ASTM C1212-1998(2010) Standard Practice for Fabricating Ceramic Reference Specimens Containing Seeded Voids《包含晶粒孔隙的陶瓷参考试样的制备》.pdf
《ASTM C1212-1998(2010) Standard Practice for Fabricating Ceramic Reference Specimens Containing Seeded Voids《包含晶粒孔隙的陶瓷参考试样的制备》.pdf》由会员分享,可在线阅读,更多相关《ASTM C1212-1998(2010) Standard Practice for Fabricating Ceramic Reference Specimens Containing Seeded Voids《包含晶粒孔隙的陶瓷参考试样的制备》.pdf(3页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: C1212 98 (Reapproved 2010)Standard Practice forFabricating Ceramic Reference Specimens ContainingSeeded Voids1This standard is issued under the fixed designation C1212; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he 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 This practice describes procedures for fabricating bothgreen and sintered test bars of silicon carbide and
3、siliconnitride containing both internal and surface voids at prescribedlocations.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated wit
4、h 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:2B311 Test Method for Density of Powder Metallurgy (PM)Materials Con
5、taining Less Than Two Percent PorosityC373 Test Method for Water Absorption, Bulk Density,Apparent Porosity, and Apparent Specific Gravity of FiredWhiteware Products3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 green specimena ceramic specimen formed as origi-nally compacted
6、 prior to high-temperature densification.3.1.2 internal voida cavity in a specimen with no connec-tion to the external surface.3.1.3 seeded voidsintentionally placed discontinuities atprescribed locations in reference specimens.3.1.4 sintered specimenformed ceramic specimen afterfiring to densify an
7、d remove solvents or binders.3.1.5 surface voida pit or cavity connected to the externalsurface of a specimen.4. Significance and Use4.1 This practice describes a method of fabricating knowndiscontinuities in a ceramic specimen. Such specimens areneeded and used in nondestructive examination to demo
8、nstratesensitivity and resolution and to assist in establishing properexamination parameters.5. Apparatus5.1 Aeroduster, moisture-free.5.2 Die, capable of exerting a pressure of up to 120 MPa,that will not contaminate the compacted material.5.3 Optical Magnifier, capable of providing 10 to 30Xmagnif
9、ication.5.4 Tubing, latex, thin-wall, capable of withstanding iso-press.5.5 Carver Press or similiar type of appartus capable ofexerting the necessary pressure to consolidate the sample.5.6 Cold Isostatic Press, capable of maintaining 500 MPa.5.7 Vacuum Oven or Furnace which can maintain a tem-perat
10、ure of 525C.5.8 Imaging Equipment with the capability of producing ahard copy output of the image (that is, 35mm camera, CCDcamera outputted to a video printer, a stereo microscope with 4X 5 instamatic film, etc.).5.9 Sintering Furnaces capable of reaching temperatures of14002200C. Depending on the
11、ceramic system chosen, thefurnace may be required to operate in a vacuum and/or underinert gas atmospheres at pressures as high as 200 MPa.5.10 Commercial or similar device capable of measuringwithin .01 mg. Measuring densities according to Archimedesprinciple requires the use of a sample holder sus
12、pended inwater attached to the scale.6. Materials6.1 Silicon Carbide or Silicon Nitride Powders, of appro-priate purity and particle size, prepared with sintering aids andbinder representative of the product to be inspected and in amanner appropriate for dry pressing with granule size less than100-m
13、esh.1This practice is under the jurisdiction of ASTM Committee C28 on AdvancedCeramics and is the direct responsibility of Subcommittee C28.03 on PhysicalProperties and Non-Destructive Evaluation.Current edition approved Dec. 1, 2010. Published January 2011. Originallyapproved in 1992. Last previous
14、 edition approved in 2004 as C121298 (2004).DOI: 10.1520/C1212-98R10.2For 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
15、website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.2 Styrene Divinyl Benzene Spheres, with diameters asnecessary. Other material with low vaporization temperaturesmay be substituted, but pressing characteristics and final void
16、sizes may be different.7. Fabrication of Surface Voids7.1 Green Specimens:7.1.1 The test piece geometry must be appropriate for thesize and geometry limits of the NDE test method. If thepurpose of the test is to determine if the NDE method issuitable for the detection of voids in a particular part/s
17、ample,ideally the test sample should be identitcal to the part/sample.If this is not feasible due to fabrication or testing limitations,the test sample should be similar to the part/sample in chemicalcomposition, density, and thickness (the thickness of the testsample should be the same as the thick
18、ness in the area of thepart/sample being examined.7.1.2 Procedure:7.1.2.1 Prepare the test specimen bars by pouring ceramicpowder into a die in an amount sufficient to make a specimenof the desired thickness. Level the surface and press at anominal pressure of 60 MPa.7.1.2.2 Remove the ram to expose
19、 the specimen. Clean thespecimen of all particles that are not flush with the top surface;this can generally be performed with a moisture-free aero-duster.7.1.2.3 Place large spheres in the desired location on thespecimen surface. Small microspheres may be moved to thedesired position with a single
20、human hair taped to a stiff plasticrod, using the assistance of an optical magnifier.7.1.2.4 Press the spheres into the surface at a suitablepressure to obtain the desired strength for handling of the greencompact (typically 120 MPa).7.1.2.5 Remove the bar from the die and clear the surfacesof extra
21、neous particles. An aeroduster or brush should beadequate.7.1.2.6 Place the specimen in a thin-wall latex tube andevacuate the air. Seal the tube end. Cold isopress at a pressuresuitable for a specific material (nominally 210420 MPa).7.1.2.7 Remove the specimen from the tubing and heat it ina vacuum
22、 to decompose the spheres (525C for 45 min forstyrene divinyl benzene).7.1.2.8 Mark the specimen orientation with a scribe mark orby beveling a corner or edge. Remove extraneous particlesfrom all surfaces with an aeroduster or brush. Light sandingmay be necessary, for adherent particles.7.1.3 Void M
23、easurementMeasure the lateral dimensionsin two orthogonal directions. The depth can be measured byfocusing a microscope alternately on the specimen surface andon the bottom of the crater and noting the difference in thevertical position of the tube. Use a magnification suitable formeasuring depth wi
24、thin 2 m.7.1.4 Measure the bulk density of the specimen from directvolume and weight measurements.7.2 Sintered Specimens:7.2.1 Procedure:7.2.1.1 Follow the steps given in 7.1.2 to produce greenspecimens.7.2.1.2 Sinter green samples under suitable conditions toachieve full densification. Nominal sint
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