1、Designation: E1652 14Standard Specification forMagnesium Oxide and Aluminum Oxide Powder andCrushable Insulators Used in the Manufacture of Base MetalThermocouples, Metal-Sheathed Platinum ResistanceThermometers, and Noble Metal Thermocouples1This standard is issued under the fixed designation E1652
2、; the number immediately following the designation 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
3、.1. Scope1.1 This specification covers the requirements for magne-sium oxide (MgO) and aluminum oxide (Al2O3) powders andcrushable insulators used to manufacture base metalthermocouples, metal-sheathed platinum resistance thermom-eters (PRTs), noble metal thermocouples, and their respectivecables.1.
4、2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 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
5、-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B329 Test Method for Apparent Density of Metal Powdersand Compounds Using the Scott VolumeterC809 Test Methods for Chemical, Mass Spectrometric, andS
6、pectrochemical Analysis of Nuclear-Grade AluminumOxide and AluminumOxide-Boron Carbide CompositePelletsC832 Test Method of Measuring Thermal Expansion andCreep of Refractories Under LoadD2766 Test Method for Specific Heat of Liquids and SolidsE228 Test Method for Linear Thermal Expansion of SolidMat
7、erials With a Push-Rod DilatometerE235 Specification for Thermocouples, Sheathed, Type Kand Type N, for Nuclear or for Other High-ReliabilityApplicationsE344 Terminology Relating to Thermometry and Hydrom-etryE585/E585M Specification for Compacted Mineral-Insulated, Metal-Sheathed, Base Metal Thermo
8、coupleCableE1137/E1137M Specification for Industrial Platinum Resis-tance ThermometersE1225 Test Method for Thermal Conductivity of SolidsUsing the Guarded-Comparative-Longitudinal Heat FlowTechniqueE2181/E2181M Specification for Compacted Mineral-Insulated, Metal-Sheathed, Noble Metal Thermocouples
9、and Thermocouple Cable3. Terminology3.1 The definitions given in Terminology E344 shall applyto this specification.4. Significance and Use4.1 Magnesium oxide and aluminum oxide are used toelectrically isolate and mechanically support the thermoele-ments of a thermocouple (see Specifications E235, E5
10、85/E585M, and E2181/E2181M) and the connecting wires of aPRT (see Specification E1137/E1137M) within a metal sheath.The metal sheath is typically reduced in diameter to compactthe oxide powder or crushable oxide insulators around thethermoelements or wires.4.2 In order to be suitable for this purpos
11、e, the materialsshall meet certain criteria for purity and for mechanical anddimensional characteristics. Material that does not meet thepurity criteria may cause premature failure of the sensor.4.3 Use of this specification for the procurement of powderand crushable insulators will help to ensure t
12、hat the productobtained is suitable for the intended purpose.4.4 Useful information about alumina and magnesia is givenin the appendixes.1This specification is under the jurisdiction of ASTM Committee E20 onTemperature Measurement and is the direct responsibility of Subcommittee E20.04on Thermocoupl
13、es.Current edition approved Jan. 15, 2014. Published February 2014. Originallyapproved in 1995. Last previous edition approved in 2010 as E1652 10. DOI:10.1520/E1652-14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annua
14、l 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 19428-2959. United States15. Classification5.1 The purchaser shall specify the appropriate Material andT
15、ype from 5.2 through 5.6 below.5.2 MgO Type 1 per Table 1.5.3 Al2O3Type 1 per Table 1.5.4 MgO Type 1P per Table 2.5.5 Al2O3Type 1P per Table 2.5.6 MgO Type 2 per Table 3.NOTE 1There is no corresponding Al2O3Type 2 designation at thistime.5.7 The final product shall be chemically analyzed usingapprop
16、riate methods listed in 9.1. Major impurities shall notexceed the limits indicated in Table 1 through Table 3 for theappropriate grade. Any detected impurity with a concentrationgreater than 0.001 % (mass) shall be reported to the purchaser.6. Ordering Information6.1 The purchaser shall specify the
17、following when order-ing:6.1.1 Material and Type per Section 5.6.1.2 Insulator Outside Diameter.6.1.3 Hole Diameter.6.1.4 Number of Holes.6.1.5 Hole Pattern.6.1.6 Length.6.1.7 Particle Size (if supplied as powder).6.2 The purchaser may specify the following additionalinformation when ordering:6.2.1
18、Minimum Inside Diameter (at Maximum MaterialCondition (MMC) of the Tubing, (into which insulators will beinserted, see 8.3).6.2.2 Maximum Outside Diameter of Wire which will beinserted into the insulators, (see 8.3).6.3 Consult the insulator manufacturer for limitations ofrelationships between outsi
19、de diameter, hole diameters, holepatterns, and length.7. Physical Properties7.1 DensityThe density of crushable magnesium oxideand aluminum oxide insulators typically ranges from 2060kg/m3(0.074 lbm/in.3) to 3060 kg/m3(0.111 lbm/in.3).Specific density requirements, as well as the test method to beus
20、ed to determine density, shall be negotiated between thepurchaser and manufacturer. See Appendix X3 for suggestedtest methods.7.2 Modulus of Rupture (MOR)In the past, a breakingforce test that is based on a relative modulus of rupture and isrelated to crushability has been used. However, with variat
21、ionsin modulus from 21 to 83 MPa (3000 to 12 000 lb/in.2)influenced by insulator configuration, number of holes, andcross-sectional dimensions, specific modulus requirementscannot be listed for each configuration. The modulus of ruptureis best used for lot-to-lot comparison of a given insulator size
22、and configuration. See Appendix X4 for a suggested testmethod and X2.4 for recommended tolerances.8. Dimensional Requirements8.1 Outside diameter and hole diameter tolerances for insu-lators shall be as specified in Table 4 and Table 5, respectively,unless otherwise agreed to between the purchaser a
23、nd manu-facturer.8.2 The wall and web thicknesses (see Fig. 1) shall be equalwithin outside the total allowable outside diameter tolerance asTABLE 1 Chemical Requirements for Al2O3Type 1and MgO Type 1A, BAluminum Oxide (Al2O3) Magnesium Oxide (MgO)ImpurityConcentration,% (mass)ImpurityConcentration,
24、% (mass)Al2O3 99.65 % min MgO 99.40 % minCaO 0.08 max CaO 0.35 maxSiO2 0.08 maxBSiO2 0.13 maxBMgO 0.08 max Al2O3 0.15 maxFe2O3 0.04 max Fe2O3 0.07 maxZrO2 0.08 maxNa2O 0.06 maxC 0.01 max C 0.02 maxS 0.005 max S 0.005 maxB 0.001 max B 0.0035 maxCd 0.001 max Cd 0.001 maxB+Cd 0.004 maxAPlatinum thermoe
25、lements and Noble Metal thermocouples for use above 650Cshall specify Type 1P composition according to Table 2.BBase metal thermocouples for nuclear environments in accordance with Speci-fication E235 shall specify Type 1P composition according to Table 2.TABLE 2 Chemical Requirements for Al2O3Type
26、1Pand MgO Type 1PAAluminum Oxide (Al2O3) 99.65 %(mass) minMagnesium Oxide (MgO) 99.40 %(mass) minImpurityConcentration,% (mass) ImpurityConcentration,% (mass)Al2O3 99.65 % min MgO 99.40 % minCaO 0.08 max CaO 0.35 maxSiO2 0.08 max SiO2 0.13 maxMgO 0.08 max Al2O3 0.15 maxFe2O3 0.04 max Fe2O3 0.04 maxZ
27、rO2 0.08 maxNa2O 0.06 maxC 0.01 max C 0.02 maxS 0.005 max S 0.005 maxB 0.08 max B 0.0035 maxCd 0.08 max Cd 0.001 maxB+Cd 0.004 maxAPlatinum thermoelements and noble Metal thermocouples for use below 650Cmay optionally specify Type 1 composition according to Table 1.TABLE 3 Chemical Requirements for
28、MgO Type 2Magnesium Oxide (MgO)Impurity Concentration, % (mass)MgO 97.00 % minCaO 1.50 maxAl2O31.00 maxSiO23.50 maxFe2O30.15 maxC 0.02 maxS 0.005 maxB 0.0050 maxCd 0.001 maxB + Cd 0.0050 maxMgO + CaO + Al2O3+SiO299.50 minE1652 142specified in Table 5 and the minimum measured web or wallshall be no s
29、maller than 75 % of the maximum measured webor wall, unless otherwise agreed to between the purchaser andmanufacturer.8.3 The camber shall not exceed 0.3 % of the length. Theinsulator shall be capable of passing through a rigid straighttube longer than the insulator and with an inside diameter asspe
30、cified in 6.2.1. Local camber defects caused by “knees“ or“doglegs“ shall not impede the insertion of wire.8.4 The helical twist of holes shall not exceed 2 per cm (5per in.) of the length.8.5 The length shall be as specified in 6.1.6 with a toleranceof +6/0.00 mm ( +0.25/0.00 in.).8.6 The ends of e
31、ach insulator should be cut square andshall be essentially chip-free as agreed upon between thesupplier and purchaser.9. Test Methods9.1 Chemical Composition:9.1.1 Wet chemical analysis, or fusion calorimetric analysis,or both, can be used for quantitative determination of silicondioxide (SiO2), iro
32、n oxide (Fe2O3), and zirconium oxide(ZrO2) with gravimetric determination for SiO2and Fe2O3.The SiO2filtrate can be used for further calcium oxide (CaO)determination.9.1.2 Test Method C809 can be used for quantitative analy-sis of elemental impurities.9.1.3 Any method used for quantitative determina
33、tionshould have a detection sensitivity of at least 0.001 % (mass).9.2 Density (Powder)Test Method B329 can be used fordetermining the density of Al2O3and MgO powders.9.3 Appendix X5 lists other optional test methods.10. Handling and Storage Precautions10.1 Powders and crushable insulators shall be
34、shipped andstored in containers that prevent contamination and breakage.Powders and crushable insulators should be stored in sealedcontainers to prevent contamination by moisture absorption.(See Appendix X2.)11. Keywords11.1 aluminum oxide; crushable; insulator; magnesium ox-ide; mineral-insulated,
35、metal-sheathed cable; platinum resis-tance thermometer; thermocouple, base metal; thermocouple,noble metalTABLE 4 Outside Diameter (O.D.) TolerancesNominal Insulator O.D. O.D. ToleranceOver 0.25 to 1.00 mm (0.010 to 0.039 in.),inclusive0.05 mm (0.002 in.)Over 1.00 to 1.50 mm (0.039 to 0.059 in.),inc
36、lusive0.08 mm (0.003 in.)Over 1.50 to 5.00 mm (0.059 to 0.197 in.),inclusive0.10 mm (0.004 in.)Over 5.00 to 8.00 mm (0.197 to 0.315 in.),inclusive0.13 mm (0.005 in.)Over 8.00 to 10.00 mm (0.315 to 0.394 in.),inclusive0.15 mm (0.006 in.)Over 10.0 mm (0.394 in.) 1.75%TABLE 5 Hole Diameter ToleranceANo
37、minal Insulator Hole Diameter Hole Diameter ToleranceOver 0.18 to 1.00 mm (0.007 to 0.039 in.),inclusive0.05 mm (0.002 in.)Over 1.00 to 2.00 mm (0.040 to 0.079 in.),inclusive0.08 mm (0.003 in.)Over 2.00 to 2.50 mm (0.079 to 0.098 in.),inclusive0.10 mm (0.004 in.)Over 2.50 mm (0.098 in.) and larger,i
38、nclusive05 %ASee X2.3 for recommended inspection procedure.FIG. 1 Wall and Web ThicknessesE1652 143APPENDIXES(Nonmandatory Information)X1. MATERIALS AND MANUFACTUREX1.1 Alumina (Al2O3)X1.1.1 Sources:X1.1.1.1 Bauxite is the principal source of alumina.Gibbsite, Al(OH)3, is the most stable phase. Boeh
39、mite,AlO(OH), also occurs in nature. High grade bauxite is low iniron and silica content. The major use of purified alumina is inthe production of aluminum metal.X1.1.1.2 Depending upon the application, the economics,and the purity of the bauxite, the purification process could bewet alkaline, wet a
40、cid, alkaline furnace, carbothermic furnace,or electrolytic processes.X1.1.1.3 The wet alkaline processes are the most economi-cal. Gibbsite bauxite is easier to dissolve. It is digested insodium hydroxide (NaOH) solution at about 150 C (302 F) at345 kPa (50 lb/in.2). Boehmitic bauxite, AlO(OH), is
41、moredifficult to dissolve. It requires a higher concentration of NaOHsolution, a pressure of 1930 to 4826 kPa (280 to 700 lb/in.2),and a temperature of about 238 C (545 F).X1.1.1.4 When digested, the slurry is cooled to about100 C (212 F) by releasing pressure to atmospheric, and theundissolved “mud
42、” is sedimented or filtered off. When cooledto about 50 C (122 F) and seeded with alumina-trihydrate,precipitation occurs. The precipitated trihydrate is washed andthen calcinated. The trihydrate dehydrates slowly. At atmo-spheric pressures, the dehydration process involves two steps.X1.1.1.5 The tr
43、ihydrate dehydrates first to a compositionclose to boehmite (Al2O3H2O). Even at 200 C (392 F) therate of dehydration is very slow. Dehydration is essentiallycomplete at 400 C (752 F) in an oven at below atmosphericpressure or at 500 C (932 F) at atmospheric pressure. In onestudy, the heating at 538
44、C (1000 F) for 7 h still resulted in0.1 moles of H2O per mole Al2O3, that is, about 2 %.Differential thermal analysis (DTA) studies show endothermiceffects at 225, 300, and 550 C (437, 572, and 1022 F,respectively). The peak at 550 C (1022 F) represents thedehydration of boehmite.X1.1.1.6 Activated
45、alumina is a desiccant and is more easilyrehydrated when activated in vacuum. Alumina activated invacuum at 180 to 200 C (356 to 392 F) and then heated in airat about 350 to 450 C (662 to 842 F) does not rehydrate aseasily. No rehydration was found with alpha alumina of lowsurface area.To achieve lo
46、w surface area the alumina should beheated to at least 1700 C (3092 F). Alumina is sintered atabout 1700 to 2000 C (3092 to 3632 F). It melts around2050 C (3722 F).X1.1.2 Typical Crystal Properties :X1.1.2.1 Coeffcient of Thermal Expansion6to9106/K (3.3 to 5 106/F) between 20 and 1000 C (68and 1832
47、F).X1.1.2.2 Crystal Shape Hexagonal.X1.1.2.3 Maximum Theoretical Density3.98 103kg/m3(0.144 lbm/in3).X1.1.2.4 Dielectric Strength5600 kV/m (142 000 V/in).X1.1.2.5 Hardness (MOHS)9.X1.1.2.6 Softening Temperature1750 C (3182 F).X1.1.2.7 Melting Temperature2050 C (3722 F).X1.1.2.8 Molecular Weight101.9
48、4.X1.1.2.9 Typical Electrical ResistivitySee Table X1.1.X1.1.2.10 Specific Heat 8.8102J/kgK 20 C (0.21Btu/lbm F 68 F). 1.2 103J/kgK 1000 C (0.28Btu/lbm F 1832 F).X1.1.2.11 Typical Thermal Conductivity See Table X1.2.X1.1.2.12 Macroscopic Thermal Neutron Absorption CrossSection1.0 m1(0.03 in1).X1.2 M
49、agnesia (MgO)X1.2.1 Sources:X1.2.1.1 Magnesia can be made by the oxidation of mag-nesium metal or by heating easily decomposed oxy-compoundsof magnesium, such as the hydroxide, Mg(OH)2, the oxalate,MgC2O4, or the naturally occurring carbonate (magnesite),MgCO3. Mg(OH)2exists as the mineral brucite in smallamounts; however the principal commercial source of magne-sia is magnesite, which occurs in a relatively pure state in manyparts of the world. Another source of magnesia is
