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In this study polyphosphate lubricant was introduced into steel rolling process. The friction coefficient reduced from 0.463 to 0.238 by the presence of polyphosphate lubricant as compared with unlubricated condition, calculated from 2-high Hille 100 rolling mill tests. A tribofilm of ~100nm can be observed on the strip surface, greatly improving the surface finish. This tribofilm well adhered on...
Elevated temperature sliding contact experiments were carried out on an Al–Mg alloy AA5083 to study the formation of oxide fibres on their surface. Deformation and friction tests were conducted at a constant strain rate of 4×10−2s−1 at temperatures 350°C, 450°C and 545°C. The samples were tested in two surface conditions, namely in the as-received condition, with surfaces covered with a tribolayer...
In rolling contact bearings, contact occurs between the rolling surfaces over a small region. Hence, high contact stresses are induced in the region even under a small load. These stresses are cyclic in nature. Over a long period of time, the surface gets fatigued and surface fatigue wear ensues. The experimental investigation carried out in the laboratory earlier consumed a long time. Therefore,...
The incentive is strong for optimising sliding materials to reduce the risk for scuffing. In this study, scuffing tests were performed aiming towards finding new piston ring materials for greener marine diesel engines and also towards understanding scuffing mechanisms better. The tested ring materials where grey iron, Stellite 6, plasma sprayed cermet and high velocity oxy fuel (HVOF) cermet (both...
This work focussed on assessing the contact conditions driving the adhesion tendency of PVD TiAlN coated cemented carbide during reciprocating sliding against a normalized AISI 4137 carbon steel. A special emphasis is given to the surface topography of the coating. Results are analysed in terms of friction and material transfer over a large range of temperatures (up to 800°C) and contact pressures...
Si added DLC coatings may be of value for engineering applications where a low COF and high wear resistance are required for the extended service life, during which the operating temperatures may increase above 200 °C. Hot/warm forming dies, machining tools, or critical sliding components such as the upper compression rings in combustion engines are among the components that operate under demanding...
Superior tribological properties of nano-lubricants in boundary/thin film lubrication are well established for mineral oils. However, in view of the environmental aspects, nano-lubricants developed from vegetable oils are more preferable and studies are to be carried out to evaluate the performance of vegetable oils when nanoparticles are added to them. In this paper, tribological properties of nano-lubricants...
This paper presents results of testing carried out to assess the wear and RCF performance of laser clad rail. Stronger and harder materials can be laser clad on top of the working surfaces of standard (e.g. 260 grade) rail in order to improve wear and RCF life. A twin-disc method has been used to assess the suitability of various candidate cladding materials. The materials were clad on top of 260...
The improvements in camera technologies and image processing have caused full field measurement techniques to become more and more frequently used in the field of experimental mechanics. Nevertheless, few applications can be found in the field of contact mechanics. Therefore, the aim of this work is to present, a novel experimental set-up based on coupled kinematic–thermal measurements used for the...
This study is intended to produce reliable quantitative information about adhesive wear phenomena of metallic materials in the early stage of dry sliding. The outcome of this study will contribute to the refinement of the physical model of a wear mechanism. A devised technical method was employed in the study to enable data acquisition linked with the position of measurement on the specimen and objective...
This paper describes the friction and wear behavior of a Co–Cr alloy sliding on a Ta–W alloy. Measurements were performed in a pin-on-flat configuration with a hemispherically tipped Co-base alloy pin sliding on a Ta–W alloy flat from ambient to 430°C. Focused ion beam-scanning electron microscopy (FIB-SEM) and cross-sectional transmission electron microscopy (TEM) were used to identify the friction-induced...
Adhesion and, in particular, the transfer of aluminium alloys to the bearing surface of a die are two of the main reasons for tool failure and the poor surface quality of products, especially at elevated temperatures. The present work was focused on the EN-AW6060 aluminium alloy׳s transfer initiation and the evolution to an AISI H13 hot-work tool steel, as well as CrN and TiAlN coatings in a cross-cylinder,...
The scratch resistance of thin brittle coatings deposited on rigid substrates with a soft intermediate layer has been characterized by instrumented nanoscratch testing in order to identify the damage mechanisms. Several “hard thin film/polymer/rigid substrate” multilayers have been addressed with varying compositions and thicknesses. The relevance of the use of nanoscratch with respect to end-user...
The main focus of current research in non-asbestos organic (NAO) friction materials (FMs) is on searching replacement of copper which is a recently proven hazard to the aquatic life. Cu is almost invariably used in the various forms in FMs mainly because it enhances thermal conductivity of a composite which helps to dissipate frictional heat efficiently from the friction surface and thus resists the...
This present test evaluates wear resistance of overlay welded High Chromium White Iron (HCWI) in comparison with quenched and tempered low alloyed carbon steels within a hardness range between 400 and 700HBW. The HCWI overlay material had a carbon content in the range of 3–5% and a chromium content of 20–25%. The wear performance was evaluated by the use of two different sizes of granite rocks. This...
The wear resistance of coatings is a very important factor which not only influences the reliability but also the lifetime of electrical connectors. The coefficient of friction of the coating, along with the normal force of the contacts, determines the insertion and extraction force of connectors and in addition represents an important indicator for the state of the contact surfaces.The main finding...
Cobalt-based superalloys are used in aero-engine combustor components due to their high strength and wear resistance at elevated temperatures. The objective of this investigation is to study the role of the surface oxide formed during the fretting process on the tribological behavior of this class of materials, at temperatures up to 550°C. The investigation, which was carried out using a specially...
This work analyses the wear resistance under dry sliding conditions by the pin-on-ring method of an austempered ductile iron (ADI) micro-alloyed with different amounts of boron. The main observed effect of boron was to accelerate the transformation of austenite to ausferrite during the austempering heat treatment; this caused lower values of retained austenite in the irons with boron additions. Lower...
The aim of this study is to investigate the influence of laser cladding Fe-based alloy on microstructure and wear characteristic of wheel/rail materials using a rolling–sliding wear testing apparatus. Especially, the effect of lanthanum oxide on the properties of laser cladding coating was explored in detail. The results show that the laser cladding Fe-based alloy coating consists of dendrites and...
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