1、Designation: D7690 11Standard Practice forMicroscopic Characterization of Particles from In-ServiceLubricants by Analytical Ferrography1This standard is issued under the fixed designation D7690; the number immediately following the designation indicates the year oforiginal adoption or, in the case o
2、f revision, the 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 covers the identification by optical micros-copy of wear and contaminant particl
3、es commonly found inused lubricant and hydraulic oil samples that have beendeposited on ferrograms. This practice relates to the identifi-cation of particles, but not to methods of determining particleconcentration.1.2 This practice interfaces with but generally excludesparticles generated in the ab
4、sence of lubrication, such as maybe generated by erosion, impaction, gouging, or polishing.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, asso
5、ciated with 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:2D4057 Practice for Manual Sampling of Petroleum andPetrol
6、eum ProductsD4175 Terminology Relating to Petroleum, PetroleumProducts, and LubricantsD7684 Guide for Microscopic Characterization of Particlesfrom In-Service LubricantsG40 Terminology Relating to Wear and Erosion3. Terminology3.1 Definitions:3.1.1 abrasion, nwear by displacement of material causedb
7、y hard particles or hard protuberances. D41753.1.2 abrasive wear, nwear due to hard particles or hardprotuberances forced against and moving along a solid surface.G403.1.3 adhesive wear, nwear due to localized bondingbetween contacting solid surfaces leading to material transferbetween the two surfa
8、ces or loss from either surface. G403.1.4 break-in, nSee run-in. D4175, G403.1.5 break in, vSee run in. G403.1.6 catastrophic wear, nrapidly occurring or accelerat-ing surface damage, deterioration, or change of shape causedby wear to such a degree that the service life of a part isappreciably short
9、ened or its function is destroyed. G403.1.7 corrosion, nchemical or electrochemical reactionbetween a material, usually a metal surface, and its environ-ment that can produce a deterioration of the material and itsproperties. D41753.1.8 corrosive wear, nwear in which chemical or elec-trochemical rea
10、ction with the environment is significant. G403.1.9 debris, nin tribology, particles that have becomedetached in a wear or erosion process. G403.1.10 debris, nin internal combustion engines,solid con-taminant materials unintentionally introduced in to the engineor resulting from wear. D41753.1.11 fa
11、tigue wear, nwear of a solid surface caused byfracture arising from material fatigue. G403.1.12 fretting, nin tribology, small amplitude oscillatorymotion, usually tangential, between two solid surfaces incontact.3.1.12.1 DiscussionHere the term fretting refers only tothe nature of the motion withou
12、t reference to the wear,corrosion, or other damage that may ensue. The term fretting isoften used to denote fretting corrosion and other forms offretting wear. Usage in this sense is discouraged due to theambiguity that may arise. G401This practice is under the jurisdiction of ASTM Committee D02 on
13、PetroleumProducts and Lubricants and is the direct responsibility of Subcommittee D02.96.06on Practices and Techniques for Prediction and Determination of Microscopic Wearand Wear-related Properties.Current edition approved Jan. 1, 2011. Published March 2011. DOI: 10.1520/D769011.2For referenced AST
14、M 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshoho
15、cken, PA 19428-2959, United States.3.1.13 fretting wear, nwear arising as a result of fretting.(See fretting.) G403.1.14 friction, nresistance to sliding exhibited by twosurfaces in contact with each other. Basically there are twofrictional properties exhibited by any surface; static frictionand kin
16、etic friction. D41753.1.15 impact wear, nwear due to collisions between twosolid bodies where some component of the motion is perpen-dicular to the tangential plane of contact. G403.1.16 lubricant, nany material interposed between twosurfaces that reduces the friction or wear between them.D41753.1.1
17、7 lubricating oil, nliquid lubricant, usually compris-ing several ingredients, including a major portion of base oiland minor portions of various additives. D41753.1.18 pitting, nin tribology, form of wear characterizedby the presence of surface cavities the formation of which isattributed to proces
18、ses such as fatigue, local adhesion, orcavitation. G403.1.19 rolling, vin tribology, motion in a direction parallelto the plane of a revolute body (ball, cylinder, wheel, and soforth) on a surface without relative slip between the surfaces inall or part of the contact area. G403.1.20 rolling contact
19、 fatigue, ndamage process in atriboelement subjected to repeated rolling contact loads, in-volving the initiation and propagation of fatigue cracks in orunder the contact surface, eventually culminating in surfacepits or spalls. G403.1.21 run-in, nin tribology, initial transition processoccurring in
20、 newly established wearing contacts, often accom-panied by transients in coefficient of friction, or wear rate, orboth, which are uncharacteristic of the given tribologicalsystems long term behavior. (Synonym: break-in, wear-in.)D4175, G403.1.22 run in, vin tribology, to apply a specified set ofinit
21、ial operating conditions to a tribological system to improveits long term frictional or wear behavior, or both. (Synonym:break in,v,andwear in, v.) See also run-in,n) G403.1.23 rust, nof ferrous alloys, a corrosion product con-sisting primarily of hydrated iron oxides. D41753.1.24 scoring, nin tribo
22、logy, severe form of wear char-acterized by the formation of extensive grooves and scratchesin the direction of sliding. D4175, G403.1.25 sliding wear, nwear due to the relative motion inthe tangential plane of contact between two solid bodies.G403.1.26 soot, nin internal combustion, engines, sub-mi
23、cronsize particles, primarily carbon, created in the combustionchamber as products of incomplete combustion. D41753.1.27 spalling, nin tribology, the separation of macro-scopic particles from a surface in the form of flakes or chips,usually associated with rolling element bearings and gear teeth,but
24、 also resulting from impact events. G403.1.28 three-body abrasive wear, nform of abrasive wearin which wear is produced by loose particles introduced orgenerated between the contacting surfaces.3.1.28.1 DiscussionIn tribology, loose particles are con-sidered to be a “third body.” G403.1.29 triboelem
25、ent, none of two or more solid bodiesthat comprise a sliding, rolling, or abrasive contact, or a bodysubjected to impingement or cavitation. (Each triboelementcontains one or more tribosurfaces.)3.1.29.1 DiscussionContacting triboelements may be indirect contact or may be separated by an intervening
26、 lubricant,oxide, or other film that affects tribological interactions be-tween them. G403.1.30 two-body abrasive wear, nform of abrasive wearin which the hard particles or protuberances which produce thewear of one body are fixed on the surface of the opposing body.G403.1.31 viscosity, nratio betwe
27、en the applied shear stressand rate of shear. It is sometimes called the coefficient ofdynamic viscosity. This value is thus a measure of theresistance to flow of the liquid. The SI unit of viscosity is thepascal second (Pa.s). The centipoise (cP) is one millipascalsecond (mPa.s) and is often used.
28、D41753.1.32 wear, ndamage to a solid surface, usually involv-ing progressive loss or displacement of material, due to relativemotion between that surface and a contacting substance orsubstances. G40, D41753.2 Definitions of Terms Specific to This Standard:3.2.1 abrasive wear particles, nlong wire-li
29、ke particles inthe form of loops or spirals generated due to hard, abrasiveparticles present between wearing surfaces of unequal hard-ness.3.2.1.1 DiscussionSometimes called cutting wear par-ticles.3.2.2 analytical ferrography, ntechnique whereby par-ticles from an oil sample deposited by a ferrogra
30、ph areidentified to aid in establishing wear mode inside an oil-wettedpath of a machine.3.2.3 bichromatic microscope, noptical microscopeequipped with illumination sources both above and below themicroscope stage such that objects may be viewed either withreflected light, or with transmitted light,
31、or with both simulta-neously.3.2.4 black oxides of iron, ngenerally small, black clus-ters with pebbled surfaces showing small dots of blue andorange color. These are nonstoichiometric compounds contain-ing a mixture of Fe3O4,Fe2O3and FeO.3.2.5 contaminant particles, nparticles introduced froman ext
32、raneous source into the lubricant of a machine or engine.3.2.6 chunks, nfree metal particles 5 m with a shapefactor (major dimension to thickness ratio) of 15m, and with major dimension-to-thickness ratios between 5:1and 30:1.3.2.26 spheres, nmetal spheres may be the result ofincipient rolling conta
33、ct fatigue or they may be contaminantparticles from welding, grinding, coal burning and steel manu-facturing. Spheres may also be caused by electro-pitting.3.2.27 wear particles, nparticles generated from a wear-ing surface of a machine.4. Summary of Practice4.1 Periodic in-service lubricant samples
34、 are collected froma machine or engine as part of a routine condition monitoringprogram. A ferrogram is prepared from the sample to separateparticles from sample fluid. The ferrogram is subsequentlyexamined using an optical microscope to identify the types ofparticles present to aid in identifying t
35、he wear mode occurringin the oil-wetted path of the machine.4.2 In usual practice of a routine condition monitoringprogram, a ferrogram is not prepared for every sample taken,but may be prepared when routine tests such as spectrochemi-cal analysis, particle counting or ferrous debris monitoringindic
36、ate abnormal results.4.3 The user of this practice employs consistent terminologyto achieve accepted and understandable interpretations whencommunicating instructions and findings based on ferrographicanalysis.5. Significance and Use5.1 The objective of ferrography is to diagnose the opera-tional co
37、ndition of the machine sampled based on the quantityand type of particles observed in the oil. After break-in,normally running machines exhibit consistent particle concen-tration and particle types from sample to sample. An increasein particle concentration, accompanied by an increase in sizeand sev
38、erity of particle types is indicative of initiation of afault. This practice describes commonly found particles inin-service lubricants, but does not address methodology forquantification of particle concentration.5.2 This practice is provided to promote improved andexpanded use of ferrographic anal
39、ysis with in-service lubricantanalysis. It helps overcome some perceived complexity andresulting intimidation that effectively limits ferrographic analy-sis to the hands of a specialized and very limited number ofpractitioners. Standardized terminology and common reportingformats provide consistent
40、interpretation and general under-standing.5.3 Without particulate debris analysis, in-service lubricantanalysis results often fall short of concluding likely root causeor potential severity from analytical results because of missinginformation about the possible identification or extent ofdamaging m
41、echanisms.5.4 Ferrographic analysis, as described in this practice,provides additional particle identification capabilities beyondmethods described in Guide D7684 for the following reasons:(1) The ferrographic particle separation method is magneticthus making it possible to readily distinguish betwe
42、en ferrousand nonferrous wear particles.(2) Ferrography separates ferrous (magnetic) particles bysize.(3) Deposition is on a glass substrate so that particles maybe examined using transmitted light as well as reflected lightallowing particle types to be identified that cannot be identifiedwhen exami
43、nation is done using only reflected light.(4) Ferrograms may be heat treated providing importantdistinctions between ferrous alloy types (steel versus cast iron),D7690 113further distinctions among various nonferrous alloys and dis-tinctions between inorganic and organic particles.5.5 Caution must b
44、e exercised when drawing conclusionsfrom the particles found in a particular sample, especially if thesample being examined is the first from that type of machine.Some machines, during normal operation, generate wear par-ticles that would be considered highly abnormal in othermachines. For example,
45、many gear boxes generate severe wearparticles throughout their expected service life, whereas just afew severe wear particles from an aircraft gas turbine oilsample may be highly abnormal. Sound diagnostics requirethat a baseline, or typical wear particle signature, be estab-lished for each machine
46、type under surveillance.6. Apparatus6.1 Required Components:6.1.1 Ferrograph or Ferrogram MakerApparatus formagnetically separating particles from fluids.6.1.2 Bichromatic MicroscopeAn optical microscope isrequired with dry metallurgical objective lenses and equippedwith a reflected light source and
47、 a transmitted light source sothat objects may be viewed from both above and below themicroscope stage. This permits objects to be viewed either withreflected light, or with transmitted light, or with both simulta-neously. Bichromatic microscopes for ferrogram examinationare required to be equipped
48、with three objective lenses to givevarying degrees of magnification. The low magnificationobjective lens is typically 103, the medium magnificationobjective lens may be 403 or 503 and the high magnificationobjective lens may be 803 or 1003. Ten power (103) ocular(eyepiece) lenses are used such that
49、total magnificationachieved is 1003 at low magnification, 4003 or 5003 atmedium magnification and 8003 or 10003 at high magnifi-cation. The numerical apertures of the objective lenses need tobe high to maximize illumination of particle surfaces whenviewed in reflected light. It is required to be able to polarizeeither light path to facilitate particle identification. Polarizedlight aids in the identification of nonmetallic particles. A redfilter is required to be optionally placed in the reflected lightpath and a green filter is requir
