Mechanics and Chemistry in Lubrication

Although it is widely recognized that friction, wear and lubrication are linked together in a single interdisciplinary complex of scientific learning and technological practice, fragmented and specialized approaches still predominate. In this book, the authors examine lubrication from an interdisciplinary viewpoint. They demonstrate that once the treatment of lubrication is released from the confines of the fluid film concept, this interdisciplinary approach comes into full play. Tribological behavior in relation to lubrication is then examined from two major points of view: one is mechanical, not only with respect to the properties and behavior of the lubricant but also of the surfaces being lubricated. The other is chemical and encompasses the chemistry of the lubricant, the surfaces and the ambient surroundings. It is in the emphasis on the interaction of the basic mechanical and chemical processes in lubrication that this book differs from conventional treatments.

Contents

1. Introduction

1.1. What Is Friction

1.2. Friction and Wear

1.3. Tribology

1.4. Some Further Statements about Lubrication

References

2. Simple Hydrodynamic Theory: The Reynolds Equation in Two Dimensions

2.1. Beauchamp Tower's Bearing Experiments

2.2. A n Engineering Derivation of the Two-Dimensional Reynolds Equation

2.3. The Reynolds Equation in Use: The Plane Slider Bearing

2.4. Energy Losses in the Hydrodynamic Lubrication of Bearings

2.5. The Pivoted Slider Bearing: Design Variables

2.6. The Full Journal Bearing

2.6.1. Application of the Reynolds Equation to the Full Journal' Bearing

2.6.2. Friction in the Full Journal Bearing

References

Appendix

3. Some Advanced Aspects of Hydrodynamic Lubrication

3.1. The Classical Fluid

3.1.1. Stress Analysis of a Fluid

3.1.2. The Simple Visccus Fluid

3.2. The Navier-Stokes Equations

3.3. The Generalized Reynolds Equation

3.4. Squeeze Films

3.5. Elastohydrodynamic Lubrication

3.5.1. Elastohydrodynamic Theory

3.5.2. Some Elastohydrodynamic Solutions: Line Contact

3.5.3. Elastohydrodynamic Solutions for Point Contact

3.5.4. Experimental Observations of Elastohydrodynamic Lubrication

References

4. The Nature and Properties of Liquids

4.1. The Properties of Liquids and Lubrication

4.2. Newtonian and Non-Newtonian Viscosity

4.3. Capillary Viscometry

4.3.1. Newtonian Flow through a Capillary

4.3.2. Non-Newtonian Capillary Flow

4.3.3. Sources of Error in Capillary Viscometry

4.4. Capillary Viscometers

4.4.1. The Cannon-Fenske Viscometer

4.4.2. Capillary Viscometry Under Pressure

4.5. Rotational Viscometry and Viscometers

4.5.1. The Couette Viscometer

4.5.2. The Cone-and-Plate Viscometer

4.6. Rolling-Ball and Falling-Sinker Viscometers

4.7. Orifice Viscometers

4.8. Influence of Temperature and Pressure on Viscosity

4.8.1. The Walther Equation and ASTM Viscosity-Temperature Charts

4.8.2. The Viscosity Index

4.8.3. Pressure and Viscosity

4.9. Theories of Viscosity and the Molecular Structure of Liquids

4.10. Compressibility and Bulk Modulus

4.11. The Role of Compressibility in Lubrication

References

5. Gases as Lubricating Fluids

5.1. Fundamentals of Gas Film Lubrication

5.2. Gas-Lubricated Bearings

5.3. Properties of Gases

References

6. Measurement of Fluid Film Thickness and Detection of Film Failure

6.1. Electrical Methods

6.1.1. Film Thickness by Electrical Resistance

6.1.2. Film Thickness by Electrical Capacitance

6.2. ODtical Interferometry

6.3. X-Ray Transmission

6.4. Summarizing Discussion of Film Thickness Measurement

6.5. The Meaning of Film Failure

6.6. Electrical Methods of Detecting Film Failure

6.7. Detection of Fluid Film Failure by Friction or by Examination of Surface Condition

References

7. Friction: Phenomenology. Detection and Measurement

7.1. Basic Phenomenology of the Friction of Solid Bodies

7.2. Simple Behavioral Aspects of Static and Kinetic Friction

7.3. Experimental Arrangements for Detection and Measurement of Friction

7.3.1. Devices Utilizing Elastic Deflection

7.3.2. Dead-Weight Tangential Traction Devices

7.3.3. Inclined Plane Method for Static Friction

7.3.4. Damping of Oscillatory Motion

References

8. Friction: Mechanisms and Analysis

8.1. A Simple Mechanism for the Friction of Solid Metallic Bodies

8.2. Extension of the Adhesive-Junction Model for Friction

8.3. Intermittent Motion in Frictional Sliding: Stick-Slip Oscillation

8.4. Frictionally Induced Quasiharmonic Vibration

8.5. The Nature of Static and Kinetic Friction

8.6. Sliding Speed and Friction

8.7. Non-Adhesional Mechanisms for Friction

References

9. Lubricated Friction

9.1. The Contact and Friction of Clean Surfaces

9.2. The Influence of Oxides on the Friction of Metals

9.3. Lubricated Friction: The Behavioristic View

9.4. A Theoretical View of Lubricated Friction

References

10. Lubricant Additive Action . I. Basic Categories and Mechanisms

10.1. What is a Lubricant Additive

10.2. Classification and Nomenclature

10.3. Interposed Adsorption Films

10.3.1. Simple Absorbed Films

10.3.2. Chemisorbed Films

10.4. The Additive Action of Adsorbed Films

10.4.1. Durability of Films

10.4.2. Influence of Temperature on Adsorbed Films and Friction

10.4.3. Thermodynamics of Adsorption and Lubrication

10.4.4. Other Physicochemical Influences in Adsorbed Film Behavior

10.5. Chemically Deposited Films

10.5.1. Polymeric Condensation Films

10.5.2. Surface Resin ("Friction Polymer")

10.6. Interaction Films

10.7. Asperity Junction-Growth Inhibition

References

11. Lubricant Additive Action. II. Chemical Reactivity and Additive Functionality

11.1. A Basic View of Reactions between Additives and Metal Surfaces

11.2. Chemical Structures in Additives and Mechanisms of Additive Action

11.2.1. Sulfur Compounds: Chemical Reactions

11.2.2. Sulfur Compounds: Lubricant Additive Action

11.2.3. Chlorine Compounds: Chemical Reactions

11.2.4. Chlorine Compounds: Lubricant Additive Action

11.2.5. PhosDhorus COmDOundS: Chemical Reactions and Additive Action

11.2.6. Phosphorus and Other Key Elements: Dithiophosphates (Phosphorodithioates) etc

11.3. The Action of Multicomponent Additives

11.3.1. Multicomponent Additives with Sulfur and Chlorine

11.3.2. Multicomponent Additives with Phosphorus and Chlorine

11.3.3. Sulfur and Fatty Esters in Multicomponent Additives

11.3.4. Interference Effects with Multicomponent Additives

References

12. Contact of Solid Bodies

12.1. Surfaces and Surface Roughness

12.1.1. Descriptive Surface Topography

12.1.2. The Metrics of Surface Roughness

12.2. Contact and Adhesion

12.2.1. Simple Deformation Models of Contact

12.2.2. Adhesion and Separation

12.3. Characterization of Surfaces from Profile Data

12.4. Surface Topography and the Mechanics of Asperity Contact

12.5. Experimental Studies of Contact and Adhesion

12.6. The Tribological Significance of Contact and Adhesion

References

13. Wear: Basic Principles and General Behavior

13.1. A Basic Definition of Wear

13.2. Phenomenological Wear

13.2.1. Wear in Pure Sliding

13.2.2. Mixed Sliding and Rolling

13.2.3. Pure Rolling

13.2.4. Impinging Contact

13.2.5. Dry and Lubricated Wear

13.2.6. Wear of Non-Metals

13.3. Mechanistic Processes in Phenomenological Wear

13.3.1. Adhesion and Transfer

13.3.2. Plastic Deformation Processes

13.3.3. Fatigue Mechanisms

13.3.4. Chemical Reaction Processes

13.3.5. Combinations of Mechanistic Processes

13.4. Nomenclature

13.5. Wear Models

13.5.1. Wear Models and Asperity Contact

13.5.2. Models for Constant Wear Rate

13.5.3. Wear with Variable Rate

13.5.4. Geometrical Influences in Wear Models

13.5.5. Physical Parameters in Wear Models

13.6. Catastrophic Wear Damage

References

14. Aspects of Lubricated Wear

14.1. Lubricated Wear by Penetration of the Fluid Film

14.1.1. Wear and Partial Elastohydrodynamic Lubrication

14.1.2. Wear and Mixohydrodynamic Lubrication

14.2. Compounded Lubricants and Wear

14.2.1. Reaction-Rate Theories of Wear in the Presence of Compounded Lubricants

14.2.2. Reaction Rate Processes and Phenomenological Wear

14.3. The Control of Scuffing

References

15. Temperature Effects in Friction. Wear and Lubrication

15.1. Interfacial Temperature and Rubbing

15.1.1. A Descriptive Model for Interfacial Temperature in Rubbing

15.1.2. Calculation of Interfacial Temperature by Continuum Heat Conduction Theory

15.1.3. A Stochastic Model for Interfacial Temperature Generated at Discrete Sites

15.2. Experimental Observations of Interfacial Temperature

15.2.1. The Dynamic Thermocouple

15.2.2. The Embedded Thermocouple

15.2.3. The Strip Thermistor

15.2.4. Emission of Infrared Radiation

15.3. Ambient Temperature Effects

15.4. Effects of Temperature on Friction and Wear

15.5. Effects of Temperature on Lubrication and Lubricants

References

16. Petroleum Lubricating Oils

16.1. Processing of Petroleum Lubricants

16.2. Nomenclature and Classification of Petroleum Oils

16.3. Structure in Lubricating Oils by Direct Techniques

16.3.1. Extraction, Chromatographic Adsorption, Distillation and Mass Spectrography

16.3.2. Distillation, Extraction, Chromatographic Adsorption, Thermal Diffusion and Mass Spectrography

16.3.3. Mass Spectrography of Refinery-Run Fractions

16.3.4. Nature of the Alkyl and Aromatic Structures

16.4. Type Structures in Lubricating Oils by Correlation with Physical Properties: Indirect Methods

16.5. Type Structures in the Performance of Petroleum Oils as Lubricants

References

17. Non-Petroleum Liquids as Lubricants

17.1. Chemical Types and Structures

17.2. Chemical Types and Properties of Synthetic Lubricants

17.3. Applications of Synthetic Lubricants

References

18. Lubricating Grease

18.1. Basic Aspects of Lubricating Grease Structure

18.2. The Manufacture of Lubricating Grease

18.3. Further Consideration of Grease Structure

18.3.1. Bleeding and Permeability

18.3.2. Consistency and Penetration

18.4. The Flow of Greases

18.5. Grease as a Lubricant in Service

References

19. Lubrication by Solids

19.1. Classification and Terminology

19.2. Layer-Lattice Inorganic Solids as Lubricants

19.2.1. Molybdenum Disulfide as a Luricating Lamellar Solid

19.2.2. Graphite as a Solid Lubricant

19.2.3. Graphite Fluoride as a Solid Lubricant

19.2.4. Boron Nitride as a Solid Lubricant

19.2.5. Other Layer-Lattice Inorganic Solids as Lubricants

19.3. Lubrication by Non-Lamellar Inorganic Solids and by Soft Metals

19.4. Organic Solids as Lubricants

19.5. The Technological Utilization of Solid Lubricants

References

Author Index

Subject Index