1、Designation: F 2094/F 2094M 08Standard Specification forSilicon Nitride Bearing Balls1This standard is issued under the fixed designation F 2094/F 2094M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision, the year of last revision. A
2、number in parentheses indicates the year of lastreapproval. 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
3、 balls 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 are not exact equivalents; therefore, each systemmust be used independently
4、 of the other. Combining valuesfrom the two systems may result in nonconformance with thespecification.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 thi
5、s document, however, super-sedes applicable laws and regulations unless a specific exemp-tion has been obtained.2.2 ASTM Standards:2C 1161 Test Method for Flexural Strength of AdvancedCeramics at Ambient TemperatureC 1421 Test Methods for Determination of Fracture Tough-ness of Advanced Ceramics at
6、Ambient 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-i
7、ty and 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 Properti
8、es at 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 di
9、ameter 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 wi
10、th the 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.1This specification is u
11、nder the jurisdiction ofASTM Committee F34 on RollingElement Bearings and is the direct responsibility of Subcommittee F34.01 onRolling Element.Current edition approved Nov. 15, 2008. Published January 2009. Originallyapproved in 2001. Last previous edition approved in 2006 as F 2094 061.2For refere
12、nced 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.3Application for copies should be addressed to theAmerican National Stan
13、dardsInstitute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.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 America
14、n Society ofMechanical Engineers (ASME), ASME International Headquarters, Three ParkAve., New York, NY 10016-5990, http:/www.asme.org6Application 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.7Appli
15、cation for copies should be addressed to the British Standards Institute(BSI), 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.3.1.4 ball grade (G)specific combination of dim
16、ensionalform 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 lotsingle group of same-sized ball blanksprocessed together from one material lot through densification.3.1.6 deviation from spherical
17、 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 together through finishing.
18、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 lotsingle process lot of si
19、licon 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 apply. Thenominal diamet
20、er 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 surface of the ball.3.1.15 s
21、urface 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 lot of the same composit
22、ion,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 Appendix X1 for typical cur
23、rent 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 material for most bearingand
24、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 material properties. F
25、or 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 (see 4.1, 8.6, and 8.7).6.
26、 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, which after nitridati
27、oncomplies 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 their customers.6.4 The f
28、ollowing compounds may be added to promotedensification and/or enhance product performance and quality.The following may be added as oxides, nitrides, oxynitrides, ormixtures:6.4.1 Aluminum,6.4.2 Magnesium,6.4.3 Barium,6.4.4 Lanthanum,6.4.5 Yttrium,6.4.6 Calcium, and6.4.7 Other rare earths.6.5 The f
29、ollowing may be added as nitrides, oxynitrides, orcarbonitrides:6.5.1 Titanium,6.5.2 Tantalum, and6.5.3 Zirconium.6.6 Aluminum silicon oxynitrides (aluminum nitride poly-types) may be added to promote densification.6.7 Iron oxides may be added to promote densification withthe total iron content for
30、the final product not to exceed 1.0weight %.6.8 Precautions should be taken to minimize contaminationby foreign materials during all stages of processing up to andincluding densification.6.9 A residual content of up to 2 % tungsten carbide frompowder processing is allowable.6.10 Final composition sh
31、all meet and be reported accord-ing to the specification of the individual supplier.6.11 Notification will be made upon process changes.6.12 Specific requirements such as specific material gradedesignation, physical/mechanical property requirements (forexample, density) or quality or testing require
32、ments shall beTABLE 1 Compositional Limits for Starting Silicon NitridePowders or Silicon Powder Converted to Silicon NitrideAConstituents 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, etc.indi
33、vidually shall not exceed 0.02 wt % max.F 2094/F 2094M 082established by specific application. The special requirementsshall be in addition to the general requirements established inthis specification.6.13 Typical mechanical properties will fall within the rangelisted in Table 2. Individual requirem
34、ents may have tighterranges. The vendor 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.7. Physical Properties7.1 The following physi
35、cal properties shall be measured, ata minimum, on each material lot.7.1.1 Average values for room temperature rupture strength(bend strength/modulus of rupture) for a minimum of 20individual determinations shall exceed the minimum valuesgiven in Table 3. Either 3-point or 4-point test methods may be
36、used for flexural strength, which should be measured inaccordance with Test Method C 1161 (size B), CEN 843-5, orJIS R 1601. Weibull modulus for each test series shall alsoexceed the minimum permitted values given in Table 3.Ifasample set of specimens for a material lot does not meet theWeibull modu
37、lus requirement in Table 3, then a second sampleset may be tested to establish conformance.7.1.2 The hardness (HV) 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 (se
38、eAnnexA1) or by a standardfracture toughness test method. Average values for hardnessand fracture resistance shall 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 ma
39、ximum valuesgiven in Table 5 for the specified material class.7.1.4 The number of ceramic metallic or mixed inclusionsobserved 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 variati
40、on from the mean value of a sample ofat least 10 pieces taken from a batch of components manufac-tured under the 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 s
41、pecified material class. Density variationtesting will apply to all lots of material for the initial 50 lots. Ifconsistent 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
42、 balls. As the spectrum ofapplications for silicon nitride balls is very broad, this is notTABLE 2 Typical Mechanical PropertiesAProperties Minimum MaximumDensity, g/cc lb/ft3 3.0 187 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
43、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 10101016+ Compressive strength, MPa ksi 3000 435ASpecial material data should be obtained from individual suppliers.TABLE 3 Minim
44、um Values for Mean Flexural Strength andWeibull ModulusMaterial ClassUnit I II IIITransverse-rupturestrengthA3 points3,40(s3,30)MPa 900 920 800 825 600 625Weibullmodulus12 9 7Transverse-rupturestrengthA4-points4,40(s4,30)MPa 765 805 660 705 485 530Weibullmodulus12 9 7AThe Flexural strength equivalen
45、ts 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 of size L.s4,40= 660 MPa means the four point flexure strength, on 40 mm spans is 660MPa as per Test Method C 1161 (size B)
46、 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 ClassProperty Unit Load I II IIIHardness HV5 5 kg 1500 1400 1350HV10 kg/mm210 kg 1480 1380 1325HV20 20 kg 1460 1360 1300Indenta
47、tion Fracture Resistance, IFR(or“TP”)(Annex A1)MPa=m 6.0 5.0 5.0Fracture Toughness, KIc(Test Methods C 1421 or JIS R 1607)MPa=m 6.0 5.0 5.0TABLE 5 Maximum Limits for Microstructural ConstituentsMaterial ClassI II IIIPorosity: Size(m) 10 10 25Volume Rating /ISO 4505 0.02 0.06 0.06Metallic Phases:Size
48、 (m) 10 10 25Ceramic 2ndPhases: Size (m) 25 25 25F 2094/F 2094M 083intended 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 specificrequirements for a given application.8.2 Unless
49、 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 is acceptable. Color variation within a singleball should be investigated
