Imperial College London

DrShayanSharifi

Faculty of EngineeringDyson School of Design Engineering

Teaching Fellow
 
 
 
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Contact

 

+44 (0)20 7594 9237s.sharifi Website

 
 
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Location

 

Studio 110-12 Prince's GardensSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

5 results found

Rasool G, Sharifi S, Johnstone C, Stack MMet al., 2016, Mapping Synergy of Erosion Mechanisms of Tidal Turbine Composite Materials in Sea Water Conditions, Journal of Bio- and Tribo-Corrosion, Vol: 2, ISSN: 2198-4220

© 2016, The Author(s). Tidal energy, of all marine renewables energy, possesses higher persistency and predictability over long-time scales. Moreover, the higher density of water than air also results in greater power output from a tidal turbine than a wind turbine with similar dimensions. Due to the aggressive marine environment, there are barriers in the development of tidal power generation technology. In particular, with regard to increased rotor diameter, the selection of material presents significant challenges to be addressed including the tribological environment, such as solid particle erosion, cavitation erosion, the effect of high thrust loading on the turbine blade tips and the synergy between sea water conditions and such tribological phenomena. This research focuses on producing and testing a variety of composite materials with different fibres and reinforcement layouts to evaluate two main tribological issues in tidal environments: matrix cutting and reinforcement fracture. A slurry pot test rig was used to measure the effects of different impact angles and particles sizes at constant tip speeds.

JOURNAL ARTICLE

Hayes A, Sharifi S, Stack MM, 2015, Micro-abrasion-corrosion Maps of 316L Stainless Steel in Artificial Saliva, Journal of Bio- and Tribo-Corrosion, Vol: 1, ISSN: 2198-4220

© 2015, Springer International Publishing AG. The role of salivary media is essential during mastication and ingestion processes; yet it can hinder the performance of foreign materials in the oral cavity. The aim of this study was to examine the effects of applied load and applied electrical potential on the tribo-corrosion mechanisms of 316L stainless steel in an environment similar to oral cavity conditions. 316L stainless steel is a material commonly used in dentistry for orthodontic braces, wires and in some cases as dental crowns. This is due to its favourable corrosion resistance. Relatively few studies have examined the materials performance in an oral environment. The results of this work were used to generate polarisation curves and wastage and mechanism maps to describe the material’s tribo-corrosion behaviour. A significant difference in corrosion current densities was observed in the presence of abrasive particles suggesting the removal of the protective chromium oxide passive film. It was found that the corrosion resistant nature of 316L stainless steel resulted in a wear mechanism which was micro-abrasion dominated for all test conditions.

JOURNAL ARTICLE

Holmes D, Sharifi S, Stack MM, 2014, Tribo-corrosion of steel in artificial saliva, Tribology International, Vol: 75, Pages: 80-86, ISSN: 0301-679X

Stainless steel can be used as a dental implant. However, there has been little work on the micro-abrasion of such materials in laboratory simulated oral environments, where abrasion, sliding wear can interact simultaneously. In this study, the effects of applied load, and exposure time were evaluated for a 316 stainless steel in a laboratory simulated artificial saliva. Polarization curves showed an enhancement of corrosion current density with increases in applied load. Wear maps were produced showing wear safety regimes at intermediate loads and exposure times. Possible reasons for such trends are interpreted in terms of the ability of the passive film in providing resistance against third body particle impact and the concentration of particles in the contact at higher loads. © 2014 Elsevier Ltd.

JOURNAL ARTICLE

Sharifi S, Stack MM, 2013, A comparison of the tribological behaviour of Y-TZP in tea and coffee under micro-abrasion conditions, Journal of Physics D: Applied Physics, Vol: 46, ISSN: 0022-3727

The micro-abrasion of Y-TZP, a candidate dental restorative material, was investigated in a range of caffeine-containing solutions which included tea and coffee. Additions of sugar and milk were used to test the effects of viscosity and pH on the wear rate. The results indicated a significant increase in wear rate in the various solutions, with some correlation between wear rate and increases in viscosity and this was linked to enhance particle entrainment in the more viscous solutions. The generally lower wear rate in tea compared to coffee was associated with a longer ageing period in this solution before uniform wear was observed. Micro-abrasion maps were used to characterize the differences in performance for the material in the environments studied. © 2013 IOP Publishing Ltd.

JOURNAL ARTICLE

Sharifi S, Stack MM, Stephen L, Li WL, Wang MCet al., 2013, Micro-abrasion of Y-TZP in tea, Wear, Vol: 297, Pages: 713-721, ISSN: 0043-1648

The objective of this work is to investigate the micro-abrasion of Y-TZP in tea. This material is a candidate replacement in dental restoration and to date there has been very little work carried out to investigate the wear behaviour in oral cavity conditions. Various additions such as milk and sugar, which affect the solution viscosity and pH, were assessed as part of this work and the results were compared to the performance of the material in aqueous conditions. Wear maps were generated showing the change in wear rate as a function of applied load and exposure time. © 2012 Elsevier B.V.

JOURNAL ARTICLE

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