1、Designation: E1652 10Standard Specification forMagnesium Oxide and Aluminum Oxide Powder andCrushable Insulators Used in the Manufacture of Metal-Sheathed Platinum Resistance Thermometers, Base MetalThermocouples, and Noble Metal Thermocouples1This standard is issued under the fixed designation E165
2、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 reapprova
3、l.1. Scope1.1 This specification covers the requirements for magne-sium oxide (MgO) and aluminum oxide (Al2O3) powders andcrushable insulators used to manufacture metal-sheathed plati-num resistance thermometers (PRTs), noble metal thermo-couples, base metal thermocouples, and their respective cable
4、s.1.2 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 a
5、ppro-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,
6、andSpectrochemical 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 Soli
7、dMaterials 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 Th
8、ermocoupleCableE1137/E1137M Specification for Industrial Platinum Resis-tance ThermometersE1225 Test Method for Thermal Conductivity of Solids byMeans of the Guarded-Comparative-Longitudinal HeatFlow TechniqueE2181/E2181M Specification for Compacted Mineral-Insulated, Metal-Sheathed, Noble Metal The
9、rmocouplesand 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 Specification
10、s E235, E585/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 t
11、his purpose, 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.1This specification is under the jurisdiction of ASTM Committee E20 onTemperature Measurement a
12、nd is the direct responsibility of Subcommittee E20.04on Thermocouples.Current edition approved May 1, 2010. Published June 2010. Originallyapproved in 1995. Last previous edition approved in 2003 as E1652 03. DOI:10.1520/E1652-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org,
13、 orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.3 Use of this
14、 specification for the procurement of powderand crushable insulators will help to ensure that the productobtained is suitable for the intended purpose.4.4 Useful information about alumina and magnesia is givenin the appendixes.5. Classification5.1 The purchaser shall specify the appropriate Material
15、 andType 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 2 per Table 2, see 5.7.1.5.5 Al2O3Type 2 per Table 2, see 5.7.1.5.6 MgO Type 3 per Table 3, see 5.7.2.NOTE 1There is no corresponding Al2O3Type 3 designation at thistime.5.7 Background Information
16、 (previously appearing as foot-notes in earlier versions of the standard):5.7.1 Type 2 materials permit slightly higher Fe2O3contentthan Type 1 materials. The presence of Fe2O3can adverselyaffect the electrical resistivity of these insulators. Moreover,changes in the thermometric properties of plati
17、num and itsalloys that are exposed to Fe2O3concentrations above 0.04 %become more pronounced when exposed to the higher servicetemperatures, for example, above 650 C (1200 F), forprolonged periods. However, at lower service temperatures,purchaser may choose to allow Fe2O3concentrations of up to0.1 %
18、 in Al2O3or 0.15 % in MgO.5.7.2 Type 3 MgO materials permit significantly higherlevels of benign metal oxide species, and slightly higher Fe2O3content. Calcium oxide, aluminum oxide, and silicon oxide areno more likely than magnesium oxide to react deleteriouslywith the thermoelement alloys of base
19、metal thermocouples attemperatures that are recommended for the operation of thosethermoelement alloys. Therefore, optionally, for base metalthermocouples only, MgO insulators shall conform to thechemical requirements ofTable 3 instead ofTable 1.This oxidecomposition shall be designated MgO Type 3.5
20、.8 The final product shall be chemically analyzed usingappropriate methods listed in 9.1. Major impurities shall notexceed the limits indicated in Table 1 through Table 4 for theappropriate grade. Any detected impurity with a concentrationgreater than 0.001 % (mass) shall be reported to the purchase
21、r.6. Ordering Information6.1 The purchaser shall specify the 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 spe
22、cify the following additionalinformation when ordering:6.2.1 Minimum Inside Diameter (at Maximum MaterialCondition (MMC) of the Tubing, (into which insulators will beinserted, see 8.3).TABLE 1 Impurity Limits for Al2O3Type 1 and MgO Type 1AAluminum Oxide (Al2O3) 99.65 %(mass) minMagnesium Oxide (MgO
23、) 99.40 %(mass) minImpurityConcentration,% (mass)ImpurityConcentration,% (mass)Fe2O30.04 max CaO 0.35 maxSiO20.08 maxBAl2O30.15 maxCaO 0.08 max Fe2O30.04 maxMgO 0.08 max SiO20.13 maxBZrO20.08 max C 0.02 maxNa2O 0.06 max S 0.005 maxC 0.01 max B 0.0035 maxS 0.005 max Cd 0.001 maxCd 0.001 max B + Cd 0.
24、004 maxB 0.001 maxAThe total compositional analysis should equal 100 %.BThe presence of SiO2can, at elevated temperatures, lead to changes in theelectrical resistivity, thermoelectric characteristics and mechanical properties ofplatinum and its alloys.TABLE 2 Impurity Limits for Al2O3Type 2 and MgO
25、Type 2AAluminum Oxide (Al2O3) 99.65 %(mass) minMagnesium Oxide (MgO) 99.40 %(mass) minImpurityConcentration,% (mass) ImpurityConcentration,% (mass)Fe2O30.10 max CaO 0.35 maxSiO20.08 max Al2O30.15 maxCaO 0.08 max Fe2O30.15 maxMgO 0.08 max SiO20.13 maxZrO20.08 max C 0.02 maxNa2O 0.06 max S 0.005 maxC
26、0.01 max B 0.0035 maxS 0.005 max Cd 0.001 maxCd 0.001 max B + Cd 0.004 maxB 0.001 maxAThe total compositional analysis should equal 100 %.TABLE 3 Impurity Limits for MgO Type 3AMagnesium Oxide (MgO) 97.00 % (mass) minImpurity Concentration, % (mass)CaO 0.80 maxAl2O31.00 maxFe2O30.08 maxSiO21.20 maxF
27、e 0.02 maxC 0.02 maxS 0.005 maxB 0.0025 maxCd 0.001 maxB + Cd 0.003 maxMgO + CaO + Al2O3+SiO299.50 minAThe total compositional analysis should equal 100 %.TABLE 4 Outside Diameter (O.D.) TolerancesNominal Insulator O.D. O.D. ToleranceOver 0.25 to 1.00 mm (0.010 to 0.039 in.),inclusive60.05 mm (60.00
28、2 in.)Over 1.00 to 1.50 mm (0.039 to 0.059 in.),inclusive60.08 mm (60.003 in.)Over 1.50 to 5.00 mm (0.059 to 0.197 in.),inclusive60.10 mm (60.004 in.)Over 5.00 to 8.00 mm (0.197 to 0.315 in.),inclusive60.13 mm (60.005 in.)Over 8.00 to 10.00 mm (0.315 to 0.394 in.),inclusive60.15 mm (60.006 in.)Over
29、10.0 mm (0.394 in.) 61.75%E1652 1026.2.2 Maximum Outside Diameter of Wire which will beinserted into the insulators, (see 8.3).6.3 Consult the insulator manufacturer for limitations ofrelationships between outside diameter, hole diameters, holepatterns, and length.7. Physical Properties7.1 DensityTh
30、e 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 beused to determine density, shall be negotiated between thepurchaser and manufacturer. See A
31、ppendix 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 variationsin modulus from 21 to 83 MPa (3000 to 12 000 lb/in.2)influenced by insulator configur
32、ation, 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 sizeand configuration. See Appendix X4 for a suggested testmethod and X2.4 for recommended to
33、lerances.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 and manu-facturer.8.2 The wall and web thicknesses (see Fig. 1) shall be equalwithin outsi
34、de the total allowable outside diameter tolerance asspecified in Table 5 and the minimum measured web or wallshall be no smaller 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. Theinsu
35、lator shall be capable of passing through a rigid straighttube longer than the insulator and with an inside diameter asspecified in 6.2.1. Local camber defects caused by 9knees9 or9doglegs9 shall not impede the insertion of wire.8.4 The helical twist of holes shall not exceed 2 per cm (5per in.) of
36、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 each 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 a
37、nalysis, or fusion calorimetric analysis,or both, can be used for quantitative determination of silicondioxide (SiO2), iron 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 M
38、ethod C809 can be used for quantitative analy-sis of elemental impurities.9.1.3 Any method used for quantitative determinationshould 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 Appendi
39、x X5 lists other optional test methods.10. Handling and Storage Precautions10.1 Powders and crushable insulators shall be shipped andstored in containers that prevent contamination and breakage.Powders and crushable insulators should be stored in sealedcontainers to prevent contamination by moisture
40、 absorption.(See Appendix X2.)11. Keywords11.1 aluminum oxide; crushable; insulator; magnesium ox-ide; mineral-insulated, metal-sheathed cable; platinum resis-tance thermometer; thermocouple, base metal; thermocouple,noble metalTABLE 5 Hole Diameter ToleranceANominal Insulator Hole Diameter Hole Dia
41、meter ToleranceOver 0.18 to 1.00 mm (0.007 to 0.039 in.),inclusive60.05 mm (60.002 in.)Over 1.00 to 2.00 mm (0.040 to 0.079 in.),inclusive60.08 mm (60.003 in.)Over 2.00 to 2.50 mm (0.079 to 0.098 in.),inclusive60.10 mm (60.004 in.)Over 2.50 mm (0.098 in.) and larger,inclusive605 %ASee X2.3 for recom
42、mended inspection procedure.FIG. 1 Wall and Web ThicknessesE1652 103APPENDIXES(Nonmandatory Information)X1. MATERIALS AND MANUFACTUREX1.1 Alumina (Al2O3)X1.1.1 Sources:X1.1.1.1 Bauxite is the principal source of alumina. Gibb-site, Al(OH)3, is the most stable phase. Boehmite, AlO(OH),also occurs in
43、nature. High grade bauxite is low in iron andsilica content. The major use of purified alumina is in theproduction 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 acid, alkaline furnace, carbot
44、hermic 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 moredifficult to dissolve. It
45、 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” is sedimented or filtered o
46、ff. 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 trihydrate dehydrates first to
47、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 C (1000 F) for 7 h still resu
48、lted 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 alumina is a desiccant and is
49、 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 low 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 Expansion6 to9 3 106/K (3.3 to 5 3 106/F
