1、Designation: F2094/F2094M 11Standard 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 numb
2、er 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 bal
3、ls 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 independently
4、 of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.2. Referenced Documents2.1 Order of Precedence:2.1.1 In the event of a conflict between the test of thisdocument and the references herein, the text of this documenttakes precedence. Nothing in this do
5、cument, 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 Advanced Ceramics at Ambien
6、t Temperature2.3 ANSI Standard:ANSI/ASQC Z1.4 Sampling Procedures and Tables forInspection 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:4505 HardmetalsMetallographic Determination of Poros-ity and
7、 Uncombined Carbon32.7 JIS Standards:R 1601 Testing Method for Flexural Strength (Modulus ofRupture) of High Performance Ceramics6R 1607 Testing Method for Fracture Toughness of HighPerformance Ceramics62.8 CEN Standards:EN 843-1 Advanced Technical CeramicsMonolithicCeramicsMechanical Properties at
8、Room Temperature,Part 1. Determination of Flexural Strength7ENV 843-5 Advanced Technical CeramicsMonolithicCeramicsMechanical Properties at Room Temperature,Part 5, Statistical Analysis73. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 ball diameter variation (Vdws)ball diameter
9、 varia-tion is the difference between the largest and smallest diametermeasured on the same ball.3.1.2 ball gage (S)prescribed small amount by which thelot mean diameter should differ from nominal diameter, thisamount being one of an established series of amounts. A ballgage, in combination with the
10、 ball grade 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 gage deviation (DS)difference between the lotmean diameter and the sum of the nominal diameter and theball gage.3.1.4 ball grade (G)specific c
11、ombination of dimensionalform and surface roughness tolerances. A ball grade is desig-nated by a grade number followed by the letter “C” indicatingSilicon Nitride Ceramic.1This specification is under the jurisdiction ofASTM Committee F34 on RollingElement Bearings and is the direct responsibility of
12、 Subcommittee F34.01 onRolling Element.Current edition approved May 1, 2011. Published May 2011. Originallyapproved in 2001. Last previous edition approved in 2008 as F2094/F2094M 08.DOI: 10.1520/F2094_F2094M-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Cus
13、tomer Service at serviceastm.org. For Annual 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:/w
14、ww.ansi.org4Application for copies should be 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, Thr
15、ee ParkAve., New York, NY 10016-5990, http:/www.asme.org.6Application for copies should be addressed to the Japanese Standards Organi-zation (JSA), 4-1-24 Akasaka Minato-Ku, Tokyo, 107-8440, Japan, http:/www.jsa.or.jp.7Application for copies should be addressed to the British Standards Institute(BSI
16、), 389 Chiswick High Rd., London W4 4AL, U.K., http:/www.bsi-.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.5 blank lotsingle group of same-sized ball blanksprocessed together from one material lot through densification.3.1.6 d
17、eviation from spherical form (DRw)greatest radialdistance in any radial plane between a sphere circumscribedaround the ball surface and any point on the ball surface.3.1.7 finish lotsingle group of same-sized balls (whichmay be derived from multiple blank lots of the same materiallot) processed toge
18、ther through finishing.3.1.8 lot diameter variation (Vdwl)difference between themean diameter of the largest ball and that of the smallest ballin the lot.3.1.9 lot mean diameter (Dwml)arithmetic mean of themean diameter of the largest ball and that of the smallest ballin the lot.3.1.10 material lots
19、ingle process lot of silicon nitride rawpowder received from a material supplier.3.1.11 mean diameter of a ball (Dwm)arithmetic mean ofthe largest and the smallest actual single diameters of the ball.3.1.12 nominal diameter (Dw)size ordered that is thebasis to which the nominal diameter tolerances a
20、pply. Thenominal diameter is specified in inches or millimeters (decimalform).3.1.13 nominal diameter tolerancemaximum allowabledeviation from true specified nominal diameter for the indi-cated grade.3.1.14 single diameter of a ball (Dws)the distance be-tween two parallel planes tangent to the surfa
21、ce of the ball.3.1.15 surface roughness (Ra)surface irregularities withrelative small spacings, which usually include irregularitiesresulting from the method of manufacture being used or otherinfluences, or both.3.1.16 unit containercontainer identified as containingballs from the same manufacture l
22、ot 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 ballapplications are specified according to the following materialclasses (see Appe
23、ndix 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 durabilityfor extreme performance requirements.4.1.2 Class IIGeneral class of materi
24、al 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 dutyapplications only. This group of applications primarily takesadvantage of silicon nitride
25、 material properties. For example:Light weight, chemical inertness, lubricant life extension dueto dissimilarity with race materials, etc.5. Ordering Information5.1 Acquisition documents should specify the following:5.1.1 Title, number, and date of this specification.5.1.2 Class, grade, and size (se
26、e 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 Silicon nitride balls should be produced from eithersilicon nitride powder having the compositional limits listed inTable 1 or from silicon metal powder
27、, which after nitridationcomplies with the compositional limits listed in Table 1.6.3 Composition is measured in weight percent. Testingshall be carried out by a facility qualified and approved by thesupplier. Specific equipment, tests, and/or methods are subjectto agreement between suppliers and th
28、eir 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 content for the final product not to exceed 1.0weight %.6.6 Precautions should be taken to minimize contaminationby fo
29、reign 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 composition shall meet and be reported accordingto the specification of the individual supplier.6.9 Notification will be
30、made upon process changes.6.10 Specific requirements such as specific material gradedesignation, physical/mechanical property requirements (forexample, density) or quality or testing requirements shall beestablished by specific application. The special requirementsshall be in addition to the general
31、 requirements established inthis specification.6.11 Typical mechanical properties will fall within the rangelisted in Table 2. Individual requirements may have tighterranges. The vendor shall certify that the silicon nitride materialsupplied has physical and mechanical properties within therange giv
32、en in Table 2. In the case of properties indicated by(+), the provision of the data is not mandatory.7. Physical Properties7.1 The following physical properties shall be measured, ata minimum, on each material lot.7.1.1 Average values for room temperature rupture strength(bend strength/modulus of ru
33、pture) for a minimum of 20individual determinations shall exceed the minimum valuesgiven in Table 3. Either 3-point or 4-point test methods may beused for flexural strength, which should be measured inaccordance with Test Method C1161 (size B), CEN 843-5, orJIS R 1601. Weibull modulus for each test
34、series shall alsoexceed the minimum permitted values given in Table 3.Ifasample set of specimens for a material lot does not meet theTABLE 1 Compositional Limits for Starting Silicon NitridePowders or Silicon Powder Converted to Silicon NitrideAConstituents Limits (wt %)Silicon nitride 97.0 min.Free
35、 silicon 0.3 max.Carbon 0.3 maxIron 0.5 max.AOther impurities or elements such as sodium, potassium, chlorine, etc.individually shall not exceed 0.02 wt % max.F2094/F2094M 112Weibull modulus requirement in Table 3, then a second sampleset may be tested to establish conformance.7.1.2 The hardness (HV
36、) shall be determined by the Vickersmethod (see Annex A1) using a load of at least 5 kg but notexceeding 20 kg. Fracture resistance shall be measured byeither an indentation technique (seeAnnexA1) or by a standardfracture toughness test method. Average values for hardnessand fracture resistance shal
37、l exceed the minimum of values forthe specified material class given in Table 4.7.1.3 Microstructure constituents visible at magnification inthe range 3100 to 3200 shall not exceed the maximum valuesgiven in Table 5 for the specified material class.7.1.4 The number of ceramic metallic or mixed inclu
38、sionsobserved in transverse sections shall not exceed the limitsgiven in Table 6.7.1.5 Macrostructure variation visible at 13 on a polishedsection is not permissible.7.1.6 Density variation from the mean value of a sample ofat least 10 pieces taken from a batch of components manufac-tured under the
39、same conditions shall not exceed the values for3 times the standard deviation (3 3 sigma) given in Table 7,according to the volume of the component after any finishingoperations and the specified material class. Density variationtesting will apply to all lots of material for the initial 50 lots. Ifc
40、onsistent results are achieved, the testing will be optional.8. Inspection and Verification8.1 The intent of this section is to list potential defects andmethods of inspection of finished balls. As the spectrum ofTABLE 2 Typical Mechanical PropertiesAProperties Minimum MaximumDensity, g/cc lb/ft3 3.
41、0 187 3.4 212Elastic modulus, GPa ksi 270 39 150 330 47 850Poissons ratio 0.23 0.29Thermal conductivity, W/m-K Btu/h-ft-F 20C (room temp.)20 11.5 38 21.9Specific heat, J/kg-K Btu/Ibm-F 650 0.167 800 0.191Coefficient of thermal expansion, 310-6/C(room temp. to 500C)2.3 3.4+ Resistivity, Ohm-m 1010101
42、6+ Compressive strength, MPa ksi 3000 435ASpecial material data should be obtained from individual suppliers.TABLE 3 Minimum Values for Mean Flexural Strength andWeibull ModulusMaterial ClassUnit I II IIITransverse-rupturestrengthA3 points3,40(s3,30)MPa 900 920 800 825 600 625Weibullmodulus12 9 7Tra
43、nsverse-rupturestrengthA4-points4,40(s4,30)MPa 765 805 660 705 485 530Weibullmodulus12 9 7AThe Flexural strength equivalents are based on Weibull volume or surfacescaling using the value of m for each cell and are rounded to the nearest 5 MPa.sn,L= denotes the flexure strength, n=3or4point,onspans o
44、f size L.s4,40= 660 MPa means the four point flexure strength, on 40 mm spans is 660MPa as per Test Method C1161 (size B) and CEN EN 843-1.s4,30= 705 MPa means the four point flexure strength, on 30 mm spans is 705MPa as per JIS R 1601.TABLE 4 Minimum Values for Hardness and ToughnessMaterial ClassP
45、roperty Unit Load I II IIIHardness HV5 5 kg 1500 1400 1350HV10 kg/mm210 kg 1480 1380 1325HV20 20 kg 1460 1360 1300Indentation Fracture Resistance, IFR(or“TP”)(Annex A1)MPa=m 6.0 5.0 5.0Fracture Toughness, KIc(Test Methods C1421 or JIS R 1607)MPa=m 6.0 5.0 5.0TABLE 5 Maximum Limits for Microstructura
46、l ConstituentsMaterial ClassI II IIIPorosity: Size(m) 10 10 25Volume Rating /ISO 4505 0.02 0.06 0.06Metallic Phases:Size (m) 10 10 25Ceramic 2ndPhases: Size (m) 25 25 25TABLE 6 Maximum Number of Inclusions per cm2of TransverseSectionMaterial ClassMaximum Extent inmI II III200 0 0 1100 to 200 0 1 250
47、 to 100 1 2 425 to 50 4 8 16TABLE 7 Maximum Allowable Density Variation (3 3 Sigma)Within a Single LotDensity Variation (g/cm3)Ball Diameter inInches mmMaterial ClassI II III332 to 1564 2.38to 5.95 0.010 0.015 0.0201564 to 1332 5.95to 10.32 0.008 0.010 0.0151332 to 58 10.32to 15.88 0.005 0.008 0.012
48、58 to 1516 15.88 to33.34 0.005 0.005 0.010F2094/F2094M 113applications for silicon nitride balls is very broad, this is notintended to define requirements, but to highlight these points.The type of defects, methods of inspection, and limits shouldbe agreed upon by the customer and vendor to meet the
49、 specificrequirements for a given application.8.2 Unless otherwise specified, all dimensional and forminspections shall be performed under the following conditions:8.2.1 TemperatureRoom ambient 20 to 25C 68 to77F.8.2.2 Humidity50 % relative, maximum.8.3 Unless otherwise required, product shall be capable ofpassing acceptance inspection in accordance withANSI/ASQCZ1.4 as specified in Table 8.8.4 Certain manufacturer to manufacturer or lot to lotvariation in color
