ASTM_C_831_-_98_2013.pdf

Designation:C83198(Reapproved 2013)Standard Test Methods forResidual Carbon,Apparent Residual Carbon,and ApparentCarbon Yield in Coked Carbon-Containing Brick andShapes1This standard is issued under the fixed designation C831;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.1.Scope1.1 These test methods cover the determination of residualcarbon content in carbon-bearing brick and shapes after aprescribed coking treatment.They provide two procedures.The first procedure is based on the combustion of carbon andits measurement as carbon dioxide.However,when using thefirst procedure for articles that contain silicon carbide or othercarbides,no distinction will be made between carbon present inthe form of a carbide and carbon present as elemental carbon.The second procedure provides a method for calculatingapparent residual carbon(on the basis of weight loss afterigniting the coked specimens),apparent carbonaceous materialcontent,and apparent carbon yield.If the second procedure isused for brick or shapes that contain metallic additives orcarbides,it must be recognized that there will be a weight gainassociated with the oxidation of the metals,or carbides,orboth.Such a weight gain can change the results substantiallyand this must be kept in mind when interpreting the data.1.2 The values stated in inch-pound units are to be regardedas the standard.The values given in parentheses are forinformation only.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-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2C571 Methods for Chemical Analysis of Carbon andCarbon-Ceramic Refractories(Withdrawn 1995)3D2906 Practice for Statements on Precision and Bias forTextiles(Withdrawn 2008)3E11 Specification for Woven Wire Test Sieve Cloth and TestSieves3.Significance and Use3.1 These test methods are designed for use with carbon-containing products.The residual carbon content of a cokedcarbon containing brick or shape is an indication of how muchcarbon may be available,in service,to resist slag attack on,oroxidation loss of,that body.Apparent carbon yield gives anestimate of the relative efficiency of the total carbonaceousmatter to be retained as residual carbon.3.2 Residual carbon has a direct bearing on several proper-ties of a pitch or resin containing refractory such as ignitedporosity,density,strength,and thermal conductivity.3.3 Thesetestmethodsaresuitableforproductdevelopment,manufacturing control and specification accep-tance.3.4 These test methods are very sensitive to specimen size,coking rates,etc.;therefore,strict compliance with these testmethods is critical.3.5 Appreciable amounts of reducible components,such asFe2O3,will have a noticeable effect on the results.Thus,valuesobtained by these test methods will be different when brickremoved from service is tested.This must be kept in mindwhen attempting to use these test methods in an absolute sense.3.6 Oxidizable components such as metals and carbides canhave a noticeable effect on the results.This must be kept inmind when using the second procedure,which is based onmeasuring weight loss after igniting the coked specimens.3.7 Testing of brick or shapes that contain magnesium metalpresents special problems since this metal is highly volatile andsubstantial amounts of the magnesium can be lost from thesample during the coking procedure.This must be kept in mindwhen interpreting the results of testing of brick that contain1These test methods are under the jurisdiction of ASTM Committee C08 onRefractories and are the direct responsibility of Subcommittee C08.04 on ChemicalBehaviors.Current edition approved April 1,2013.Published August 2013.Originallyapproved in 1976.Last previous edition approved in 2008 as C831 98(2008).DOI:10.1520/C0831-98R13.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 magnesium.In addition,magnesium can react readily withatmospheric humidity.This must be kept in mind when storingbrick that contain magnesium.4.Apparatus4.1 For Coking:4.1.1 Gas or Electric Furnace with heating chamber ca-pable of receiving the coking box shown in Fig.1.NOTE1Samples should not be subjected to thermal gradients greaterthan 40F(22C)during he