Tribological Approach Research Articles

Simulation Research on Dynamic Tribological Systems of Plain Bearing

The research method of the inner friction and wear characteristics of plain bearing which is mainly conducted currently, is to analyze the all factors that affect the friction and wear of plain bearing from the perspective of wear, and to build friction and wear model, and then to conduct the research on the model. The article establishes the friction and wear dynamics model on base of the tribological systems approach, and on the base of analyzing the internal friction system and inner process of Tribology system of plain bearing. The article conducts the research on the friction and wear characteristics of plain bearings, and studies the relationship between the inner temperature rise and the heat on the base of simulation of the dynamics model. The consistency of the simulation results and academic calculation of the dynamic model proves that the dynamic model, which is established in the article, is correct.

Understanding dental wear

Dental wear is deterioration as a result of use. It has existed since the beginning of mankind in all civilizations and cultures. It occurred routinely and intensely in early populations but was considered to be a physiological process. Ideas about dental wear are not as clear today because while it is less pronounced it sometimes appears in pathological patterns. Moreover, it is produced by many complex mechanisms acting in synchrony or sequentially, in synergy or additive, in patterns that often mask its true origins. In an effort to ameliorate the means of preventing and diagnosing dental wear and improving our understanding of its diverse manifestations, the primary objective of this article will be to present the principal mechanisms that produce it as well as their consequences. To organize our presentation we have adopted a tribological approach, focusing on the friction, wear, and lubrication of interacting surfaces.

Effect of slurry parameters on material removal rate in multi-wire sawing of silicon wafers: a tribological approach

The main goals for the silicon wafering industry are to improve the surface quality of wafers by reducing the total thickness variation and subsurface defects and to increase the production by reducing the wafer thickness. To attain these goals, it is important to understand the material removal mechanisms involved in the process, which at the moment are little understood and explored. In this study, the effect of slurry parameters on the wear rate and surface roughness of solar grade silicon have been investigated using a tribological approach. A reciprocating pin-on-plate tribometer has been used to simulate the abrasion process occurring in a slurry-based multi-wire silicon saw. The tribological system consisted of silicon, SiC slurry, and stainless steel counterpart. The results showed that a narrow size distribution of the SiC particles in the slurry increases the wear rate and improves the surface quality. The shape factors of the SiC particles in the slurry were also investigated and revealed that particles with lower degree circularity and higher aspect ratio led to lower roughness.

Dynamic Mechanical Properties of Oxide Films Formed on Metallic Surfaces as Measured Using a Tribological Approach at High Temperature

The surface degradation of metals in boiler tubes and turbines in high-temperature corrosive environments causes severe problems in fuel combustion power plant systems. High-temperature resistant materials have been recently developed using a thermal barrier coating (TBC) and high-chromium alloys. Oxide films or coatings formed on metal surfaces at high temperatures can sometimes decrease the corrosion rate. However, the damage to the material is often accelerated by the mechanical removal of corrosion products from the material surface. It is therefore very important to investigate the mechanical and adhesive properties of the oxide films or coatings on metal surfaces used in high-temperature environments. This paper introduces a tribological method that uses a single spherical projectile impact at high temperature to measure the mechanical and adhesive properties of oxide films formed on various metal surfaces. Impact tests were performed on the surfaces of oxide films after their growth in a high-temperature furnace, and the deformed or fractured surfaces were observed in order to measure the mechanical and adhesive properties. The mechanical and adhesive properties of an elastic modulus, fracture, and exfoliation stresses were measured using the impact method, and the results depended on the type of metal oxide films and on the high-temperature environment.

Tribological approach to study polishing of road surface under traffic

The polishing phenomenon of road pavements under the vehicle traffic constitutes the main mechanism inherent to the loss of skid resistance over time. A better understanding of this phenomenon would allow an improvement of road safety. This study comprises a review of laboratory test and a model simulating the polishing of road surfaces. The laboratory test uses a polishing machine so called 'Wehner–Schulze' which can reproduce the evolution of the road texture from specimens taken directly from road or made in laboratory. The model is based on contact mechanics considerations and considers that the local polishing rate is controlled by the pressure distribution between the car tyre and the road surface. The model evaluates the pressure distribution by taking into account the surface roughness, the applied load and the mechanical properties of the bodies in contact. From the pressure distribution and a proposed wear law, the local roughness evolution of the surface pavement can be readily evaluated. The removal material is proportional to the contact pressure and to the aggregate properties used in roads mix design. The results show that the predicted road profile evolution is consistent with those given by experiments.

Evaluation of water glycol hydraulic fluids: a tribological approach

Water glycol fluids are commonly used as fire-resistant hydraulic fluids, particularly in areas where fires cannot be tolerated, such as foundries, steel mills and mines. However, they have the disadvantage that their wear resistance is unsatisfactory. Hence, there is a need for an additive package which overcomes this poor wear resistance. In order to design an effective water glycol hydraulic fluid for this purpose, four additive packages were considered. The performance of the lubricant composition developed with these packages is studied in detail. The physico-chemical and tribological properties of the formulations were determined using standard methods. The load-carrying properties were studied by four-ball and Timken load methods. The antiwear performance and coefficient of friction were studied by using four-ball and Schwingung Reibung Verschleiss test methods. The topography and surface analysis were carried out using scanning electron microscopy and X-ray photoelectron spectroscopy techniques. Copyright © 2006 John Wiley & Sons, Ltd.

Bulk titanium nitride material obtained from SHS starting powder: Densification, mechanical characterization and tribological approach

Powders used for this study were synthesized by the self-propagating high temperature synthesis (SHS) process. This method allows producing titanium nitride powders in an economic and easy way. Densification of these original powders is carried out by the hot pressing process. Sintering is achieved, under a 50 MPa pressure, at different temperatures (1400 °C, 1600 °C and 1800 °C). At 1600 °C properties are optimised and bulk specimen density is superior to 98%. In addition, microhardness reaches the average value of 1790 ± 225 H V and Young modulus measured is 430 ± 10 GPa. A tribological characterization is then carried out with an adapted four balls machine tribometer. Titanium nitride tribological behavior is compared with the one of other hard materials such as 100C6 steel, titanium carbide and two cemented carbides of different compositions. Parameters such as toughness, hardness and wear volume are correlated in order to understand wear mechanisms origins.

Tribology Approach to the Engineering and Study of Articular Cartilage

Tribology Approach to the Engineering and Study of Articular Cartilage

Tribology Approach to the Engineering and Study of Articular Cartilage

This study has been based on the assumption that articular motion is an important aspect of mechanotransduction in synovial joints. For this reason a new bioreactor concept, able to reproduce joint kinematics more closely, has been designed. The prototype consists of a rotating scaffold and/or cartilage pin, which is pressed onto an orthogonally rotating ball. By oscillating pin and ball in phase difference, elliptical displacement trajectories are generated that are similar to the motion paths occurring in vivo. Simultaneously, dynamic compression may be applied with a linear actuator, while two-step-motors generate the rotation of pin and ball. The whole apparatus is placed in an incubator. The control station is located outside. Preliminary investigations at the gene expression level demonstrated promising results. Compared with free-swelling control and/or simply compression-loaded samples, chondrocyte-seeded scaffolds as well as nasal cartilage explants exposed to interface motion both showed elevated levels of cartilage oligomeric matrix protein mRNA. The final design of the bioreactor will include four individual stations in line, which will facilitate the investigation of motion-initiated effects at the contacting surfaces in more detail.

Tribological approaches for green metal forming

A tribological principle for realizing green metal forming processes is proposed. This principle is based on the adhesion theory of friction. Based on this principle, green metal forming with low friction coefficient may be realized under three kinds of lubrication condition. The present state of the relevant technologies is summarized.

The Influence of Molecular Architecture on the Macroscopic Lubrication Properties of the Brush-Like Co-polyelectrolyte Poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG) Adsorbed on Oxide Surfaces

The co-polymer poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG) has been investigated as a potential biomimetic boundary-lubrication additive for aqueous lubrication systems. In this work, the influence of the co-polymer's architecture on its tribological performance has been investigated. The architectural parameters investigated comprise side-chain (PEG) length, Lys/PEG grafting ratio and backbone chain (PLL) length. The tribological approaches applied in this work include ultra-thin-film interferometry, the mini-traction machine (MTM), and pin-on-disk tribometry. Both an increase in the molecular weight of the PEG side chains and a reduction in the grafting ratio result in an improvement in the lubricating properties of aqueous PLL-g-PEG solution at low speeds. MTM measurements show that an increase in the molecular weight of the PLL backbone results in an increase of the coefficient of friction.

Boundary lubrication of oxide surfaces by Poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG) in aqueous media

In this work, we have explored the application of poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG) as an additive to improve the lubricating properties of water for metal-oxide-based tribo-systems. The adsorption behavior of the polymer onto both silicon oxide and iron oxide has been characterized by optical waveguide lightmode spectroscopy (OWLS). Several tribological approaches, including ultra-thin-film interferometry, the mini traction machine (MTM), and pin-on-disk tribometry, have been employed to characterize the frictional properties of the oxide tribo-systems in various contact regimes. The polymer appears to form a protective layer on the tribological interface in aqueous buffer solution and improves both the load-carrying and boundary-layer-lubrication properties of water.

The frictional interface: a tribological approach of thermal misfit, surface roughness and sliding velocity effects

In ceramic matrix composites, it is now well known that the cyclic fatigue effects are due to a decrease of the stress transfer capability of the fibres that bridge the matrix cracks, because of some wear induced by the seesaw displacements at the interfaces. Therefore, a better knowledge of the cyclic fatigue effects needs a deeper understanding of the microscale mechanisms operating during the friction between fibre and matrix. This is the main subject of the present paper which deals with single filament model composites submitted to push-out tests at room temperature under dry friction condition. Emphasis is placed here on the roughness of the slipping surfaces in relation with thermal misfit, and with sliding velocity.

Rheology and flows of solid third bodies: background and application to an MoS 1.6 coating

After a short background history on solid third bodies, this paper proposes a tribological approach for understanding how a contact takes place when first bodies are in relative movement and are separated by a solid third body. This approach, based on rheology and third body flows, enables friction and wear in contacts “lubricated” by a solid third body to be identified and progressively modelled. Flows and rheology are the two notions used for analysing and structuring dynamic phenomena created by contacts and their interaction with the environment, in the physico-chemical and mechanical sense, i.e. with the ambient atmosphere and the mechanism concerned with the contact, respectively. Due to in-situ instrumentation difficulties, flows are evaluated in relation to those visualised in real time through one transparent first body. Rheology is also evaluated relatively, but by distinguishing the cohesion and ductility of the elements making up the third body that moves in the contact, over a given observation scale. As an illustration, this presentation relies on the behaviour of a contact containing a third body formed in-situ from a coating of MoS 1.6.

The measurement of slipperiness—an international scientific symposium

Occupational slips, trips, and falls (STF) present a tremendous burden on the working people of the world. The precise contribution of slipping to this burden is not completely understood and significant questions exist regarding the definition and measurement of slipperiness. In an attempt to advance slipperiness measurement, a workshop symposium of tribologists, biomechanists, clinicians, engineers, epidemiologists and related scientists was held in order to summarize the state of the science in slipperiness measurement. Organized into issue-focused working groups, participants collaborated on manuscripts addressing conceptual and definitional issues, the contribution of slipperiness to STF injury, and biomechanical, human-centred, and tribological approaches to slipperiness measurement. The conference design, contributions of working groups and outcomes are summarized.

Mechanisms of Post-CMP Cleaning

ABSTRACTWe investigate the post-CMP cleaning process with a tribological approach. A cleaning process involves three components: brush, wafer/disk, fluid undergoing three-body sliding contact between the brush, wafer, and particles from slurry. Having this in mind, we investigated cleaning mechanisms through experimental measurement of friction force and analyzed the contact condition for particle removal. Our investigation leads to the conclusions that the cleaning process is a boundary to elastohydrodynamic lubricating process that involves a constant contact between a brush and the wafer or disk surface. The motion of the brush nodule is such that the surface forces between the brush and workpiece change from an initial adhesion to sliding abrasion. These analysis leads to insight of particle removal mechanisms.

Observation of the floor surface topography changes in pedestrian slip resistance measurements

This study is concerned with the changes of the floor surface topography in the early stage of repetitive wear rubbings and the relationships between slip resistance properties and operationally defined geometric characteristics of the floor surfaces. It was assumed that: (1) alterations in surface topography will be associated with changes in the DFC; and (2) wear process will be accompanied by changes in surface topography. For the analysis of initial characterization on the surface topography, specially prepared, dry and clean metal and perspex specimens were chosen. The surface profiles of the fresh and rubbed flooring specimens were recorded using a laser scanning confocal microscope. From the profile ordinate data read at 1 μm intervals, a number of surface roughness parameters – centre line average, root-mean-square roughness, maximum height, maximum mean peak height, maximum mean depth, and absolute average asperity slope were calculated using a computer program. The skew and the kurtosis of the statistical distribution of each surface profile were also computed. The results indicate that the asperity height and the maximum mean depth were significantly reduced after the friction tests. The average slope of asperities was the parameter that most highly correlated with the dynamic friction coefficient. The analyses also showed that the surface parameters underwent large variations initially, but subsequently these changes were less marked, which was explained by the transition from unsteady-state friction to steady-state friction. These results found that slip resistance properties between the shoes and the floor counterfaces were greatly influenced by the manner in which the geometry of the floor surface was modified. It was suggested that measurement of changes in the surface geometry provides additional information on the analysis of slip resistance and could usefully be reported with friction measurements. Relevance to industry Slipping and falling accidents are a major ergonomic and safety concern in the workplace and the general community. Prevention of slip hazard has focused on designing “slip resistant” footwear and floor surfaces. This study is primarily concerned with the understanding of friction and wear mechanisms from a tribological point of view. A tribological approach may provide additional useful information about slip resistance performance.

New materials in automotive tribology

The rapid, world‐wide spread of automobiles has necessitated the development of improved technologies for environmental protection, resource utilization and customer satisfaction. As the designs of automotive components have changed, emphasis has shifted to tribological approaches. New tribo‐materials are needed for automotive components that must run at higher temperatures and higher [pressure] x.[velocity] conditions. This paper outlines current issues related to tribo‐materials in passenger cars.

Recent Progress in Microtribology. Micro-tribology of Magnetic Recording Disks.

Recording density of magnetic disks has markedly increased as much as 60% a year by decreasing spacing between a magnetic disk and a magnetic head. Micro-tribology is the most significant science and technology to improve mechanical reliability of ultrahigh recording disks. This report will introduce a tribological approach to analyze the phenomena at the interface between the head and the disk.

Tribological testing of traditional road-grading steels leading to the evolution of new road-preparation concepts

In 1983 conventional road-grader steels of major Nordic manufacturers were evaluated in a number of laboratory tests as well as by extensive field testing. The overall conclusion was that there were no significant tribological differences between the tested steel grades. This result inspired a broader tribological approach to the improvement of the economics and performance of road-grading and ice-cutting equipment. This paper presents the technical requirements for the grader blade. It also defines a number of important tribological rules to be obeyed in the design and choice of material for novel grader blades. Finally, a number of new improved tools, meeting these technical requirements and tribological rules are presented. The novel systems have been successfully introduced in the Scandinavian countries. The technological and economic benefits are presented.