Tribological issues are inevitable since feedstock has up to 93 wt. In this study, each of the relatively soft carbonyl iron powder and the hard, abrasive Iron oxide powder are mixed with binder system, consisting of HDPE High-density polyethylene , Paraffin Wax and S. Stearic Acid at different magnitudes of volumetric powder loading. The properties of the feedstocks made from the two materials showed significant variation in flow behaviour due to difference in inter-particle frictional behaviour with changing process parameters as well as material parameters.
Furthermore, to study flow behaviour of feedstocks apparent viscosity is plotted against temperature and shear rate in order to establish the sensitivity of temperature and pressure. Flow behaviour index was determined by analysing variation of viscosity with shear rate of feedstock.
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As expected, results show that the feedstock having iron oxide powder with hard irregular shaped particles exhibits a higher viscosity if compared to the spherical particles in the Carbonyl iron powder feedstock. It was observed that the feedstock containing iron oxide powder 75 wt.
Additions of graphite powder to the hard and abrasive iron oxide powder to facilitate reduction of the iron oxide during sintering would also be expected to improve the flow behaviour of the iron oxide feedstock on account of the superior lubricating properties of the graphite powder. Copyright of Advanced Materials Research is the property of Trans Tech Publications, Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission.
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This task is complicated and requires theoretical analysis. Alexeyev and Jahanmir45 have attempted to develop self lubrication theory based on quantitative analysis. Slip-line field analysis of plastic deformation is used to analyze the processes of deformation and flow of the soft phase toward the sliding surface.
They found a general relationship for deformation and flow of soft phase is obtained. It shows that the properties as well as size and shape of hard matrix and soft second-phase particles control the processes of deformation and flow of the soft phase as shown in Fig. Solid lubrication is introduced from the solid lubricant cavities reservoirs dispersed within the material. The solid lubricant particles deform by the sliding action of the mating surface and are squeezed out toward the surface, forming a soft interfacial film. The presence of this film is believed to be responsible forthe observed low friction and reduced wear.
When the solid lubricant film is worn away, the resulting increase in friction accentuates plastic deformation of the surface layer and forces more material from second-phase particles toward the surface, thus re-forming the worn film. The beneficial effect of selflubrication depends on the thickness of the film, the relative plastic properties of the film and the sublayer, and the pressure experienced by the soft film and sublayer Very few studies have been done on the processes of film formation and destruction.
In order to understand the tribological behaviour of metal matrix selflubricating composite, the basic mechanism of the formation of lubricating films must be developed. The early studies of wear behaviour on self-lubricating aluminium composite using graphite as solid lubricant have been done by several researchers.
They found that the reduction in friction and wear of the aluminium-graphite composites is result of the embedded graphite particles during sliding, forming a lubricating film on both the tribosurface of the composite and the steel mating surface. Whereas, Alexeyev and Jahanmir47 attempted to describe the process of film formation in self-lubricating composites and deformation of the film based on quantitative analysis by the slip-line field method.
The results show that the size of second-phase particles in the composite, the relative shear yield limit of the matrix and the soft phase, and the thickness of the film control the tribological performance of these composites. They found that the tribological behaviour of the composite depends on the hardness of the matrix, the rate of release graphite particulates, the structure of the solid lubricating film deposited on the wearing material, and the structure of Al chip clusters.
Development of five wear theory might be summarized as shown in Fig. However, in , Sanino and Rack51 proposed the theory based on debris generation in order to shows the wear mechanism in integrated manner. They stated that wear debris generation mechanism is the consequence of a combination of subsurface, surface and third body dynamic behaviours.
Based on literatures, since year , there are some research focuses on the role of soft reinforcement particle in hybrid composite. The soft reinforcement likes graphite and carbon fibre, whereas the hard material likes Saffil fibre or SiC particles in hybrid composite. Some researchers have studied the sliding wear behaviour of aluminium hybrid composite found that the hybrid composite showed the best performance in wear resistance. Their result showed more stable tribo-layers on the contact surfaces of the graphitic composites compared to non-graphitic composites However, the hard constituents in the tribo-layers were the scuffing damage that they inflicted on the counterface.
Therefore, based on previous work on dry sliding wear of multiple reinforcement composite, it might be proposed that the wear mechanism involved in integrated wear mechanism as shown in Fig. It can be concluded as follow: Adhesive wear is influenced by critical parameters such as applied load, speed and environment. Abrasive theory is influenced by contact geometry, matrix and hard reinforcement phase as well as interface characteristics.
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Self lubrication theory is influenced by the smearing of soft reinforcement phase on the contact surfaces during sliding process. Hutchings IM. Tribology: Friction and Wear of Engineering Materials. Butterworth-Heinemann Chawla N, Chawla KK. Metal Matrix Composites. Springer Science Business Media, Inc. Abrasive wear mechanisms and the grit size effect. Wear ; Resistance to abrasive wear and the hardness of metals in Russian , Dokl.
Nauk SSSR ; An experimental study of friction and wear durin abrasion of metals, Proc. London ; Ser. A, New features of the abrasion process shown by soft metals; the nature of mechanical polishing, J. Applied Phys.
The abrasion of metals: a model of the process. Wear ; 5: Larsen-Basse J. Influence of grit diameter and specimen size on wearduring sliding sliding abrasion. Zum Gahr KH. Microstructure and wear of materials, Elsevier, Amsterdam , p. Miki H, Kobayashi S. An equation for the centre-line average roughness of material slide against abrasive paper.
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Modi OP. Two-body abrasion of a cast Al-Cu Al alloy-Al2O3 particle composite: influence of heat treatment and abrasion test parameters. Jahanmir S, Suh NP. Mechanics of subsurface void nucleation in delamination wear. Wear a; Argon AS. Formation of cavities from nondeformable second-phase particles in low temperature ductile fracture. ASME, Ser. Alpas AT, Zhang J. Effect of SiC particulate reinforcement on the dry sliding wear of aluminium-silicon alloys A Wear behavior and microstructural changes of SiCw-Al-Al composite under unlubricated sliding friction.
Venkataraman B, Sundarajan G. The sliding wear behaviour of AlSiC particulate composites-II, The characterization of subsurface deformation and correlation with wear behaviour. Acta Mater. Sliding wear and transfer. Oxidative wear aluminium-silicon alloys. Foundryman ; Subramaniam C. On mechanical mixing during dry sliding of aluminium Sliding wear behavior of SiC whisker-reinforced aluminum composite. Microstructural characterization of mechanically mixed layer and wear debris in sliding wear of an Al alloy and an Al based composite.
Dry sliding wear of aluminium composite-a review. Composite Science and Technology ; Bowden FP, Tabor D. Oxford University Press, Oxford Friction and wear of aluminum-graphite composites: the smearing process of graphite during sliding. Alexeyex N, Jahanmir S. Mechanics of friction in selflubricating composite materials II: Deformation of the interfacial film. Wear b; Wear of cast Al-Si alloys containing graphite. Microstructure and wear of cast Al-Si alloy graphite composites.
TRIBOLOGY AND DEVELOPMENT OF WEAR THEORY: REVIEW AND DISCUSSION
Sintered aluminum alloy-solid lubricant particle composites: sliding wear and mechanisms of lubrication. Goto H, Uchijo K. Wear mechanism of Al-Si alloy impregnated graphite composite under dry sliding. Dry sliding wear of discontinuously reinforced aluminium composites: review and discussion. Wear ; : The role of tribo-layers on the sliding wear behavior of graphitic aluminium matrix composites.
Dry sliding friction and wear properties of Al2O3 and carbon short fibres reinforced AlSi alloy hybrid composites. Influence of sliding speed on the dry sliding wear behaviour and the subsurface deformation on hybrid metal matrix composite. Effects of reinforcement content and ageing duration on wear characteristics of Al based hybrid composites. Naplocha K, Granat K.
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Suresha S, Sridhara BK. Effect of addition of graghite particulates on the wear behaviour in aluminiumsilicon carbide-graphite composites. Materials and Design ; 31 4 : Effect of silicon carbide particulates on wear resistance of graphitic aluminium matrix composites. Materials and Design ; 31 9 : All received manuscripts have to pass through "Plagiarism Detection Software" test before forwarding for peer review. We consider "Plagiarism is a crime". IJCRR can not be held responsible for views, opinions and written statements of researchers published in this journal.
hireasset.com/tyxec-cell-phone.php Self Lubrication Theory Apart from hard second-phases particle in soft matrix composite, a soft secondphase particles in hard and strong matrix composites are widely used in sliding bearing applications. They found that the tribological behaviour of the composite depends on the hardness of the matrix, the rate of release graphite particulates, the structure of the solid lubricating film deposited on the wearing material, and the structure of Al chip clusters General discussion Development of five wear theory might be summarized as shown in Fig. Stachowiak GW. Wear: Materials, Mechanisms and Practice.
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