1、Designation:D 4352 90(Reapproved 1997)e1An American National StandardStandard Test Method forDetermination of Magnetic Material Impurities in ElectricalGrade Magnesium Oxide1This standard is issued under the fixed designation D 4352;the number immediately following the designation indicates the year
2、 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.e1NOTE Keywords were added editorially in October 1997.1.Scope1.1 This te
3、st method covers the determination of magneticmaterial content of fused electrically insulating magnesiumoxide powders.1.2 The values stated in acceptable metric units are to beregarded as the standard.1.3 This standard does not purport to address the safetyproblems associated with its use.It is the
4、 responsibility of theuser of this standard to establish appropriate safety and healthpractices and determine the applicability of regulatory limita-tions prior to use.2.Referenced Documents2.1 ASTM Standards:D 2755 Test Method for Sampling and Reduction to TestWeight of Electrical Grade Magnesium O
5、xide23.Summary of Test Method3.1 A sample of electrical grade magnesium oxide is placedinto the magnetic analyzer sample tube.The magnetic materi-als content is then read directly as percent contained.4.Significance and Use4.1 Free iron in magnesium oxide powder is detrimental toelectrical character
6、istics of the powder when used as electricalinsulation in heating elements.5.Apparatus5.1 Magnetic Analyzer and Instrument Calibration Stan-dards.35.2 Laboratory Balance,capable of weighing 130 6 0.1 g.6.Calibration and Standardization6.1 The magnetics analyzer should be calibrated accordingto the i
7、nstrument instructions manual.NOTE1This procedure may vary somewhat when using an analyzerother than the Netronics Magnetics Analyzer.7.Procedure7.1 Obtain a sample to be tested in accordance with TestMethod D 2755.7.2 Weigh a 130 6 0.1 g specimen.7.3 Set sample weight dial to 130.7.4 Set range sele
8、ctor switch to 0.1.7.5 Zero instrument with empty sample tube using the nulladjustment.7.6 Transfer test sample to sample tube.7.7 Insert sample tube into sample compartment of theinstrument and read percent magnetics content directly fromdisplay meter.8.Report8.1 Report the following:8.1.1 Identifi
9、cation of the sample,and8.1.2 Percentage magnetic material to nearest 0.001%.9.Precision and Bias9.1 This test method is repeatable to within 64%ofmeasured value.9.2 This test method has been found to demonstrate a bias of81%at 0.01%to 95%at 0.10%magnetic iron relative to thetrue value.10.Keywords10
10、.1 electricalgrade;magnesiumoxide;magneticimpurities1This method is under the jurisdiction of ASTM Committee D-9 on Electricaland Electronic Insulating Materials and is the direct responsibility of SubcommitteeD09.14 on Electric Heating Unit Insulation.Current edition approved Nov.30,1990.Published
11、January 1991.Last previousedition D 4352 84.2Annual Book of ASTM Standards,Vol 10.02.3Model MA-1010A,obtainable from Buck and Co.,Inc.,345 Grove St.,P.O.Box 468,Franklin,MA 03038,or equivalent.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United Stat
12、es.NOTICE:This standard has either been superceded and replaced by a new version or discontinued.Contact ASTM International(www.astm.org)for the latest information.The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connectionwith
13、 any item mentioned in this standard.Users of this standard are expressly advised that determination of the validity of any suchpatent rights,and the risk of infringement of such rights,are entirely their own responsibility.This standard is subject to revision at any time by the responsible technica
14、l committee and must be reviewed every five years andif not revised,either reapproved or withdrawn.Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM Headquarters.Your comments will receive careful consideration at a meeting of t
15、he responsibletechnical committee,which you may attend.If you feel that your comments have not received a fair hearing you should make yourviews known to the ASTM Committee on Standards,at the address shown below.This standard is copyrighted byASTM,100 Barr Harbor Drive,PO Box C700,West Conshohocken
16、,PA19428-2959,United States.Individual reprints(single or multiple copies)of this standard may be obtained by contacting ASTM at the above address or at610-832-9585(phone),610-832-9555(fax),or serviceastm.org(e-mail);or through the ASTM website(www.astm.org).D 43522NOTICE:This standard has either been superceded and replaced by a new version or discontinued.Contact ASTM International(www.astm.org)for the latest information.