Search Results for friction and wear properties

This article presents the mechanisms of polymer wear and quantifies wear in terms of wear rate (rate of removal of the material). Interfacial and bulk wear are discussed as well as a discussion on the wear study of "elastomers," "thermosets," "glassy thermoplastics," and "semicrystalline thermoplastics." The article also discusses the effects of environment and lubricant on the wear failures of polymers. It presents a case study on considering nylon as a tribological material and failure examples, explaining wear resistance of polyurethane elastomeric coatings and failure of an acetal gear wheel.

Tribology is the science and technology of interacting surfaces in relative motion. This article describes in detail the basic structural, operational, and interaction parameters of a tribosystem. The interaction parameters, which characterize the action of the operational parameters on the structural components in the system, consist of three important aspects: contact parameters, friction parameters, and wear parameters. These three aspects embody the complex mechanisms and relationships between the constituents of a tribosystem. The article concludes with information on the selection criteria of a material for wear applications.

Tribology is the study of contacting materials in relative motion and more specifically the study of friction, wear, and lubrication. This article discusses the classification and the mechanisms of friction, wear, and lubrication of polymers. It describes the tribological applications of polymers and the tribometers and instrumentation used to measure the tribological properties of polymers. The article discusses the processes involved in calculating the wear rate of polymers and the methods of characterization of the sliding interface. It provides information on the pressure and velocity limit of polymer composites and polymer testing best practices.

Polymers and polymer composites have become attractive for tribological applications due to their specific material properties. This article begins by discussing the fundamentals of polymer friction and wear. It summarizes the main polymer materials used in tribological applications. The article explains the effects of load, sliding velocity, and temperature on the friction coefficient. It describes three types of wear modes, namely, abrasive, adhesion, and fatigue. The article discusses the frictional behavior of polymer composites and polymer coatings. It concludes by providing information on tribotesting of polymers and polymer composites.

This article discusses the adhesion behavior of materials in low-pressure and vacuum environments and provides a schematic illustration of an apparatus for measuring adhesion and friction in ultrahigh vacuum. It describes the effects of low-oxygen pressures and vacuum environments on adhesion and friction, as well as the effects of defined exposure to oxygen on friction. The article discusses the wear of various metals in contact with ceramics, and alloying element effects on friction, wear, and transfer of materials. It also describes studies that characterize the contributions of surface contamination and chemical changes to tribology in low-pressure and vacuum environments.

This article discusses the importance of friction and wear and the role of lubricants in composites. It highlights the progress and developments in using different forms of carbon allotropes in composites for improved friction and wear performance of materials. The article focuses on the widely used form known as carbon black (CB) and shows how to deal with friction and wear of polymers and composites when gamma irradiation is involved. It also discusses the role of graphite in composite materials, which is widely used as a dry lubricant. The article examines the tribology of carbon nanotubes (CNTs) as components in composite materials. It also highlights some of the most pronounced examples of graphene use as a reinforcement agent for improving tribological performance in composite matrices. The article concludes with a discussion on the progress of research in diamond-containing composites.

There are huge numbers of publications and data available on ceramics, especially the basic types that cover their friction, wear, tribological mechanisms, high-temperature behavior, tribochemistry, and also lubrication conditions. This article summarizes the key overall research findings found in several comprehensive monographs. It discusses the types and properties of structural ceramics, as well as typical properties that govern the friction and wear of ceramics. The article reviews the superlow friction of silicon nitride and silicon carbide, and describes wear-protective hydrated tribochemical layers. It concludes with information on the tribological applications of structural ceramics and composites.

This article describes the numerous techniques used to measure friction. It provides a brief description of the historical development of friction testing. The article discusses the tests and equipment available for friction testing. It explains the procedural considerations that should be addressed to ensure that valid data are derived from a friction test. The article presents definitions of terms commonly used in tribology such as static friction, kinetic coefficient of friction, stick-slip behavior, and lubricated friction. It provides information on the precautions that must be taken to ensure valid test results. The article also describes how to report data and how to analyze these data.

This article focuses on environmental and application factors in solid friction. It covers the tribology of contact between a soft and hard material, including mechanisms and testing. The article describes the tribology of contact between a metal and tool during metalworking processes. It also discusses the tribology of metal friction at elevated temperatures.

Reinforced polymers (RPs) are widely used in structural, industrial, automotive, and engineering applications due to their ecofriendly nature and the potential to manipulate their properties. This article addresses the technical synthesis of RPs, referring to their tribological behavior, to provide insights into the contribution and interaction of influential parameters on the wear behavior of polymers. It provides a brief discussion on the effects of significant parameters on RP tribology. The article describes abrasive and adhesive wear and provides a theoretical synthesis of the literature regarding the wear mechanisms of RPs. It also describes the synthesis of abrasive wear failure of different types of RPs and highlights the contribution of these influential parameters. The article addresses the synthesis of adhesive wear failure of different types of RPs.

This article describes two variations of carbon-base coatings: diamondlike carbon (DLC) coatings and polycrystalline diamond (PCD) coatings. It discusses the basics of a few deposition methods as they apply to industrially relevant coatings. The methods include deposition of tungsten-containing hydrogenated amorphous carbon films, deposition of tetrahedral amorphous carbon films, and deposition of silicon-incorporated hydrogenated amorphous carbon films. The most common deposition technologies for diamond films are also discussed. The article provides information on surface preparation for DLC and diamond deposition. It also provides a discussion on the coating composition and structure, mechanical and tribological properties, and applications of DLC and diamond coatings. The quality control techniques for DLC and diamond coatings are specified to meet customer requirements and ensure repeatable quality.

This article focuses on friction, lubrication, and wear of internal combustion engine parts, improvements in which provide important gains in energy efficiency, performance, and longevity of the internal combustion (IC) engine systems. It discusses the types, component materials, and Friction and Wear Control of IC engine. The article explains the process of friction reduction by surface textures or coatings. It provides information on surface hardening of iron and steel, which is commonly employed for engine and powertrain components such as crankshafts, cams, and cylinder liners. The article also discusses advanced surface engineering technologies, such as diamondlike carbon coatings and surface texture technology. Information on thermal-spray methods that have led to improvements in engine components is also provided. The article describes IC engine-components wear, namely, piston assembly wear, valvetrain wear, cylinder-bore wear, and engine bearing wear. It concludes with information on inlet valve and seat wear of IC engine.

This article focuses on friction and wear of automotive and aircraft brakes. It provides a comparison of friction and wear behaviors, frictional characteristics, and frictional performance of the friction materials. The article describes the components of brake friction materials and the classifications of brake lining materials. It discusses the effect of formulation compositions and manufacturing processes and the effect of braking operation conditions. The article provides information on aircraft brake linings, which operate under a wide range of kinetic energy conditions. The morphology effect of graphite on automotive brake drum and disk is explained. The article also describes the characteristics of specific wear rates for both normal and local cast iron in automotive brake drums and disk rotors. It provides information on noises, vibrations, and harshness caused by brake pads. The article concludes with information on physical and chemical testing of brakes and toxicity of brake formulation and regulations.

This article describes the techniques for measuring friction, namely, inclined-plane method; friction test methods using weights and pulleys; friction tests of shafts and capstans; other types of friction tests, including standards; microscale friction tests; and friction testing under well-lubricated conditions. The procedural considerations that should be addressed to ensure that valid data are derived from a friction test are discussed. The article explains friction testing geometries, the major considerations implicit in their use as well as friction test parameters, such as speed and load. It also demonstrates how to report friction data and how these data can be entered into a database.

This article describes the surface modification treatments used to modify the tribological properties of titanium alloys. These include physical vapor deposition and thermochemical conversion treatments. The physical vapor deposition includes ion implantation, sputtering, evaporation, and ion plating surface modification treatments. The thermochemical conversion surface treatments include nitriding, carburizing, boriding, and solid lubrication.

This article begins with the basic concept of friction and with the general approaches that can be used to control or minimize it. It focuses on the factors influencing rolling friction: surface topography, composition, subsurface microstructure, and lubrication conditions. The article reviews the microscopic mechanisms generating friction. It concludes by discussing the three components of rolling friction: microslip at the interface, anelastic hyteresis losses, and surface roughness.

This article reviews friction and wear of various dental materials that have been studied by fundamental wear measurements, simulated service wear measurements, and clinical measurements. The materials include dental amalgam, composite restorative materials, pit and fissure sealants, dental cements, porcelain and plastic denture teeth, dental feldspathic porcelain and ceramics, endodontic instruments, periodontal instruments, and orthodontic wires. The article describes the correlations of properties such as the hardness, fracture toughness, and wear. It provides information on wear mechanism such as the sliding adhesive wear, two-body abrasion, three-body abrasion, erosion, and fatigue.

Friction and wear are important when considering the operation and efficiency of components and mechanical systems. Among the different types and mechanisms of wear, adhesive wear is very serious. Adhesion results in a high coefficient of friction as well as in serious damage to the contacting surfaces. In extreme cases, it may lead to complete prevention of sliding; as such, adhesive wear represents one of the fundamental causes of failure for most metal sliding contacts, accounting for approximately 70% of typical component failures. This article discusses the mechanism and failure modes of adhesive wear including scoring, scuffing, seizure, and galling, and describes the processes involved in classic laboratory-type and standardized tests for the evaluation of adhesive wear. It includes information on standardized galling tests, twist compression, slider-on-flat-surface, load-scanning, and scratch tests. After a discussion on gear scuffing, information on the material-dependent adhesive wear and factors preventing adhesive wear is provided.

Transition metal dichalcogenides (TMD) are solid lubricant materials, specifically, intrinsic solid lubricants, whose crystal structure facilitates interfacial sliding/shear to achieve low friction and wear in sliding contacts and low torque in rolling contacts. This article provides information on sliding friction and wear behavior of unbonded, bonded, and vapor-deposited pure and composite MoS 2 and WS 2 coatings. It discusses the rolling-torque behavior and applications of vapor-deposited pure and composite MoS 2 and WS 2 coatings. The article concludes with information on various forms of TMD lubrication, namely, oils, greases, microparticle and nanoparticle additives.