The sliding wear behaviour of AlSiC particulate composites—II. The characterization of subsurface deformation and correlation with wear behaviour
TL;DR: In this paper, a detailed examination of the subsurface regions beneath the worn surface and the debris was carried out to provide a deeper understanding of the wear behavior of Al-SiC particulate composites.
Abstract: The purpose of this paper is to provide a deeper understanding of the wear behaviour of AlSiC particulate composites through a detailed examination of the subsurface regions beneath the worn surface and the debris. Such an examination indicates that the subsurface deformed layer beneath the worn surfaces of Al-MMC pins is composed of a number of distinct layers like the mechanically mixed layer (MML), the shear deformed and bulk deformed layers. The MML is absent in Al samples. The thickness of each of these layers is dependent on both the volume fraction of SiC and the test load. Within the shear deformed layer, the presence of a soft shear sub-layer wherein the flow stress decreases with increasing shear strain has been established in all the MMC pins and at both the test loads. The hardness of MML is about six times the bulk hardness of Al-MMC. Electron probe microanalysis of both the MML layer and the wear debris indicates the presence of a substantial level of iron, transferred from the disc material. The debris size is of the order of millimetres at higher load while at the lower load, it is of the order of a few hundred micrometres. On the basis of the above experimental observations, the sequence of micromechanical events which lead to the generation of wear debris has been surmised.
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TL;DR: In this article, the influence of applied load, sliding speed, wearing surface hardness, reinforcement fracture toughness and morphology are critical parameters in relation to the wear regime encountered by the material.
Abstract: Aluminium-silicon alloys and aluminium-based metalmatrix composites have found application in the manufacture of various automotive engine components such as cylinder blocks, pistons and piston insert rings where adhesive wear (or dry sliding wear) is a predominant process. Materials possessing high wear resistance (under dry sliding conditions) are associated with a stable tribolayer on the wearing surface and the formation of fine equiaxed wear debris. For adhesive wear, the influence of applied load, sliding speed, wearing surface hardness, reinforcement fracture toughness and morphology are critical parameters in relation to the wear regime encountered by the material. In this review contemporary wear theories, issues related to counterface wear, and wear mechanisms are discussed. Other areas of research relevant to adhesive wear of AlSi alloys and aluminium composites containing discontinuous reinforcement phases, such as the role of the reinforcement phase, are also presented.
519 citations
TL;DR: In this article, the sliding friction and wear behavior of Al, Al-7075 and SiC particulate reinforced aluminium matrix composites (Al-SiC) were investigated under dry sliding wear conditions.
Abstract: The sliding friction and wear behaviour of aluminium (Al), aluminium alloy 7075 (Al-7075) and SiC particulate reinforced aluminium matrix composites (Al-SiC) have been investigated under dry sliding wear conditions. The wear tests were carried out at a sliding speed of 1 m/s and at normal load ranging up to 220 N. The overall objective of the study is to improve our current understanding with regard to the influence of mechanically mixed layers (MML), which form on the surface of the wearing material during the course of the wear test, on the friction and wear behaviour. The aluminium alloy 7075 was used in both solution treated and aged conditions. The aluminium based metal matrix composites studied contained 10 and 40 vol.% of SiC particles as the reinforcing phase. A detailed characterisation of the MML was carried out using SEM, EPMA and microhardness testing in order to understand the influence of test material and load on the composition, hardness and thickness of the MML formed and in turn the influence of the MML on the friction and wear behaviour. On the basis of the above characterisation, it is demonstrated that the observed friction and wear behaviour of Al, Al-7075 alloy and Al-SiC can be best understood in terms of the formation and fracture rate of the MML rather than the bulk properties of the material.
323 citations
Cites background from "The sliding wear behaviour of AlSiC..."
...Recently, we have reported [13,14] the friction and wear behaviour of Al-SiC composites with the volume fraction of SiC particulate ranging from 10 to 40%....
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...[14])....
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...Compelling evidence was also provided in the above study [13,14] to conclude that the formation of the MML was caused by turbulent plastic flow induced by the onset of shear instability at a critical depth below the wearing surface....
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TL;DR: In this paper, an Al-7Si alloy reinforced with in situ TiB 2 particles was synthesized successfully by using salt reaction route and the in situ composites have shown significant improvement in mechanical properties in comparison to the base alloy.
Abstract: Al-7Si alloy reinforced with in situ TiB 2 particles was synthesized successfully by using salt reaction route. These in situ composites have shown significant improvement in mechanical properties in comparison to the base alloy. The wear resistance of the alloy also significantly improved with the addition of TiB 2 particles. The hardness, strength and wear resistance increased with increasing TiB 2 content of the composites. TiB 2 appears to not only act as a grain refiner for primary α-Al but also as a modifier of Si in eutectic mixture. The mechanical properties of the present Al-Si/TiB 2 composites are better than those reported earlier with SiC reinforcement. Analysis of the worn surface of Al-Si/TiB 2 composites tested under normal loads of 40 and 120 N suggests that adhesion and ploughing are predominant at lower loads and delamination is predominant at higher loads.
282 citations
TL;DR: In this paper, the dry sliding wear behavior of the Ti-6Al-4V alloy sliding against itself and AISI M2 steel was investigated at different sliding velocities (between 0.3 and 0.8 m/s).
Abstract: The dry sliding wear behaviour of the Ti–6Al–4V alloy sliding against itself and AISI M2 steel was investigated at different sliding velocities (between 0.3 and 0.8 m/s) and applied loads (between 50 and 200 N). Two wear mechanisms were identified, irrespective of the counterface and applied load: oxidation wear at the lowest sliding velocities (0.3–0.5 m/s) and delamination wear at the highest (0.6–0.8 m/s). Wear rate was higher against the AISI M2 at the lowest sliding velocities, and it continuously decreased as sliding velocity was increased. On the other hand, as the sliding velocity was increased it first decreased, experienced a minimum and then became very severe in the case of sliding against the Ti–6Al–4V alloy. This behaviour was explained by making reference to the effect of the counterface. At the lowest sliding velocities, the AISI M2 counterface exerted an abrasive effect on the Ti–6Al–4V alloy, thus accelerating its oxidative wear. At the highest sliding velocities, metallic delamination (which developed through the formation of a mechanically mixed layer (MML) on the surface) was the controlling wear mechanism and the thermal effects connected with the frictional heating became of primary importance. Thus, as surface temperature increased (due to an increase in load or a decrease in the thermal conductivity of the counterface, i.e., in passing from the Ti–6Al–4V counterface to the AISI M2) the plastic strain rate at the contacting asperities also increased (by reversible dislocation motion) and wear rate also increased, in accordance with the theory of delamination.
230 citations
TL;DR: In this article, the micro-structural properties of mechanically mixed layers and wear debris formed during sliding wear of an Al-Si alloy and an AlSi/SiCp metal matrix composite against M2 tool steel under dry sliding conditions were investigated using scanning electron microscopy (SEM), TEM with energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) as well as Mossbauer spectroscope.
Abstract: The present work was undertaken to characterize mechanically mixed layers (MML) and wear debris formed during sliding wear of an Al-Si alloy and an Al-Si/SiCp metal matrix composite against M2 tool steel under dry sliding conditions. In particular, chemical, microstructural and crystallographic characteristics of the MMLs and wear debris have been investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM) with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), as well as Mossbauer spectroscopy. It was observed that MMLs were formed in the worn surfaces at a variety of sliding loads used in the present work. The results show that the mixed layers and wear debris generated from the sliding systems had similar microstructural features and were comprised of a mixture of ultrafine grained structures, in which the constituents varied depending on the sliding loads. At a low load, the ultrafine structures mainly consisted of the original base materials, i.e. α-Al solid solution and α-Fe from the steel. With an increase in sliding load, the ultrafine structures were incorporated with an Fe-Al(Si) intermetallic compound and an aluminum oxide. The formation mechanisms of the mechanically mixed layers and their influences on wear mechanisms of these multiphase materials were also studied on the basis of the microstructural observations.
186 citations
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TL;DR: The potential of wear-Mechanism diagrams is explored in this paper, where the rate and the regime of dominance of dry wear mechanisms are investigated empirically and by modelling by theoretical analysis calibrated to experiment.
Abstract: The potential of Wear-Mechanism Diagrams is explored. Diagrams which show the rate and the regime of dominance of each of a number of mechanisms of dry wear (delamination, mild and severe oxidation, melting, seizure, etc.) are constructed empirically (that is, from experimental data alone) and by modelling (by theoretical analysis calibrated to experiment). The method is applied to steels, and has wider application as a way of classifying and ordering wear data, and of showing the relationships between competing wear mechanisms.
961 citations
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01 Jan 1986
TL;DR: In this article, an Introduction to Microstructures Processing and Design International Series on Materials Science and Technology (ISIMS) 3 by D.R.H. Jones is presented.
Abstract: Engineering Materials 2 An Introduction To Microstructures Processing And Design International Series On Materials Science And Technology V 2 [Free] Engineering Materials 2 An Introduction To Microstructures Processing And Design International Series On Materials Science And Technology V 2 [EPUB] [PDF] Buy Engineering Materials 2: An Introduction to Microstructures, Processing and Design: v. 2 (International Series on Materials Science and Technology) 3 by D.R.H ... za, 27 apr 2019 09:02:00 GMT Engineering Materials 2 ???? Engineering Materials 2 Fourth Edition An Introduction to Microstructures and Processing Internation Amazon.com: Engineering Materials 2: An Introduction to ... Amazon.com: Engineering Materials 2: An Introduction to Microstructures, Processing and Design (International Series on Materials Science and Technology) (v. 2 ... Engineering Materials 2 An Introduction To Microstructures ... Download Books Engineering Materials 2 An Introduction To Microstructures Processing And Design International Series On Materials Science And Technology V 2 , ... Engineering Materials 2 (4th ed.) by David R. H. Jones (ebook) Engineering Materials 2: An Introduction to Microstructures and Processing (4th ed.) (International Series on Materials Science and Technology series) by David R. H ... PDF Engineering Materials 2 An Introduction To ... Title: PDF Engineering Materials 2 An Introduction To Microstructures Processing And Design International Series On Materials Science And Technology V 2 Materials Science and Engineering: A Journal Elsevier Materials Science and Engineering A provides an international medium for the publication of theoretical and experimental studies related to the... 0080325327 Engineering Materials 2: an Introduction to ... Engineering Materials 2: An Introduction to Microstructures, Processing and Design (International Series on Materials Science and Technology) (v. 2) by Ashby, Michael ...
403 citations
TL;DR: In this article, a new model for the source of friction during the steady-state sliding of metals is described, focusing on the plastic work done in the near-surface region, described in terms of work hardening, recovery and the microstructure existing during steady state sliding.
Abstract: Most theories of sliding friction have emphasized surface roughness or adhesion. In some cases plastic deformation has been invoked to account for energy dissipation. After a brief review of published explanations of friction, a new model is described for the source of friction during the steady state sliding of metals. It focuses on the plastic work done in the near-surface region, described in terms of work hardening, recovery and the microstructure existing during steady state sliding. The model is discussed with respect to several alternate ways in which plastic deformation has been incorporated in recent theories of friction. Reasonable results are found when the new model is used to estimate friction coefficients for metals. Also, the model appears to be consistent with a number of published observations on the relation of friction to load, sliding distance, surface temperature and microstructure, and with a model for sliding wear which has been presented earlier.
310 citations
TL;DR: In this article, simplified diagrams are constructed for E.T.P. copper, α-brass, two steels and an aluminium alloy, which show how fracture mechanism changes with stress state and help rationalize a number of apparently conflicting observations.
Abstract: Diagrams can be constructed in stress space which show, for metals and alloys, the competition between the processes which lead to fracture. These include yield, necking, void nucleation, ductile fracture, brittle grain-boundary fracture, cleavage, shear fracture, and plastic rupture. Simplified diagrams are constructed for E.T.P. copper, α-brass, two steels and an aluminium alloy. The diagrams show how the fracture mechanism changes with stress state and help rationalize a number of apparently conflicting observations. They have application in predicting the behaviour of metals under complex stress states.
113 citations
TL;DR: In this article, a model is derived to analyze the conditions under which flat pieces of wear debris are formed by ductile metals during sliding wear, and it is shown that shear occurs preferentially below the surface.
Abstract: A model is derived to analyze the conditions under which flat pieces of wear debris are formed by ductile metals during sliding wear. The model assumes that the wear piece contains local planar regions of metal that are more prone to yield than the surrounding material. It is shown that shear occurs preferentially below the surface. Increasing the load leads to the critical condition for shear being satisfied throughout an increasingly wider band of material. At the same time the driving force on the shear plane approaches an asymptotic limit as the load increases.
70 citations