Tribology Letters

http://link.springer.com/journal/11249

List of Papers (Total 133)

Development of a Tribological Test Programme Based on Press Hardening Simulations

Press hardening is widely utilized to form ultra-high-strength steels characterized by a high strength-to-weight ratio for automotive components. Press hardening processes include heating boron–manganese steels to austenite phase, forming the steels at a high temperature, and cooling the formed blanks until the martensite phase is reached . However, press hardening processes lead ...

Influence of Post-treatment on the Microstructural and Tribomechanical Properties of Suspension Thermally Sprayed WC–12 wt%Co Nanocomposite Coatings

The potential to improve the tribomechanical performance of HVOF-sprayed WC–12Co coatings was studied by using aqueous WC–12Co suspensions as feedstock. Both as-sprayed and hot-isostatic-pressed (HIPed) coatings were studied. Mathematical models of wear rate based on the structure property relationships, even for the conventionally sprayed WC–Co hardmetal coatings, are at best ...

Positron Annihilation and Complementary Studies of Stainless Steel Exposed to Sandblasting at Different Angles

Defect studies in subsurface zone in stainless steel 304 AISI samples exposed to sandblasting were performed using positron annihilation spectroscopy techniques. Samples were sandblasted with a different impact angle. Conventional experiments based on positrons emitted directly from the radioactive source allowed us to detect vacancies on the dislocation edges in all samples; ...

Study of the Falling Friction Effect on Rolling Contact Parameters

The existence of a wheel–rail friction coefficient that depends on the slip velocity has been associated in the literature with important railway problems like the curving squeal and certain corrugation problems in rails. Rolling contact models that take into account this effect were carried out through the so-called Exact Theories adopting an exact elastic model of the solids in ...

Quantitative Viscosity Mapping Using Fluorescence Lifetime Measurements

Lubricant viscosity is a key driver in both the tribological performance and energy efficiency of a lubricated contact. Elastohydrodynamic (EHD) lubrication produces very high pressures and shear rates, conditions hard to replicate using conventional rheometry. In situ rheological measurements within a typical contact are therefore important to investigate how a fluid behaves under ...

Studies of the Influence of Temperature and the Energy State of the Surface Layer of Adsorbents on Wall Effects in Soap-Based Greases

This paper presents the results of studies of wall effects in commercial soap-based greases LT4-S2 and HUTPLEX EP-2, thickened with, respectively, lithium 12-hydroxystearate and overbased calcium sulfonate. The studies were conducted in the presence of five different materials: copper alloy C11000, bronze B476, EPDM rubber and PTFE and PU thermoplastics. The influence of the energy ...

Indentation Hardness Measurements at Macro-, Micro-, and Nanoscale: A Critical Overview

The Brinell, Vickers, Meyer, Rockwell, Shore, IHRD, Knoop, Buchholz, and nanoindentation methods used to measure the indentation hardness of materials at different scales are compared, and main issues and misconceptions in the understanding of these methods are comprehensively reviewed and discussed. Basic equations and parameters employed to calculate hardness are clearly ...

Effect of Base Oil Structure on Elastohydrodynamic Friction

The EHD friction properties of a wide range of base fluids have been measured and compared in mixed sliding–rolling conditions at three temperatures and two pressures. The use of tungsten carbide ball and disc specimens enabled high mean contact pressures of 1.5 and 2.0 GPa to be obtained, comparable to those present in many rolling bearings. The measurements confirm the importance ...

Elastic Waves of a Single Elasto-Hydrodynamically Lubricated Contact

Elastic waves are widely used for condition monitoring of rolling element bearings through vibration or acoustic emission measurements . While vibration signals are understood to a high degree due to many scientific investigations as well as a long history of usage in the field, acoustic emission signals of rolling element bearings are poorly understood. Therefore, this ...

Absolute Measurement of Elastic Waves Excited by Hertzian Contacts in Boundary Restricted Systems

In most applied monitoring investigations using acoustic emission, measurements are carried out relatively, even though that limits the use of the extracted information. The authors believe acoustic emission monitoring can be improved by instead using absolute measurements. However, knowledge about absolute measurement in boundary restricted systems is limited. This article ...

Skin Microstructure is a Key Contributor to Its Friction Behaviour

Due to its multifactorial nature, skin friction remains a multiphysics and multiscale phenomenon poorly understood despite its relevance for many biomedical and engineering applications (from superficial pressure ulcers, through shaving and cosmetics, to automotive safety and sports equipment). For example, it is unclear whether, and in which measure, the skin microscopic surface ...

The Tribofilm Formation of ZDDP Under Reciprocating Pure Sliding Conditions

The anti-wear and anti-seizure performance and action mechanisms of zinc dithiophosphate (ZDDP) have been investigated under reciprocating pure sliding conditions to simulate piston ring and cylinder liner assembly, using new techniques. The Mini Traction Machine–Space Layer Imaging is a useful method for monitoring tribofilm formation by ZDDPs. However, tests are generally carried ...

Airborne Wear Particles Generated from Conductor Rail and Collector Shoe Contact: Influence of Sliding Velocity and Particle Size

The mechanical wear of train components is one of the main sources of airborne particles in subway air. A certain contribution is suspected to derive from third-rail systems due to the sliding of two metallic surfaces between conductor rail and collector shoe during operation. In this study, a pin-on-disc apparatus was used to simulate the friction between such two sliding partners ...

A Stress-Criterion-Based Model for the Prediction of the Size of Wear Particles in Boundary Lubricated Contacts

In this paper, the formulation and validation of a model for the prediction of the wear particles size in boundary lubrication is described. An efficient numerical model based on a well-established BEM formulation combined with a mechanical wear criterion was applied. The behavior of the model and particularly the influence of the initial surface roughness and load was explored. ...

The Relationship Between Friction and Film Thickness in EHD Point Contacts in the Presence of Longitudinal Roughness

This study investigates friction and film thickness in elastohydrodynamic contacts of machined, rough surfaces, where roughness is dominated by longitudinal ridges parallel to the rolling/sliding direction. A ball-on-disc tribometer was used to simultaneously measure friction and film thickness in rough contacts as well as with nominally smooth specimens for comparison. The studied ...

Effect of a Fatty Acid Additive on the Kinetic Friction and Stiction of Confined Liquid Lubricants

The kinetic friction and stiction properties of the dilute solution of palmitic acid (PA, friction modifier additive) in poly(α-olefin) (PAO) confined between molecularly smooth mica surfaces were investigated using the surface forces apparatus (SFA). The results were contrasted with those of confined PAO system; the effects of PA additive on the confined film structure and ...

The Influence of Slide–Roll Ratio on ZDDP Tribofilm Formation

The anti-wear performance and action mechanisms of zinc dithiophosphate (ZDDP) have been investigated under various test conditions. The Mini Traction Machine–Space Layer Imaging (MTM–SLIM) is a widely used and useful method for monitoring tribofilm formation by ZDDPs. However, tests are generally carried out in mixed sliding–rolling conditions, typically between 50 % SRR ...

Formation of Subsurface Zone Induced by Sliding Wear in Zirconium Studied by Positron Lifetime Spectroscopy

The zone below the surface in pure Zr exposed to dry sliding is the subject of studies using positron lifetime methods. New type of the defect depth profile is observed. The zone contains dislocations and vacancy clusters which occur only at a certain depth from the worn surface. The size of the vacancy clusters decreases with the depth increase. The total depth of the subsurface ...

An Analytical Approach for Prediction of Elastohydrodynamic Friction with Inlet Shear Heating and Starvation

An analytical friction model is presented, predicting the coefficient of friction in elastohydrodynamic (EHD) contacts. Three fully formulated SAE 75W-90 axle lubricants are examined. The effect of inlet shear heating (ISH) and starvation is accounted for in the developed friction model. The film thickness and the predicted friction are compared with experimental measurements ...

Wear Mechanisms of Hydrogenated DLC in Oils Containing MoDTC

Diamond-Like Carbon (DLC) coatings are well known for offering excellent tribological properties. They have been shown to offer low friction and outstanding wear performance in both dry and lubricated conditions. Application of these coatings for automotive components is considered as a promising strategy to cope with the emerging requirements regarding fuel economy and durability. ...

Nonequilibrium Molecular Dynamics Investigation of the Reduction in Friction and Wear by Carbon Nanoparticles Between Iron Surfaces

For the successful development and application of novel lubricant additives, a full understanding of their tribological behaviour at the nanoscale is required, but this can be difficult to obtain experimentally. In this study, nonequilibrium molecular dynamics simulations are used to examine the friction and wear reduction mechanisms of promising carbon nanoparticle friction ...

Classical EHL Versus Quantitative EHL: A Perspective Part II—Super-Arrhenius Piezoviscosity, an Essential Component of Elastohydrodynamic Friction Missing from Classical EHL

Ninety years of high-pressure measurements with many different types of viscometers have shown that faster-than-exponential (super-Arrhenius) pressure dependence of viscosity is universal for glass-forming liquids and, therefore, all typical liquid lubricants. Dielectric spectroscopy at elevated pressure also yields super-Arrhenius response in the dependence on pressure of the ...

Monitoring of Running-in of an EHL Contact Using Contact Impedance

Running-in is an important process for elasto-hydrodynamic lubricated contacts, which affect both service life and operating performance. However, the possibilities of monitoring running-in are still poor. Therefore, the properties of electrical contact impedance as a monitoring tool were studied by using an in-house made ball on disc apparatus. The contact impedance was monitored ...