1、Designation:D 2773 94An American National StandardStandard Test Method forLoss on Ignition of Electrical Grade Magnesium Oxide1This standard is issued under the fixed designation D 2773;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision
2、,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 determination of the loss onignition of electrical grade magnesium oxide for use
3、insheathed heating units.1.2 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 and health practices and determine the applica-bility of regulatory limitations prior
4、to use.2.Referenced Documents2.1 ASTM Standards:D 2755 Test Method of Sampling and Reduction to TestWeight of Electrical Grade Magnesium Oxide23.Summary of Test Method3.1 The loss on ignition is the free and combined moisturetogether with any carbonaceous impurities that are volatilizedat 1000C,thei
5、r loss calculated as a percentage of the originalweight.4.Significance and Use4.1 Magnesium oxide,being a hygroscopic material,cancontain sufficient moisture that is detrimental to the manufac-turing process and performance of sheathed heating elements.5.Apparatus5.1 Balance,capable of weighing to 6
6、0.1 mg.5.2 Platinum Crucible,of 15-cm3capacity,with lid.5.3 Muffle Furnace,capable of 1000C temperature.5.4 Vacuum Desiccator.5.5 Vacuum Pump,capable of producing vacuum of 2 mm(266 Pa)Hg pressure.5.6 Tongs.6.Sampling6.1 Obtain a sample of magnesium oxide in accordance withTest Method D 2755.6.2 Fro
7、m the sample,take at least two specimens of 206 1g each.7.Procedure7.1 Heat the platinum crucible with lid at 1000 6 25C inthe muffle furnace for at least 10 min.Remove the cruciblefrom the furnace and cool to room temperature in a desiccator.Weigh the crucible and lid to the nearest 0.1 mg.7.2 Tran
8、sfer sample to the crucible,cover immediately witha lid,and weigh to the nearest 0.1 mg.7.3 Place the crucible with specimen in the muffle furnace at1000 6 25C,and ignite the sample for 1 h at this temperature.7.4 Remove the crucible from the furnace and place imme-diately in desiccator.Loosen the c
9、rucible lid and leave slightlyajar to allow for outgasing of the material during the evacua-tion process.Close the desiccator and apply vacuum.Evacuatethe desiccator to below 2 mm(266 Pa)Hg pressure(Note 1)and maintain vacuum until the sample is cooled to roomtemperature(Note 2).NOTE1Avoid sudden ev
10、acuation of the desiccator which could leadto dust loss.NOTE2Under normal conditions,a cooling period of at least 12 h isrequired.7.5 Remove the crucible with specimen and lid,and imme-diately weigh to the nearest 0.1 mg.7.6 Perform at least two determinations to obtain the aver-age loss on ignition
11、.8.Calculation8.1 Calculate the percentage loss on ignition as follows:Loss on ignition,%5B 2 C!/B 2 A!#3 100(1)where:A 5 weight of crucible,and lid,B 5 weight of crucible,lid and original sample,andC 5 weight of crucible,lid and ignited sample.9.Report9.1 Report the following information:9.1.1 Prop
12、er identification of the sample,and9.1.2 The average percent loss on ignition.1This test method is under the jurisdiction of ASTM Committee D-9 onElectrical and Electronic Insulating Materials and is the direct responsibility ofSubcommittee D09.14 on Electric Heating Unit Insulation.Current edition
13、approved June 15,1994.Published August 1994.Originallypublished as D 2773 69.Last previous edition D 2773 86.2Annual Book of ASTM Standards,Vol 10.02.1Copyright ASTM,100 Barr Harbor Drive,West Conshohocken,PA 19428-2959,United States.NOTICE:This standard has either been superceded and replaced by a
14、new version or discontinued.Contact ASTM International(www.astm.org)for the latest information.10.Precision and Bias10.1 The precision of this test method has not been deter-mined.In a well equipped laboratory with trained personnel,itis expected that duplicate determinations of loss on ignition ofa
15、 sample of magnesium oxide will agree within 65%of themean value.10.2 A statement of bias is not warranted due to the lack ofa standard specimen of magnesium oxide having a knownvalue of loss on ignition.11.Keywords11.1 loss on ignition;magnesium oxide;moistureThe American Society for Testing and Ma
16、terials takes no position respecting the validity of any patent rights asserted in connectionwith 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 technical committee and must be reviewed every five years andif not revised,either reapproved or withdrawn.Your
