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4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/AIR5433BAEROSPACEINFORMATION REPORT AIR5433 REV. BIssued 2001-05 Revised 2014-01
5、Superseding AIR5433A Lubricating Characteristics and Typical Properties of Lubricants Used in Aviation Propulsion and Drive Systems RATIONALE Since issuance of AIR5433A, it was discovered that the pressure viscosity coefficient values for 3 and 4 cSt oils listed in Table 3 were in error. In addition
6、, the specific heat units in Table 6 were incorrect. After review in the E-34C Lubricating Characteristics Subcommittee, these issues have been resolved in this revision. INTRODUCTION This SAE Aerospace Information Report (AIR) is intended as a guide toward standard practice, but may be subject to c
7、hange to keep pace with experience and technical advances. Hence, its use, where flexibility of revision is impractical, is not recommended. The information contained herein is an attempt to establish guidelines for the selection of properties governing the lubricating characteristics of lubricants
8、to be used in current and future aviation propulsion and drive systems. It is the intent of the SAE Committee E-34 on Propulsion Lubricants, that this document reflects currently accepted thinking in the industry and government agencies concerned with the lubrication of components in aviation primar
9、y propulsion systems, and associated power transfer gearboxes and transmissions. The content of this AIR is the result of communication among lubricant manufacturers, hardware manufacturers, lubricant specialists, tribologists, lubricant specifiers, and lubricant users. Continued communication will
10、be encouraged to maintain the information contained herein as current as possible. Users are advised that they can contribute to subsequent changes and additions to this document by their comments, suggestions and criticism. In present standards, some properties of importance in determining lubricat
11、ing ability and the methods to quantify these properties tend to be ignored and in some cases there are no standardized test methods. Because these properties are important to designers, they are included in this document even if methods are not specified or standardized. In these cases, typical val
12、ues obtained by particular methods are presented. It is intended that by including these data, focus will be brought on the deficiencies in these areas. It must also be recognized that the selection of properties relevant to lubricating characteristics must be made in the light of the other characte
13、ristics necessary or desirable in the lubricant. This document is not intended to specify the properties of fluids optimized for lubricating ability; instead it is intended to provide the guidance to be considered, along with the other requirements for the application, in determining the values to b
14、e specified for each property. Trade-off in the selection of limits for various properties must be made based on the relative impact of these properties on each other and on the system. SAE INTERNATIONAL AIR5433B Page 2 of 43 TABLE OF CONTENTS 1. SCOPE 42. REFERENCES 42.1 Applicable Documents 42.2 D
15、efinitions and Terminology . 42.3 Symbols and Abbreviations 53. FUNDAMENTALS OF LUBRICATION AND LUBRICANT PROPERTIES . 73.1 Lubricant Function . 73.2 Lubrication and Failure Mechanisms 83.2.1 Introduction . 83.2.2 Types of Contacts . 83.2.3 Structural Elements of a Lubricated Contact 93.2.4 Stress F
16、ields of a Lubricated Contact . 103.2.5 Lubrication Mechanisms . 103.2.6 Failure Processes . 134. PROPERTIES AND ATTRIBUTES . 164.1 Properties Significance . 174.1.1 Properties in Hydrodynamic Lubrication . 174.1.2 Properties in Elastohydrodynamic Lubrication 184.1.3 Properties for EHD Traction 234.
17、1.4 Properties for Boundary Lubrication . 244.1.5 Mixed Film Lubrication 255. COMMONLY USED LUBRICANT PROPERTIES FOR AIRCRAFT ENGINE AND POWER SYSTEMS 285.1 Background . 285.2 Properties and Test Methods for Lubricants Used in Aircraft Propulsion Systems 296. NOTES 37APPENDIX A LUBRICANT FILM THICKN
18、ESS CALCULATION 38FIGURE 1 STRUCTURAL ELEMENTS OF A LUBRICATED CONTACT 9FIGURE 2 EHD LUBRICATION . 11FIGURE 3 SURFACE FILMS FROM BOUNDARY LUBRICATION MECHANISMS . 12FIGURE 4 FIVE KEY TRIBOLOGY PARAMETERS 13FIGURE 5 PRESSURE-VISCOSITY COEFFICIENTS FOR 5 CST QUALIFIED PRODUCTS . 20FIGURE 6 AVERAGE PRE
19、SSURE-VISCOSITY COEFFICIENT REPRESENTING 5 CST QUALIFIED PRODUCTS 21FIGURE 7 COMPARISON OF THE ISOTHERMAL AND THERMAL SOLUTION FOR THE LUBRICANT FILM THICKNESS IN A GAS TURBINE ENGINE BEARING AS A FUNCTION OF TEMPERATURE . 22FIGURE 8 EFFECT OF STRESS AND SLIP ON TRACTION COEFFICIENT 23FIGURE 9 THE I
20、NFLUENCE OF TEMPERATURE AND SLIP ON TRACTION COEFFICIENT . 24FIGURE 10 BOUNDARY FILM FROM ANTI-WEAR ADDITIVE TRICRESYL PHOSPHATE (TCP) 25FIGURE 11 TRANSITION FROM EHD TO MIXED FILM LUBRICATION . 26FIGURE 12 PERFORMANCE MAP IN TERMS OF ENTRAINING AND SLIDING VELOCITY . 27FIGURE 13 LOAD CAPACITY TEST
21、SHOWING SCUFFING AND WEAR PERFORMANCE . 28TABLE 1 LUBRICANT PROPERTY SUMMARY FOR AIRCRAFT PROPULSION SYSTEMS KINEMATIC VISCOSITY . 29TABLE 2 BRICANT PROPERTY SUMMARY FOR AIRCRAFT PROPULSION SYSTEMS TEMPERATURE- VISCOSITY DATA 30TABLE 3 LUBRICANT PROPERTY SUMMARY FOR AIRCRAFT PROPULSION SYSTEMS PRESS
22、URE- VISCOSITY COEFFICIENT 31TABLE 4 LUBRICANT PROPERTY SUMMARY FOR AIRCRAFT PROPULSION SYSTEMS LOAD RATING (WEAR AND SCUFFING) . 32SAE INTERNATIONAL AIR5433B Page 3 of 43 TABLE 5 LUBRICANT PROPERTY SUMMARY FOR AIRCRAFT PROPULSION SYSTEMS TRACTION COEFFICIENT 33TABLE 6 LUBRICANT PROPERTY SUMMARY FOR
23、 AIRCRAFT PROPULSION SYSTEMS SPECIFIC HEAT 34TABLE 7 LUBRICANT PROPERTY SUMMARY FOR AIRCRAFT PROPULSION SYSTEMS DENSITY 35TABLE 8 LUBRICANT PROPERTY SUMMARY FOR AIRCRAFT PROPULSION SYSTEMS THERMAL CONDUCTIVITY . 36TABLE 9 LUBRICANT PROPERTY SUMMARY FOR AIRCRAFT PROPULSION SYSTEMS ELECTRICAL CONDUCTI
24、VITY . 37SAE INTERNATIONAL AIR5433B Page 4 of 43 1. SCOPE This SAE Aerospace Information Report (AIR) establishes guidance for the specification of formulated lubricant properties which contribute to the lubricating function in bearings, gears, clutches and seals of aviation propulsion and drive sys
25、tems. 2. REFERENCES 2.1 Applicable Documents The following publications form a part of this document to the extent specified herein. The latest issue of SAE publications shall apply. The applicable issue of the other publications shall be the issue in effect on the date of purchase. In the event of
26、conflict between the text of this document and references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 1 Anonymous. Glossary of Terms and Definitions in the Field
27、 of Friction, Wear and Lubrication - Tribology, Research Group on Wear Engineering Materials, Organization for Economic Cooperation Development, Paris, 1969. 2 Cameron, A., “Principles of Lubrication”, Longmans, London, 1966, P.31. 3 Annual Book of ASTM Standards 2000, Section 5, Petroleum Products,
28、 Lubricants, and Fossil Fuels, Volume 05.01 Petroleum Products and Lubricants (I): D 56 D 2596 4 Cheng, H.S., Micro-Elastohydrodynamic Lubrication, U.S. National Congress of Applied Mechanics, 21-25 June 1982, pp.161-170. 5 Hamrock, Bernard J., Fundamentals of Fluid Film Lubrication, 1994. McGraw-Hi
29、ll. ISBN 0070259569. 6 Gupta, P.K., Cheng, H.S., Forster, N.H., Schrand, J.B., “Viscoelastic Effects in MIL-L-7808 Type Lubricant, Part I: Analytical Formulation, Trib. Trans. Vol. 35, 2, pp 269-274 (1992). 2.2 Definitions and Terminology The following terms are defined according to the definitions
30、given in Reference 1 and according to the customary engineering descriptions used in the aerospace community. FATIGUE - Removal of particles detached by fatigue arising from cyclic stress variation. (1) Spalling is removal of material by fatigue resulting from the global contact stress. It can be su
31、rface or subsurface initiated; (2) Pitting is removal of material by fatigue resulting from local stress within the contact. It is surface or near surface initiated. Fatigue pits are ofsmaller scale than fatigue spalls; (3) Micro-pitting (Peeling, Frosting) This type of fatigue is characterized by s
32、urface initiated spalling in the order of 5 to 13 micron (0.0002 to 0.0005 inch) in depth which occurs where the surface finishes have many asperities greater than the lubricant film thickness. Normally micro-pitting is only a slight distress to the contactsurface and appears to be nothing more than
33、 a frosted appearance. FRETTING - A wear phenomena occurring between two surfaces having oscillatory relative motion of small, 3, wear, scuffing, and micro-pitting (or micro-spalling) are mostly eliminated. Surface initiated fatigue and wear are controlled by h/ as a result of affecting normal and t
34、angential stress on an asperity scale. Its connection with surface-initiated fatigue seems to be more obvious than failure modes associated with wear or scuffing. The latter failure modes generally appear at low lambda, less than 1, where the concept of lambda loses some of its meaning. When the com
35、bined roughness () is the same order of magnitude as the film thickness (h), the surface topography becomes intimately involved in the lubrication process itself in the form of micro-EHD lubrication. Local hydrodynamic or EHD pressures can be generated at asperity sites or topographical features to
36、actually depress these features and boost local film formation. Micro-EHD lubrication should not be confused with boundary lubrication. Micro-EHD lubrication can also affect the friction, or traction within the contact, see Reference 4. 3.2.6 Failure Processes 3.2.6.1 Five Key Parameters The challen
37、ges of lubricant formulation, along with bearing and gear design, are to invoke lubrication mechanisms of full-film EHD, partial-film EHD and boundary film lubrication and to avoid failure mechanisms associated with wear, scuffing, and fatigue. With the exception of hydrodynamic and EHD film thickne
38、ss prediction, lubricant performance is determined by testing and service experience. Tribological testing must capture the micro-scale lubrication and failure mechanisms controlling performance and somehow link the testing results to the macro-scale design space that the design engineer can utilize
39、. Five key tribology parameters have been found to be effective in linking tribological mechanisms in service with testing and design. The five parameters, which are derived from EHD theory, are shown in Figure 4. FIGURE 4 FIVE KEY TRIBOLOGY PARAMETERS The entraining velocity (Ue) controls the forma
40、tion of EHD film thickness through the generation of pressure in the inlet region. The sliding velocity (Us) controls the shear and heat generation within the Hertzian region. The film thickness-to-surface roughness ratio (h/), or Lambda ratio ( ), controls the degree of asperity interaction. The co
41、ntact stress is considered on a global Hertzian contact scale and a local asperity scale. Wear, micro-pitting and micro-scuffing are generally initiated on a local scale and subsequently propagated to a global scale. Contact temperature (Tc) is considered the sum of the bulk temperature (Tb) and the
42、 friction-generated flash temperature (Tf). The contact temperature controls reaction rates between the lubricant and surface material. It also controls the shear properties at the interface. 3.2.6.2 General Failure Scenarios The five key tribological parameters provide an engineering linkage to lub
43、rication and failure scenarios. With little or no asperity penetration ( 1), major failures of wear, scuffing, and surface initiated fatigue are avoided. It is generally recognized that the loss of an EHD film is a necessary, but not sufficient, condition for failure mechanisms. Perhaps the most imp
44、ortant quantity in connection with failure is the deformation attributes of the near-surface region. It is unfortunate that there is little understanding of near-surface mechanical properties or the attributes needed to complement the various lubricating mechanisms to prevent failure. To maintain su
45、rface integrity, the near-surface region must prevent micro-fracture and maintain a viable surface finish even in the presence of some plastic flow. Entraining velocity, Ue= (U1+ U2)Degree of asperity penetration (h/)Contact temp (Tc= Tbulk+ Tflash)Sliding velocity, Us= U1U2Contact stress (incl. asp
46、erity stress)K15)6XUIDFHILOP56OLGLQJYHORFLW1U2U1hSAE INTERNATIONAL AIR5433B Page 14 of 43 The severity of asperity interaction is reflected in the normal load FN(see Figure 3). The normal load on the asperity is influenced by the thickness (h) of lubricant film that is generated. The shear force, FS
47、, is influenced by the various surface films and micro-EHD lubricant films, along with the flow properties in the near-surface region. The exact mechanism whereby shear stress is applied to the near-surface region is not well understood. This could come about through metal-to-metal adhesion, or poss
48、ibly through shear stresses applied locally through a thin lubricant film. The severity of interaction is important to the initiation and propagation of the events toward failure. The severity of interaction will determine whether the result is (1) a benign elastic encounter, (2) a further accumulat
49、ion of plastic fracturesites that can lead to the generation of wear particles (e.g., micro-pitting, or polishing wear debris), (3) oxidative or corrosive wear, or (4) the advancing of adhesive material transfer, which can lead to adhesive wear or scuffing. Failure can occur through four basic processes of adhesion, plastic deformation, fatigue and chemical reactions. The r
