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After a review on tribologically transformed structures (TTSs), TTS nucleation during fretting wear tests is discussed for different experimental conditions. A ball-on-flat contact was used for testing. Through metallographical examinations, parameters were proposed to predict the zones where TTS nucleation is favoured, and to understand better the initiation mechanisms.
A multidisciplinary approach to wear simulation to investigate rolling-sliding abrasion is described. Wear is a stochastic process where fatigue combines with abrasion, adhesion and corrosion. Statistical methods were found to be highly suitable for conceiving and analysing laboratory simulation of the wear process. A special procedure of so-called two-level complex design of experiments is described...
The rolling contact fatigue and wear characteristics of uncoated and diamond-like carbon coated VIM-VAR M50 bearing steel were investigated at room temperature and 177°C (350°F) and a Hertzian stress level of 4.8 GPa (700 ksi). The coatings were deposited via ion beam enhanced deposition and were approximately 33 nm thick. Rolling fatigue and wear tests were conducted using a ball-on-rod type tester...
The present study systematically investigates the effect of airborne contaminants on the magnetic head wear of a helical scan videotape recorder (VTR). Experiments were performed to investigate the internal wear particle generation, and the effect of airborne contaminants on the head wear and signal error rates. The flow held around the scanner was also studied numerically. Particle concentrations...
A laser surface modification technique can be used as a part of a dublex treatment process to improve the surface properties of Ti-6Al-4V alloy. The present study is conducted to investigate the surface properties of the Ti-6Al-4V alloy due to laser melting prior to a plasma nitriding process. Consequently, nitriding is carried out to obtain the depth of the nitride zone of 30 μm. A CO 2 laser...
In conventional pin-on-disk testing of the tribological characteristics of two different materials in sliding contact, the main parameters of interest are notably the friction and wear properties of the material pair. However, when two bodies consisting of hard and soft materials respectively are subjected to such testing, the appearance of a transfer film, or third body which can be a composite mixture...
In the present paper an experimental investigation has been carried out on the steady state and dynamic performance characteristics of a tilting pad journal bearing. Pad temperature and oil temperature measurements have been made using a thermocouple measuring system. Coast down time experiments were conducted on a rotor bearing test rig, and the coefficient of friction of tilting pad journal bearing...
Wear debris in the form of thin platelets is observed in wear of sliding, rolling and eroding components. The paper discusses two mechanisms in which such platelets can be generated: (i) extrusion of material from below the contact into thin slivers which subsequently break off to provide lamellar wear debris, and (ii) fracture of a thin layer leading to delamination wear debris. Both these mechanisms...
Ceramic coatings have been proven to be a good choice for preventing the base material from wear, corrosion, erosion and other unfavourable damage. In the field of thin solid films (< 10 μm), titanium nitride (TiN) is still the most widely accepted in engineering applications. Over the last years, chromium-base (Cr-base) coated tools have come onto the market. Consequently, deeper knowledge of...
This paper represents a new concept to be used in journal bearings. A chamfer is machined circumferentially at both sides of the bearing inner surface, thus minimizing or almost preventing the side-leakage flow rate in lightly loaded journal bearings. This new concept eliminates the need for sealing and collecting this leakage. The circumferential flow is found to be sufficient to achieve cooling...
The rolling contact fatigue (RCF) behaviour of thermally sprayed WC-Co coatings with nominal compositions of WC-12%Co, WC-10%Co-4%Cr and WC-17%Co was studied with a two-roll configuration roll-against-roll testing apparatus under 420-600 MPa Hertzian contact stresses in unlubricated pure rolling conditions. The coatings were prepared by atmospheric plasma spray (APS) and two high-velocity oxyfuel...
The wear behaviour of Cr12MoV, 65Nb and GCr15 steels coated with VC and quenched without the coating was investigated. The wear tests were performed using a pin-on-disc wear machine under dry sliding conditions. The microstructure of the coating was characterized using Neophot-21 optical microscopy and X-ray diffractometry (XRD). The surface and subsurface changes that took place during wear were...
The automation and optimization of the manufacturing process play an important role in improving productivity. For this, monitoring and diagnostic systems are becoming increasingly necessary in manufacturing. This paper describes an indirect technique for monitoring cutting tool conditions. An attempt is made here to extract maximum information from acoustic emission (AE) signals acquired during machining...
A multilayer paint erosion indication technique to produce a highly visual and accelerated map of erosion damage occurring in a three-dimensional component model has been developed. An investigation to obtain an understanding of how the paint layers eroded as a function of a number of erosion variables was performed. It was observed that the erosion rate behaviour of paint layers as a function of...
Precision hard turning provides an alternative to grinding in some finishing applications. Rapid tool wear, however, remains an impediment to the process being economically viable. This experimental study investigates microstructural aspects of cubic boron nitride (CBN) tool wear in finish hard turning. Results indicate the following: (1) carbide sizes of the workpiece have significant effects on...
Empirical wear transition maps have been constructed to delineate the load velocity conditions under which wear transitions occurred in an A356 Al alloy and an A356 Al-20%SiC composite. Experiments were performed in dry sliding conditions, using a block-on-ring (SAE 52100) configuration, within a load range of 0.2-400 N and a sliding velocity range of 0.2-5.0 m s -1 . Both materials displayed...
In this study, the hardness, fracture toughness, and abrasive wear behavior of three zirconia-toughened MoSi 2 composites and a zirconia-toughened Al 2 O 3 were examined and compared with similar materials containing no zirconia second phases. Each of the composites contained 20 vol.% ZrO 2 ; however, the polymorph of the added zirconia particles was varied to give...
We describe a set of wear tests in which machined surfaces were produced by single point face milling of an aluminium alloy. The objectives were firstly to identify surface characteristics associated with tool chipping, and secondly to demonstrate that a fibre optic surface profiling probe capable of in-situ operation on the machine tool had the ability to provide the same wear information as a metrological...
The tribological experiments under circumstances of hydrodynamic and elastohydrodynamic lubrication, the immersion test in lubricating oil as well as the exposure test to the environment have been performed to elucidate the effect of hydrogen on soft and hardened surface layers. The occurrence of the effect of hydrogen tribosorption in lubricated frictional nodes has been confirmed. This effect proceeds...
Friction and wear tests of pure polymers, polytetrafluoroethylene (PTFE), nylon 6, and polymethyl methacrylate (PMMA), vs. stainless steel were carried out on an MM200 tester. The XPS spectra and the atomic relative concentrations of elements on friction surfaces of stainless steel were analysed. The ESR spectra of radicals in polymer wear debris were determined. The results indicate that complex...
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