1、Designation: F2094/F2094M 13F2094/F2094M 14Standard 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 r
2、evision. A number 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 basic quality, physical/mechanical property, and test requirements forsil
3、icon nitride balls Classes I, II, and III to be used for ball bearings and specialty ball applications.1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may not be exact equivalents; therefore, each system shall be
4、 used independently of the other. Combining values from thetwo systems may result in non-conformance with the standard.2. Referenced Documents2.1 Order of Precedence:2.1.1 In the event of a conflict between the text of this document and the references herein, the text of this document takesprecedenc
5、e. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has beenobtained.2.2 ASTM Standards:2C1161 Test Method for Flexural Strength of Advanced Ceramics at Ambient TemperatureC1421 Test Methods for Determination of Fracture Toughness of Advanced
6、Ceramics at Ambient Temperature2.3 ANSI Standard:ANSI/ASQC Z1.4 Sampling Procedures and Tables for Inspection by Attributes32.4 ABMA Standards:STD 10 Metal Balls42.5 ASME Standard:B 46.1 Surface Texture (Surface Roughness, Waviness, and Lay)52.6 ISO Standards:4505 HardmetalsMetallographic Determinat
7、ion of Porosity and Uncombined Carbon32.7 JIS Standards:R 1601 Testing Method for Flexural Strength (Modulus of Rupture) of High Performance Ceramics6R 1607 Testing Method for Fracture Toughness of High Performance Ceramics62.8 CEN Standards:EN 843-1 Advanced Technical CeramicsMonolithic CeramicsMec
8、hanical Properties at Room Temperature, Part 1.Determination of Flexural Strength7ENV 843-5 Advanced Technical CeramicsMonolithic CeramicsMechanical Properties at Room Temperature, Part 5,Statistical Analysis71 This specification is under the jurisdiction of ASTM Committee F34 on Rolling Element Bea
9、rings and is the direct responsibility of Subcommittee F34.01 on RollingElement.Current edition approved Oct. 1, 2013March 15, 2014. Published October 2013March 2014. Originally approved in 2001. Last previous edition approved in 20112013as F2094/F2094M11.13. DOI: 10.1520/F2094_F2094M-11.10.1520/F20
10、94_F2094M-14.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Application for copies should be addressed to
11、the American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.4 Application for copies should be addressed to the American Bearing Manufacturers Association, 1200 19th Street NW, Suite 300, Washington, DC 20036-2401.5 Application for copies shoul
12、d be addressed to the American Society of Mechanical Engineers (ASME), ASME International Headquarters, Three Park Ave., New York,NY 10016-5990, http:/www.asme.org.6 Application for copies should be addressed to the Japanese Standards Organization (JSA), 4-1-24 Akasaka Minato-Ku, Tokyo, 107-8440, Ja
13、pan, http:/www.jsa.or.jp.7 Application for copies should be addressed to the British Standards Institute (BSI), 389 Chiswick High Rd., London W4 4AL, U.K., http:/www.bsi-.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes
14、have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official
15、document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 ball diameter variation, Vdws, nball diameter variation is the difference between the largest and smallest
16、 diametermeasured on the same ball.3.1.2 ball gage, S, nprescribed small amount by which the lot mean diameter should differ from nominal diameter, thisamount being one of an established series of amounts. A ball gage, in combination with the ball grade and nominal ball diameter,should be considered
17、 as the most exact ball size specification to be used by a customer for ordering purposes.3.1.3 ball gage deviation, S, ndifference between the lot mean diameter and the sum of the nominal diameter and the ballgage.3.1.4 ball grade, G, nspecific combination of dimensional form and surface roughness
18、tolerances. A ball grade is designatedby a grade number followed by the letter “C” indicating Silicon Nitride Ceramic.3.1.5 blank lot, nsingle group of same-sized ball blanks processed together from one material lot through densification.3.1.6 ceramic second phase, nsintering additive based phases,
19、for example, yttria and alumina, which appear darker or lighterthan the silicon nitride matrix, but are not highly reflective in nature.nature when viewed under reflected light microscopy andbright field illumination.3.1.7 color variation, nan area that appears lighter or darker than the surrounding
20、 area under reflected light microscopy butwith no discernible physical discontinuity associated with it.3.1.7.1 DiscussionColor variation is often not visible under scanning electron microscopy (SEM) examination.3.1.8 c-cracks, ncurved, constant radius cracks, the result of ball-to-ball impact durin
21、g finishing or subsequent handling. Inextreme cases, the cracks can form a complete circle and multiple concentric cracks can form.3.1.9 cracks, nirregular, narrow breaks in the surface of the ball typically having a visible width of less than 0.002mm0.00008 in.3.1.9.1 DiscussionMost cracks are form
22、ed after densification but occasionally may be present as material faults. Some cracks may not be visible withnormal white light microscopy and may only show up under ultraviolet light after processing with a suitable fluorescent penetrant.3.1.10 cuts, nMechanically induced random, short, linear dep
23、ressions in the surface.3.1.11 deviation from spherical form, Rw, ngreatest radial distance in any radial plane between a sphere circumscribedaround the ball surface and any point on the ball surface.3.1.12 finish lot, nsingle group of same-sized balls (which may be derived from multiple blank lots
24、of the same material lot)processed together through finishing.3.1.13 inclusion, nany discrete imhomogeneity in the microstructure that is not intended to be included in the material.3.1.13.1 DiscussionInclusions typically consist of foreign material as a result of unintended external powder contamin
25、ation and resulting reactionproduct after sintering.3.1.14 lot diameter variation, Vdwl, ndifference between the mean diameter of the largest ball and that of the smallest ballin the lot.3.1.15 lot mean diameter, Dwml, narithmetic mean of the mean diameter of the largest ball and that of the smalles
26、t ball inthe lot.3.1.16 material lot, nsingle process lot of silicon nitride a blended powder (blended with additives), produced from a singlelot of silicon nitride or silicon metal raw powder received from a material supplier.3.1.16.1 DiscussionWhat constitutes a “single process lot” of blended pow
27、der can vary depending on the standard practices of the vendor and therequirements of the customer and application. For example, for many customers/applications, combining multiple mill chargesfrom one raw material lot into a single material lot is acceptable while for others, each mill charge would
28、 be considered a separateF2094/F2094M 142material lot. It is difficult, if not impossible, for a single definition of material lot to apply to all applications.The material lot shouldbe defined such that application-appropriate traceability is maintained and adequate testing appropriate for the inte
29、nded applicationis performed to ensure that the chemistry and material properties of densified parts meet specifications. The material lotrequirements should be discussed and agreed between the vendor and customer.3.1.17 mean diameter of a ball, Dwm, narithmetic mean of the largest and the smallest
30、actual single diameters of the ball.3.1.18 metallic phase, nmaterial phase that is highly reflective when viewed by reflected light microscopy and bright fieldillumination.3.1.19 metallic smears, nmetallic material from lapping or measuring equipment transferred onto the ball surface.3.1.20 nominal
31、diameter, Dw, nsize ordered that is the basis to which the nominal diameter tolerances apply. The nominaldiameter is specified in inches or millimeters (decimal form).3.1.21 nominal diameter tolerance, nmaximum allowable deviation from true specified nominal diameter for the indicatedgrade.3.1.22 pi
32、ts, nvoids or cavities in the ball surface.3.1.22.1 DiscussionPits can be formed by severe material pullout during ball finishing. Pits can also be a result of breakout of inclusions duringfinishing.3.1.23 porosity, nsmall, closely spaced voids permeating a region of the ball surface or the whole ba
33、ll.3.1.24 pressing defects, nthe result of cracks in the ball blanks prior to densification.3.1.24.1 DiscussionSome pressing defects heal more or less completely on densification resulting in a region of material with slightly differentcomposition and optical characteristics than the rest of the bal
34、l. These are known as healed or partially healed pressing defects.Unhealed or open pressing defects can have the appearance of cracks or fissures.3.1.25 raw material lot, nsingle process lot of raw silicon nitride or raw silicon metal powder received from a materialsupplier.3.1.26 scratches, nnarrow
35、, linear, shallow abrasions on the surface.3.1.27 scuffs, na dense concentration of small, parallel superficial scratches.3.1.28 single diameter of a ball, Dws, nthe distance between two parallel planes tangent to the surface of the ball.3.1.29 snowflakes, nregions of microporosity in the grain boun
36、dary phase that often display a dendritic appearance.3.1.29.1 DiscussionSnowflakes show up as white dendritic features when viewed with oblique illumination or with ultraviolet light after processingwith a fluorescent penetrant. The individual micropores are often submicron in size and the snowflake
37、s can range in size from lessthan 10 m .00039 in. to over 1,000 m .039 in. in extreme cases.3.1.30 surface roughness Ra, nsurface irregularities with relative small spacings, which usually include irregularities resultingfrom the method of manufacture being used or other influences, or both.3.1.31 u
38、nit container, ncontainer identified as containing balls from the same manufacture lot of the same composition, grade,and nominal diameter, and within the allowable diameter variation per unit container for the specified grade.4. Classification4.1 Silicon nitride materials for bearing and specialty
39、ball applications are specified according to the following material classes(see Appendix X1 for typical current applications):4.1.1 Class IHighest grade of material in terms of properties and microstructure. Suitable for use in the most demandingapplications. This group adds high reliability and dur
40、ability for extreme performance requirements.4.1.2 Class IIGeneral class of material for most bearing and specialty ball applications. This group addresses the concerns ofball defects as is relative to fatigue life, levels of torque, and noise.4.1.3 Class IIILower grade of material for low duty appl
41、ications only. This group of applications primarily takes advantageof silicon nitride material properties. For example: Light weight, chemical inertness, lubricant life extension due to dissimilaritywith race materials, and so forth.F2094/F2094M 1435. Ordering Information5.1 Acquisition documents sh
42、ould 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. Material6.1 Unless otherwise specified, physical and mechanical property requirements will apply to all material classes.6.2 Silicon nitride balls shouldTo be classi
43、fied as Class I, silicon nitride balls shall be produced from either silicon nitridepowder having the compositional limits listed in Table 1 or from silicon metal powder, which after nitridation complies with thecompositional limits listed in Table 1.6.3 Composition is measured in weight percent. Te
44、sting shall be carried out by a facility qualified and approved by the supplier.Specific equipment, tests, and/or methods are subject to agreement between suppliers and their customers.6.4 Compounds may be added to promote densification and enhance product performance and quality.6.5 Iron oxides may
45、 be added to promote densification with the total iron content for the final product not to exceed 1.0 weight%.6.6 Precautions should be taken to minimize contamination by foreign materials during all stages of processing up to andincluding densification.6.7 A residual content of up to 2 % tungsten
46、carbide from powder processing is allowable.6.8 Final composition shall meet and be reported according to the specification of the individual supplier.6.9 Notification will be made upon process changes.6.10 Specific requirements such as specific material grade designation, physical/mechanical proper
47、ty requirements (forexample, density) or quality or testing requirements shall be established by specific application. The special requirements shall bein addition to the general requirements established in this specification.6.11 Typical mechanical properties will fall within the range listed in Ta
48、ble 2. Individual requirements may have tighter ranges.The vendor shall certify that the silicon nitride material supplied has physical and mechanical properties within the range givenin Table 2. In the case of properties indicated by (+), the provision of the data is not mandatory.7. Physical Prope
49、rties7.1 The following physical properties shall be measured, at a minimum, on each material lot.7.1.1 Average values for room temperature rupture strength (bend strength/modulus of rupture) for a minimum of 20 individualdeterminations shall exceed the minimum values given in Table 3. Either 3-point or 4-point test methods may be used for flexuralstrength, which should be measured in accordance with Test Method C1161 (size B), CEN 843-5, or JIS R 1601. Weibull modulusfor each test series shall also exceed the
