of the ability of bondedmicaceous materials to maintain their physical integrity underexposure to heat and pressure. It has special significance wheret
32、he material to be tested is employed as commutator segmentinsulation. This test is suitable for acceptance tests and formanufacturing control.13. Nature of Test13.1 This test method utilizes the application of a shearingforce as well as a compressive force, which is accomplished byplacing the specim
33、ens between specified wedges, therebyD352 97 (2016)2causing the applied force to resolve into compression and shearcomponents. This test is particularly useful for material used incommutator assemblies where shearing as well as compressiveforces are encountered. Test results are expressed quantita-t
34、ively as units of linear deflection.14. Apparatus14.1 Hydraulic Press, Pressure Gage, and Thermocouple asdescribed in Section 5, except that the hydraulic press shall becapable of producing a force of 26 400 lb (118 kN) on thespecimen,14.2 Steel WedgesTwo steel wedges of the same size asthe specimen
35、 by approximately34 in. (19 mm) thick, with oneface tapered at an angle of 3 with the horizontal and a centerwedge as shown in Fig. 1. They shall be hardened and surfaceground top and bottom.14.3 Dial GagesTwo dial gages having 0.001-in. (0.02-mm) graduations and a range of at least12-in. (13-mm),de
36、signed to be accurate at the specified test temperature, andsuitably mounted on the steel wedges described in 14.2.NOTE 2Where the dial gages are mounted through nonmetallicbushings, or if some other suitable method is used to interrupt the metallicthermal path, it shall not be necessary to utilize
37、gages designed to beaccurate at the test temperature.15. Test Specimen15.1 The specimen shall consist of two rectangular pieces ofbonded micaceous plate between 4 and 6 in.2(2580 and 3870mm2) in area, the shorter side being not less than 112 in. (38mm).16. Procedure16.1 Insert the specimen between t
38、he wedges, as shown inFig. 1. Center the assembly in the press and carefully align,using just enough pressure to hold the assembly together. Insertthe thermocouple and fit it tightly in the hole provided in thecenter wedge. Cement the thermocouple into the hole. Apply apressure of 100 6 10 psi (690
39、6 70 kPa) on the top and bottomassembly surfaces.16.2 Pack approximately 2 in. (51 mm) of thermal insulat-ing material, such as glass or other inorganic fiber mat, aroundthe specimen without disturbing either the specimen or dialgages. Heat the specimen to 160 6 5C or 200 6 5C, asspecified, and allo
40、w to remain at the specified temperature for5 +1, 0 min. Do not allow the platen temperature to exceedthe specimen temperature by more than 10C.16.3 Adjust both gages to read zero. Apply and hold apressure of 4400 psi (30 MPa) within5sonthetopandbottomassembly surfaces and maintain for 15 min at the
41、 specifiedtemperature. Record the deflection as determined by the topand bottom dial gages after 15 s, 30 s, 1, 2, 5, 10, and 15 minbeginning with the instant that the 4400 psi pressure isobtained.17. Report17.1 Report the following information:17.1.1 The identity of the material,17.1.2 The dimensio
42、ns of the specimen used,17.1.3 The temperature used, and17.1.4 The average deflection at each of the time intervals inaccordance with 16.3.18. Precision and Bias18.1 See 10.1.18.2 See 10.2.MICA OR BINDER CONTENT19. Significance and Use19.1 Physical (such as the ability to hot mold, flexibility)and e
43、lectrical (such as dielectric strength, resistivity) propertiesof bonded micaceous materials are affected, among otherthings, by the proportional contents of the binder and mica.Themethods for mica or binder content are suitable for acceptancetests and manufacturing control.ORGANIC BINDER20. Apparat
44、us20.1 BurnerBunsen burner or muffle furnace.20.2 DishesPlatinum or porcelain dishes or crucibles.21. Test Specimen21.1 Specimens from PlatesFrom a plate, cut a sufficientnumber of individual pieces in accordance with Fig. 2 to obtaina composite specimen weighing 5 to 10 g.Minimum size of sheet: A =
45、 3 in.; B =18in.FIG. 1 Apparatus for Stability Test Under Heat and Pressure, An-gular MethodFIG. 2 Pattern for Location of Test Pieces for Determination ofMica of Binder ContentD352 97 (2016)321.2 Specimens From Fabricated PartsFrom a lot, take arepresentative test specimen weighing 5 to 10 g.22. Pr
46、ocedure22.1 WarningThis test method involves the use of heat toremove organic material which in a gaseous state may behazardous. Conduct this test under a hood equipped withadequate ventilation. Alternatively, a muffle furnace with anadequate exhaust system may be used to burn off the mica untilit i
47、s carbon free.22.2 Weigh each specimen to the nearest 0.001 g in a tareddish or crucible.22.3 Place the dish with the specimen over a bunsen burneror in a muffle furnace and heat at a low red heat (to avoid thedehydration of mica) until all the organic material and carbonare burned off. After coolin
48、g in a desiccator, determine theweight of the residue.23. Report23.1 Report the following information:23.1.1 The identity of the material,23.1.2 Percentage loss in weight of each specimen indicatedas binder, and23.1.3 Percentage of residue in the crucible indicated asmica.24. Precision and Bias24.1
49、See 10.1.24.2 See 10.2.SILICONE BINDER25. Apparatus25.1 Gooch Crucible, containing a prewashed, dried, andweighed glass fiber mat (see Fig. 3).25.2 Beaker, 500-mL, alkali-resistant.25.3 Condenser, for condensing reagent vapors.25.4 FlaskSuction flask, 500-mL, alkali-resistant, fittedwith Gooch crucible adaptor.25.5 Hot Plate, for boiling solvent mixture.NOTE 3It is not necessary to use the glass fiber mat of 25.1 if a testspecimen contains bonded mica splittings.26. Reagents26.1 Butyl Alcohol, normal, cp grade.26.2 Toluol, cp grade.26
