1、Designation: C 863 00 (Reapproved 2005)Standard Test Method forEvaluating Oxidation Resistance of Silicon CarbideRefractories at Elevated Temperatures1This standard is issued under the fixed designation C 863; the number immediately following the designation indicates the year oforiginal adoption or
2、, 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.1. Scope1.1 This test method covers the evaluation of the oxidationresistance of silicon c
3、arbide refractories at elevated tempera-tures in an atmosphere of steam. The steam is used toaccelerate the test. Oxidation resistance is the ability of thesilicon carbide (SiC) in the refractory to resist conversion tosilicon dioxide (SiO2) and its attendant crystalline growth.1.2 This standard doe
4、s 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 to use.2. Referenced Documents2.1 ASTM Stan
5、dards:2C20 Test Methods for Apparent Porosity, Water Absorp-tion, Apparent Specific Gravity, and Bulk Density ofBurned Refractory Brick and Shapes and Shapes byBoiling WaterC 830 Test Methods for Apparent Porosity, Liquid Absorp-tion, Apparent Specific Gravity, and Bulk Density ofRefractory Shapes b
6、y Vacuum PressureC 914 Test Method for Bulk Density and Volume of SolidRefractories by Wax Immersion3. Significance and Use3.1 The oxidation of silicon carbide refractories at elevatedtemperatures is an important consideration in the application ofthese refractories. The product of oxidation is amor
7、phous silicaor cristobalite, depending upon the temperature at whichoxidation takes place. This oxide formation is associated withexpansion and degradation of strength. The quantity of watervapor in the atmosphere greatly affects the rate of oxidation.3.2 The test, which creates and measures the exp
8、ansion, issuitable for guidance in product development and relativecomparison in application work where oxidation potential is ofconcern. The variability of the test is such that it is notrecommended for use as a referee test.4. Apparatus4.1 Heated ChamberThe chamber shall be muffled (Note1) to conf
9、ine the atmosphere. The size of the chamber and theheat source are optional. The temperature capability within thechamber shall be at least 1200C (2190F) with an allowabledeviation of 615C (27F) measured across the hearth.NOTE 1Silicon carbide refractory material is recommended for use asthe muffle
10、but other suitable refractory materials may be used.4.2 InstrumentControl and record the temperature of thechamber by a suitable instrument capable of maintaining therequirements in 4.1. Recommended thermocouple location iswithin 1 in. (25 mm) of the top of the specimens and over thecenter of the sa
11、me assemblage.5. Test Specimen5.1 Specimen SizeObtain a quarter-brick size from a229-mm (9-in.) straight by cutting the brick along planesparallel to both the 229 by 64-mm (9 by 212-in.) and the 114 by64-mm (412 by 212-in.) faces. Alternative specimens may betile, 165 by 114 by 22 mm (612 by 412 by7
12、8 in.), or otherconvenient shapes.5.2 Three specimens are required for each set of conditions.6. Conditions6.1 AtmosphereSteam is passed into the chamber (4.1)atthe rate of 32 kg/m3(2 lb/ft3) of chamber volume per hour.Provisions should be made to uniformly distribute steam withinthe chamber.6.2 The
13、 standard test temperatures are as follows with newsamples used at each temperature. Each temperature consti-tutes a test.800C (1470F)1This test method is under the jurisdiction of ASTM Committee C08 onRefractories and is the direct responsibility of Subcommittee C08.04 on ChemicalBehaviors.Current
14、edition approved Dec. 1, 2005. Published December 2005. Originallyapproved in 1977. Last previous edition approved in 2000 as C 863 00.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume inf
15、ormation, 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.900C (1650F)1000C (1830F)1100C (2010F)1200C (2190F)The test temperature is selected on the basis of the specifi
16、cneeds that relate to the environment in which the product is toserve. The use of at least the three test temperatures 900C,1000C, and 1100C is recommended when characterization ofthe product is desired.6.3 DurationHold at the specified temperature for 500 h.7. Procedure7.1 Measure the weight and vo
17、lume of each specimen to60.1 g and 60.1 cm3, respectively, in accordance with TestMethods C20, C 830,orC 914, especially recommended forfriable samples.7.2 Place the specimens in the chamber and seal thechamber. Bring the chamber to the specified test temperatureand then introduce steam at the presc
18、ribed rate (6.1).7.3 Upon completion of the 500-h period at the prescribedtemperature, shut off the steam supply and then the heat source.When specimens are cool, measure the weight and volumeusing the same method used for 7.1, and calculate the bulkdensity.8. Report8.1 The average percent volume ch
19、ange based on theoriginal volume is reported as the prime variable with weight,bulk density, and length changes included as supplementaryinformation. The percent volume change equals 100 times thedifference between the new and original volume all divided bythe original volume, orVolume Change, % 5Vn
20、2 Vo!Vo3 100where:Vn= new volume andVo= original volume.9. Precision and Bias9.1 Interlaboratory Test Data and AnalysisThree speci-mens each of five different materials were tested by fivelaboratories. The test data and analyses used in establishingthis precision statement are filed as a round robin
21、.3Thevariable measured is percent volume expansion, the testtemperature 1100C (2010F).9.2 PrecisionTwo averages of observed values should beconsidered significantly different at the 95 % probability levelif the difference equals or exceeds the critical differences listedin Table 1.9.3 BiasNo justifi
22、able statement on bias can be madesince the true or standard value of volume expansion for thesematerials cannot be established by an accepted referencemethod.10. Keywords10.1 oxidation; refractories; silicon carbideASTM International takes no position respecting the validity of any patent rights as
23、serted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time
24、by the responsible technical 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 International Headquarters. Your comments will rec
25、eive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM Int
26、ernational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or thro
27、ugh the ASTM website(www.astm.org).3Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: C08-1004.TABLE 1 Example of Critical Difference ValuesANumber of Ob-servations inEach AverageCritical Difference BetweenAverages, Units of MeasureSingle-OperatorBetween-LaboratoryFrit Bonded SiC 3 3.26 18.11Clay Bonded SiC 3 32.13 31.34Fines Bonded SiC 3 0.39 0.81Silicon OxynitrideBonded SiC 3 1.91 7.25Silicon NitrideBonded SiC 3 0.27 0.56AThis table is excerpted from RR: C08-1004, available from ASTM Headquar-ters.C 863 00 (2005)2
