ASTM F2094 F2094M-2018a Standard Specification for Silicon Nitride Bearing Balls.pdf

1、Designation: F2094/F2094M 18aStandard Specification forSilicon Nitride Bearing Balls1This standard is issued under the fixed designation F2094/F2094M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year of last revision. A num

2、ber in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers the establishment of the basicquality, physical/mechanical property, and test requirementsfor silicon nitride ba

3、lls Classes I, II, and III to be used for ballbearings and specialty ball applications.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independentl

4、y of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.3 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of Internationa

5、l Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 Order of Precedence:2.1.1 In the event of a conflict between the text of thisdocument and the references herein, the text of this documenttakes preced

6、ence. Nothing in this document, however, super-sedes applicable laws and regulations unless a specific exemp-tion has been obtained.2.2 ASTM Standards:2C1161 Test Method for Flexural Strength of AdvancedCeramics at Ambient TemperatureC1421 Test Methods for Determination of Fracture Tough-ness of Adv

7、anced Ceramics at Ambient Temperature2.3 ANSI Standard:ANSI/ASQC Z1.4 Sampling Procedures and Tables for In-spection by Attributes32.4 ABMA Standards:STD 10 Metal Balls42.5 ASME Standard:B 46.1 Surface Texture (Surface Roughness, Waviness, andLay)52.6 ISO Standards:64505 HardmetalsMetallographic Det

8、ermination of Poros-ity and Uncombined Carbon2.7 JIS Standards:R 1601 Testing Method for Flexural Strength (Modulus ofRupture) of High Performance Ceramics7R 1607 Testing Method for Fracture Toughness of HighPerformance Ceramics72.8 CEN Standards:EN 843-1 Advanced Technical CeramicsMonolithicCeramic

9、sMechanical Properties at Room Temperature,Part 1. Determination of Flexural Strength8ENV 843-5 Advanced Technical CeramicsMonolithicCeramicsMechanical Properties at Room Temperature,Part 5, Statistical Analysis83. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 ball diameter var

10、iation, Vdws, nball diameter varia-tion is the difference between the largest and smallest diametermeasured on the same ball.1This specification is under the jurisdiction ofASTM Committee F34 on RollingElement Bearings and is the direct responsibility of Subcommittee F34.01 onRolling Element.Current

11、 edition approved May 1, 2018. Published July 2018. Originally approvedin 2001. Last previous edition approved in 2018 as F2094/F2094M18. DOI:10.1520/F2094_F2094M-18A.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual

12、Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Application for copies should be addressed to theAmerican National StandardsInstitute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.4Application for copies should be

13、 addressed to the American Bearing Manufac-turers Association, 1200 19th Street NW, Suite 300, Washington, DC 20036-2401.5Application for copies should be addressed to the American Society ofMechanical Engineers (ASME), ASME International Headquarters, Three ParkAve., New York, NY 10016-5990, http:/

14、www.asme.org.6Application for copies should be addressed to the Available from InternationalOrganization for Standardization (ISO), ISO Central Secretariat, BIBC II, Cheminde Blandonnet 8, CP 401, 1214 Vernier, Geneva, Switzerland, http:/www.iso.org.7Application for copies should be addressed to the

15、 Japanese Standards Organi-zation (JSA), 4-1-24 Akasaka Minato-Ku, Tokyo, 107-8440, Japan, http:/www.jsa.or.jp.8Application for copies should be addressed to the British Standards Institute(BSI), 389 Chiswick High Rd., London W4 4AL, U.K., http:/www.bsi-.Copyright ASTM International, 100 Barr Harbor

16、 Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendation

17、s issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.1.2 ball gauge, S, nprescribed small amount by whichthe lot mean diameter should differ from nominal diameter, thisamount being one of an established series of amounts. A ballgauge, in combination with the ball g

18、rade and nominal balldiameter, should be considered as the most exact ball sizespecification to be used by a customer for ordering purposes.3.1.3 ball gauge deviation, S, ndifference between thelot mean diameter and the sum of the nominal diameter and theball gauge.3.1.4 ball grade, G, nspecific com

19、bination of dimensionalform and surface roughness tolerances. A ball grade is desig-nated by a grade number followed by the letter “C” indicatingSilicon Nitride Ceramic.3.1.5 blank lot, nsingle group of same-sized ball blanksprocessed together from one material lot through densification.3.1.6 cerami

20、c second phase, nsintering additive basedphases, for example, yttria and alumina, which appear darkeror lighter than the silicon nitride matrix, but are not highlyreflective in nature when viewed under reflected light micros-copy and bright field illumination.3.1.7 color variation, nan area that app

21、ears lighter ordarker than the surrounding area under reflected light micros-copy but with no discernible physical discontinuity associatedwith it.3.1.7.1 DiscussionColor variation is often not visibleunder scanning electron microscopy (SEM) examination.3.1.8 c-cracks, ncurved, constant radius crack

22、s, the resultof ball-to-ball impact during finishing or subsequent handling.In extreme cases, the cracks can form a complete circle andmultiple concentric cracks can form.3.1.9 cracks, nirregular, narrow breaks in the surface ofthe ball typically having a visible width of less than 0.002 mm0.00008 i

23、n.3.1.9.1 DiscussionMost cracks are formed after densifica-tion but occasionally may be present as material faults. Somecracks may not be visible with normal white light microscopyand may only show up under ultraviolet light after processingwith a suitable fluorescent penetrant.3.1.10 cuts, nMechani

24、cally induced random, short, lineardepressions in the surface.3.1.11 deviation from spherical form, Rw, ngreatestradial distance in any radial plane between a sphere circum-scribed around the ball surface and any point on the ballsurface.3.1.12 finish lot, nsingle group of same-sized balls (whichmay

25、 be derived from multiple blank lots of the same materiallot) processed together through finishing.3.1.13 inclusion, nany discrete imhomogeneity in themicrostructure that is not intended to be included in thematerial.3.1.13.1 DiscussionInclusions typically consist of foreignmaterial as a result of u

26、nintended external powder contamina-tion and resulting reaction product after sintering.3.1.14 lot diameter variation, Vdwl, ndifference betweenthe mean diameter of the largest ball and that of the smallestball in the lot.3.1.15 lot mean diameter, Dwml, narithmetic mean of themean diameter of the la

27、rgest ball and that of the smallest ballin the lot.3.1.16 material lot, nsingle process lot of a blendedpowder (blended with additives), produced from a single lot ofsilicon nitride or silicon metal raw powder received from amaterial supplier.3.1.16.1 DiscussionWhat constitutes a “single processlot”

28、 of blended powder can vary depending on the standardpractices of the vendor and the requirements of the customerand application. For example, for many customers/applications, combining multiple mill charges from one rawmaterial lot into a single material lot is acceptable while forothers, each mill

29、 charge would be considered a separatematerial lot. It is difficult, if not impossible, for a singledefinition of material lot to apply to all applications. Thematerial lot should be defined such that application-appropriatetraceability is maintained and adequate testing appropriate forthe intended

30、application is performed to ensure that thechemistry and material properties of densified parts meetspecifications. The material lot requirements should be dis-cussed and agreed between the vendor and customer.3.1.17 mean diameter of a ball, Dwm, narithmetic meanof the largest and the smallest actua

31、l single diameters of theball.3.1.18 metallic phase, nmaterial phase that is highlyreflective when viewed by reflected light microscopy andbright field illumination.3.1.19 metallic smears, nmetallic material from lappingor measuring equipment transferred onto the ball surface.3.1.20 nominal diameter

32、, Dw, nsize ordered that is thebasis to which the nominal diameter tolerances apply. Thenominal diameter is specified in inches or millimeters (decimalform).3.1.21 nominal diameter tolerance, nmaximum allowabledeviation from true specified nominal diameter for the indi-cated grade.3.1.22 pits, nvoid

33、s or cavities in the ball surface.3.1.22.1 DiscussionPits can be formed by severe materialpullout during ball finishing. Pits can also be a result ofbreakout of inclusions during finishing.3.1.23 porosity, nsmall, closely spaced voids permeating aregion of the ball surface or the whole ball.3.1.24 p

34、ressing defects, nthe result of cracks in the ballblanks prior to densification.3.1.24.1 DiscussionSome pressing defects heal more orless completely on densification resulting in a region ofmaterial with slightly different composition and optical char-acteristics than the rest of the ball. These are

35、 known as healedor partially healed pressing defects. Unhealed or open pressingdefects can have the appearance of cracks or fissures.3.1.25 raw material lot, nsingle process lot of raw siliconnitride or raw silicon metal powder received from a materialsupplier.F2094/F2094M 18a23.1.26 scratches, nnar

36、row, linear, shallow abrasions onthe surface.3.1.27 scuffs, na dense concentration of small, parallelsuperficial scratches.3.1.28 single diameter of a ball, Dws, nthe distancebetween two parallel planes tangent to the surface of the ball.3.1.29 snowflakes, nregions of microporosity in the grainbound

37、ary phase that often display a dendritic appearance.3.1.29.1 DiscussionSnowflakes show up as white den-dritic features when viewed with oblique illumination or withultraviolet light after processing with a fluorescent penetrant.The individual micropores are often submicron in size and thesnowflakes

38、can range in size from less than 10 m .00039 in.to over 1,000 m .039 in. in extreme cases.3.1.30 surface roughness Ra, nsurface irregularities withrelative small spacings, which usually include irregularitiesresulting from the method of manufacture being used or otherinfluences, or both.3.1.31 unit

39、container, ncontainer identified as containingballs from the same manufacture lot of the same composition,grade, and nominal diameter, and within the allowable diam-eter variation per unit container for the specified grade.4. Classification4.1 Silicon nitride materials for bearing and specialty ball

40、applications are specified according to the following materialclasses (see Appendix X1 for typical current applications):4.1.1 Class IHighest grade of material in terms of prop-erties and microstructure. Suitable for use in the most demand-ing applications. This group adds high reliability and durab

41、ilityfor extreme performance requirements.4.1.2 Class IIGeneral class of material for most bearingand specialty ball applications. This group addresses theconcerns of ball defects as is relative to fatigue life, levels oftorque, and noise.4.1.3 Class IIILower grade of material for low dutyapplicatio

42、ns only. This group of applications primarily takesadvantage of silicon nitride material properties. For example:Light weight, chemical inertness, lubricant life extension dueto dissimilarity with race materials, and so forth.5. Ordering Information5.1 Acquisition documents should specify the follow

43、ing:5.1.1 Title, number, and date of this specification.5.1.2 Class, grade, and size (see 4.1, 8.6, and 8.7).6. Material6.1 Unless otherwise specified, physical and mechanicalproperty requirements will apply to all material classes.6.2 To be classified as Class I, silicon nitride balls shall beprodu

44、ced from either silicon nitride powder having the com-positional limits listed in Table 1 or from silicon metal powder,which after nitridation complies with the compositional limitslisted in Table 1.6.3 Composition is measured in weight percent. Testingshall be carried out by a facility qualified an

45、d approved by thesupplier. Specific equipment, tests, and/or methods are subjectto agreement between suppliers and their customers.6.4 Compounds may be added to promote densification andenhance product performance and quality.6.5 Iron oxides may be added to promote densification withthe total iron c

46、ontent for the final product not to exceed 1.0weight %.6.6 Precautions should be taken to minimize contaminationby foreign materials during all stages of processing up to andincluding densification.6.7 A residual content of up to 2 % tungsten carbide frompowder processing is allowable.6.8 Final comp

47、osition shall meet and be reported accordingto the specification of the individual supplier.6.9 Notification will be made upon process changes.6.10 Specific requirements such as specific material gradedesignation, physical/mechanical property requirements (forexample, density) or quality or testing

48、requirements shall beestablished by specific application. The special requirementsshall be in addition to the general requirements established inthis specification.6.11 Typical mechanical properties will fall within the rangelisted in Table 2. Individual requirements may have tighterranges. The vend

49、or shall certify that the silicon nitride materialsupplied has physical and mechanical properties within therange given in Table 2. In the case of properties indicated by(+), the provision of the data is not mandatory.TABLE 1 Compositional Limits for Starting Silicon NitridePowders or Silicon Powder Converted to Silicon Nitride forClass I MaterialsAConstituents Limits (wt %)Silicon nitride 97.0 min.Free silicon 0.3 max.Carbon 0.3 maxIron 0.5 max.AOther impurities or elements such as sodium, potassium, chlorine, e