1、Designation: D7690 11 (Reapproved 2017)Standard 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
2、 or, in the case of 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 c
3、ontaminant particles 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 g
4、enerated in the absence 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 conc
5、erns, if any, associated 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.1.5 This international standard was developed in accor-dance with internationally
6、recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D4057 Practice f
7、or Manual Sampling of Petroleum andPetroleum ProductsD4175 Terminology Relating to Petroleum Products, LiquidFuels, and LubricantsD7684 Guide for Microscopic Characterization of Particlesfrom In-Service LubricantsG40 Terminology Relating to Wear and Erosion3. Terminology3.1 Definitions:3.1.1 abrasio
8、n, nwear by displacement of material causedby 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 leadi
9、ng to material transferbetween the two surfaces 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 th
10、e service life of a part isappreciably shortened 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, nwe
11、ar in which chemical or electro-chemical reaction 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
12、engineor resulting from wear. D41753.1.11 fatigue 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 r
13、efers only tothe nature of the motion without reference to the wear,corrosion, or other damage that may ensue. The term fretting isoften used to denote fretting corrosion and other forms of1This practice is under the jurisdiction of ASTM Committee D02 on PetroleumProducts, Liquid Fuels, and Lubrican
14、ts and is the direct responsibility of Subcom-mittee D02.96.06 on Practices and Techniques for Prediction and Determination ofMicroscopic Wear and Wear-related Properties.Current edition approved May 1, 2017. Published July 2017. Originally approvedin 2011. Last previous edition approved in 2011 as
15、D7690 11. DOI: 10.1520/D7690-11R17.2For referenced 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.Copyright ASTM Internation
16、al, 100 Barr Harbor 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
17、 and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1fretting wear. Usage in this sense is discouraged due to theambiguity that may arise. G403.1.13 fretting wear, nwear arising as a result of fretting.(See fretting.) G403.1.14 friction, nresistanc
18、e to sliding exhibited by twosurfaces in contact with each other. Basically there are twofrictional properties exhibited by any surface; static frictionand kinetic friction. D41753.1.15 impact wear, nwear due to collisions between twosolid bodies where some component of the motion is perpen-dicular
19、to the tangential plane of contact. G403.1.16 lubricant, nany material interposed between twosurfaces that reduces the friction or wear between them. D41753.1.17 lubricating oil, nliquid lubricant, usually compris-ing several ingredients, including a major portion of base oiland minor portions of va
20、rious additives. D41753.1.18 pitting, nin tribology, form of wear characterizedby the presence of surface cavities the formation of which isattributed to processes such as fatigue, local adhesion, orcavitation. G403.1.19 rolling, vin tribology, motion in a direction parallelto the plane of a revolut
21、e 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 fatigue, ndamage process in atriboelement subjected to repeated rolling contact loads, in-volving the initiation and propagation of fatigue
22、 cracks in orunder the contact surface, eventually culminating in surfacepits or spalls. G403.1.21 run-in, nin tribology, initial transition processoccurring in newly established wearing contacts, often accom-panied by transients in coefficient of friction, or wear rate, orboth, which are uncharacte
23、ristic 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 ofinitial operating conditions to a tribological system to improveits long term frictional or wear behavior, or both. (Synonym:break in,v,andwear
24、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 tribology, severe form of wear char-acterized by the formation of extensive grooves and scratchesin the direction of sliding. D4175, G403.1.25 sl
25、iding 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-micronsize particles, primarily carbon, created in the combustionchamber as products of incomplete combustion. D41753.1.27 spalling, nin trib
26、ology, 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 also resulting from impact events. G403.1.28 three-body abrasive wear, nform of abrasive wearin which wear is produced by loose particles
27、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 triboelement, none of two or more solid bodies thatcomprise a sliding, rolling, or abrasive contact, or a bodysubjected to impingement or cavitation
28、. (Each triboelementcontains one or more tribosurfaces.)3.1.29.1 DiscussionContacting triboelements may be indirect contact or may be separated by an intervening lubricant,oxide, or other film that affects tribological interactions be-tween them. G403.1.30 two-body abrasive wear, nform of abrasive w
29、ear inwhich 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 between the applied shear stressand rate of shear. It is sometimes called the coefficient ofdynamic viscosity. This value is thus a measure of t
30、heresistance 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. D41753.1.32 wear, ndamage to a solid surface, usually involvingprogressive loss or displacement of material, due to relativemotion between
31、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-like particles inthe form of loops or spirals generated due to hard, abrasiveparticles present between wearing surfaces of unequal hard-ness.3.
32、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 ferrograph areidentified to aid in establishing wear mode inside an oil-wettedpath of a machine.3.2.3 bichromatic microscope, noptical microscopeequi
33、pped with illumination sources both above and below themicroscope stage such that objects may be viewed either withreflected light, or with transmitted light, or with both simulta-neously.3.2.4 black oxides of iron, ngenerally small, black clusterswith pebbled surfaces showing small dots of blue and
34、 orangecolor. These are nonstoichiometric compounds containing amixture of Fe3O4,Fe2O3and FeO.3.2.5 contaminant particles, nparticles introduced froman extraneous 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
35、 ratio) of 15 m, and with major dimension-to-thickness ratios between5:1 and 30:1.3.2.26 spheres, nmetal spheres may be the result ofincipient rolling contact fatigue or they may be contaminantparticles from welding, grinding, coal burning and steel manu-facturing. Spheres may also be caused by elec
36、tro-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 are collected froma machine or engine as part of a routine condition monitoringprogram. A ferrogram is prepared from the sample to separatepart
37、icles from sample fluid. The ferrogram is subsequentlyexamined using an optical microscope to identify the types ofparticles present to aid in identifying the wear mode occurringin the oil-wetted path of the machine.4.2 In usual practice of a routine condition monitoringprogram, a ferrogram is not p
38、repared for every sample taken,but may be prepared when routine tests such as spectrochemi-cal analysis, particle counting or ferrous debris monitoringindicate abnormal results.4.3 The user of this practice employs consistent terminologyto achieve accepted and understandable interpretations whencomm
39、unicating instructions and findings based on ferrographicanalysis.5. Significance and Use5.1 The objective of ferrography is to diagnose the opera-tional condition of the machine sampled based on the quantityand type of particles observed in the oil. After break-in,normally running machines exhibit
40、consistent particle concen-tration and particle types from sample to sample. An increasein particle concentration, accompanied by an increase in sizeand severity of particle types is indicative of initiation of afault. This practice describes commonly found particles inin-service lubricants, but doe
41、s not address methodology forquantification of particle concentration.5.2 This practice is provided to promote improved andexpanded use of ferrographic analysis with in-service lubricantanalysis. It helps overcome some perceived complexity andresulting intimidation that effectively limits ferrograph
42、ic analy-sis to the hands of a specialized and very limited number ofpractitioners. Standardized terminology and common reportingformats provide consistent interpretation and general under-standing.5.3 Without particulate debris analysis, in-service lubricantanalysis results often fall short of conc
43、luding likely root causeor potential severity from analytical results because of missinginformation about the possible identification or extent ofdamaging mechanisms.5.4 Ferrographic analysis, as described in this practice,provides additional particle identification capabilities beyondmethods descri
44、bed in Guide D7684 for the following reasons:D7690 11 (2017)3(1) The ferrographic particle separation method is mag-netic thus making it possible to readily distinguish betweenferrous and nonferrous wear particles.(2) Ferrography separates ferrous (magnetic) particles bysize.(3) Deposition is on a g
45、lass substrate so that particles maybe examined using transmitted light as well as reflected lightallowing particle types to be identified that cannot be identifiedwhen examination is done using only reflected light.(4) Ferrograms may be heat treated providing importantdistinctions between ferrous a
46、lloy types (steel versus cast iron),further distinctions among various nonferrous alloys and dis-tinctions between inorganic and organic particles.5.5 Caution must be exercised when drawing conclusionsfrom the particles found in a particular sample, especially if thesample being examined is the firs
47、t from that type of machine.Some machines, during normal operation, generate wear par-ticles that would be considered highly abnormal in othermachines. For example, many gear boxes generate severe wearparticles throughout their expected service life, whereas just afew severe wear particles from an a
48、ircraft gas turbine oilsample may be highly abnormal. Sound diagnostics requirethat a baseline, or typical wear particle signature, be estab-lished for each machine type under surveillance.6. Apparatus6.1 Required Components:6.1.1 Ferrograph or Ferrogram MakerApparatus formagnetically separating par
49、ticles from fluids.6.1.2 Bichromatic MicroscopeAn optical microscope isrequired with dry metallurgical objective lenses and equippedwith a reflected light source and 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 with three objective lenses to givevarying degrees of magnification. The lo
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