ASTM_D_3553_-_76_1996.pdf

Designation:D 3553 76(Reapproved 1996)Standard Test Method forFiber Content by Digestion of Reinforced Metal MatrixComposites1This standard is issued under the fixed designation D 3553;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(e)indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1.Scope1.1 This test method covers the digestion method for thedetermination of the fiber content of metal matrix composites.The test method used is based on the digestion of the matrixmetal by a suitable acid or base that does not attack the fibersexcessively(maximum 2%weight loss).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 to use.For specific safetyprecautions,see Section 7.2.Referenced Documents2.1 ASTM Standards:D 792 Test Methods for Density and Specific Gravity(Rela-tive Density)of Plastics by Displacement23.Summary of Test Method3.1 The test method consists of digesting the matrix metal ofa weighed composite specimen.The digestion medium useddepends upon the nature of the matrix and fiber.The residue isfiltered,washed,dried,and weighed.The weight percent offiber can then be converted to a volume percent if the fiber andcomposite densities are known.Acorrection for the weight lossof fiber,if any,may be made.3.2 Three procedures are given:Procedure A for metalsdigestible by nitric acid;Procedure B for metals digestible bysodium hydroxide;and Procedure C for metals digestible byhydrochloric acid.Examples of metals coming under Proce-dure A are copper and steel,under Procedure B are aluminum,and under Procedure C are magnesium,titanium,steel,andcopper.4.Significance and Use4.1 The fiber content of a composite must be determined tocalculate the apparent strength and modulus of the reinforcingfibers in the composite.Fiber content may be further used toevaluate the quality of a given composite specimen.5.Apparatus5.1 General:5.1.1 Sintered-Glass Filter,fritted,medium porosity.5.1.2 Crucible Holder.5.1.3 Analytical Balance.5.1.4 Drying Oven,capable of attaining 100C.5.1.5 Glass Vacuum Filter Flask.5.1.6 Vacuum Source,capable of 13.3 kPa(100 mm Hg)pressure.5.2 Procedure A:5.2.1 Flasks,with ground-glass joints.5.2.2 Water Reflux Condenser,with ground-glass joints.5.2.3 Water or Oil Bath,temperature-regulated.5.3 Procedures B and C:5.3.1 Calibrated Pipets.5.3.2 Hot Plate.6.Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.Unless otherwise indicated,it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.3Other grades may beused,provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.6.2 Procedure A:6.2.1 Nitric Acid,HNO365%aqueous.6.3 Procedure B:6.3.1 Sodium Hydroxide Solution,NaOH 40 to 80%aque-ous.6.4 Procedure C:6.4.1 Hydrochloric Acid,HCl 5 to 10%aqueous.1This test method is under the jurisdiction of ASTM Committee D-30 on HighModulus Fibers and Their Compositesand is the direct responsibility of Subcom-mittee D30.07on Metal-Matrix Composites.Current edition approved Dec.31,1976.Published March 1977.2Annual Book of ASTM Standards,Vol 08.01.3Reagent Chemicals,American Chemical Society Specifications,AmericanChemical Society,Washington,DC.For suggestions on the testing of reagents notlisted by the American Chemical Society,see Analar Standards for LaboratoryChemicals,BDH Ltd.,Poole,Dorset,U.K.,and the United States Pharmacopeiaand National Formulary,U.S.Pharmaceutical Convention,Inc.(USPC),Rockville,MD.1Copyright ASTM,100 Barr Harbor Drive,West Conshohocken,PA 19428-2959,United States.NOTICE:This standard has either been superseded and replaced by a new version or discontinued.Contact ASTM International(www.astm.org)for the latest information.7.Safety Precautions7.1 Use standard procedures for handling hot acid.48.Test Specimens8.1 Preferably five or more specimens,each weighing atleast 300 mg,are cut from the sample of interest.The specimenmay be of any convenient shape.9.Procedures9.1 Procedure ASteel or copper matrices(and others thatcan be digested by HNO3):9.1.1 Weigh each specimen on an analytical balance to foursignificant figures.9.1.2 If the fiber content by volume is required,determinethe density of each specimen by a liquid displacement tech-nique,in accordance with Test Methods D 792.9.1.3 Place each specimen in a separate flask containing 30mL of 65%HNO3.9.1.4 Fit the flasks