Author
S. Nayak
Bio: S. Nayak is an academic researcher from University of Tennessee. The author has contributed to research in topics: Microstructure & Coating. The author has an hindex of 7, co-authored 10 publications receiving 268 citations.
Papers
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TL;DR: A review of engineering coating for engine application is presented in this article, where issues relating to dimensional stability, tribological properties, lubrication, coefficient of friction, hot hardness, amenability for honing, surface roughness and topography, residual stress, adherence, damage tolerance and resistance, pores density and conditions and cost performance are discussed.
Abstract: In this paper, a review of engineering coating for engine application is presented. Issues relating to dimensional stability, tribological properties, lubrication, coefficient of friction, hot hardness, amenability for honing, surface roughness and topography, residual stress, adherence, damage tolerance and resistance, pores density and conditions and cost performance are discussed. There exist advantages and limitations of conventional materials systems and techniques such as chemical-vapor-deposited diamond-like carbon (DLC) coating, plasma sprayed metal matrix composite coating, tribologically functional ceramic coatings, etc. Nano-grains of a crystalline phase hold promise to solve several such problems present in conventional coatings. In addition, surface-related problems are addressed for high performance engines and hydrogen powered automotive engines.
117 citations
TL;DR: In this article, an attempt has been made to explore deposition of Fe-based amorphous/glassy layer on a plain carbon (AISI 1010) steel by laser surface cladding (LSC) to improve resistance of the substrate to wear and corrosion.
Abstract: In the present study, an attempt has been made to explore deposition of Fe-based amorphous/glassy layer on a plain carbon (AISI 1010) steel by laser surface cladding (LSC) to improve resistance of the substrate to wear and corrosion. Three known glass forming powder blends (under rapid solidification condition) with nominal compositions of 94Fe4B2C, 75Fe15B10Si and 78Fe10BC9Si2Al1C (all in wt.%) were deposited by LSC using a continuous wave Nd:YAG laser under optimum processing conditions determined by preliminary trials. Following LSC, the microstructure and mechanical properties (microhardness and wear resistance) were evaluated in details. Despite the rapid quenching accompanying LSC, none of the coatings developed/retained amorphous/glassy cladding possibly due to large-scale solute redistribution in the clad zone and/or between the clad layer and substrate. The clad microstructure is characterized by fine dispersion of nano/microcrystalline intermetallic and interstitial compounds/phases in ferritic matrix. Both microhardness and wear resistance showed a significant improvement, particularly after LSC with 94Fe4B2C. Potentiodynamic polarization studies in 3.56 wt.% NaCl solution showed that corrosion resistance of the substrate was remarkably improved by LSC with 94Fe4B2C, but slightly deteriorated after LSC with the other two coatings. Thus, it appears that LSC with 94Fe4B2C, among the present coatings, significantly enhances hardness and resistance to wear and corrosion of the substrate, though fails to develop/retain amorphous microstructure under the present laser processing condition.
96 citations
TL;DR: In this article, Li et al. used laser surface engineering (LSE) to obtain a refined microstructure compared to the cast substrate structure of A319 Al alloy for car engine cylinders.
Abstract: Cast A319 Al alloy, which is a popular choice for automobile engine cylinder block material, has been limited in that use by its poor tribological properties. Various techniques have been explored to address this problem, including the one addressed in this study, laser surface engineering (LSE.) Engine cylinders made of A319 Al alloy were LSE coated with FeO. The region of coating produced a refined microstructure compared to the cast substrate structure. Also, the FeO coating displayed superior wear performance compared to uncoated A319 Al under dry sliding wear conditions.
14 citations
TL;DR: The modification and refinement of surface and subsurface microstructure in Al-Si-based cast alloys via laser-induced rapid solidification can create a natural topography suitable for engine applications as discussed by the authors.
Abstract: The modification and refinement of surface and subsurface microstructure in Al-Si-based cast alloys via laser-induced rapid solidification can create a natural topography suitable for engine applications. The differential wear of the soft aluminum phase, hard silicon, and CuAl in the cell, along with the divorced eutectic nanostructure in the intercellular region, is expected to produce and replenish microfluidic channels and pits for efficient oil retention, spreading, and lubrication.
12 citations
TL;DR: In this article, a laser-based technique was used to deposit Fe 3 O 4 on A319Al, producing an Fe 3 o 4 /Al reaction composite coating, which was evaluated by nanoindentation techniques employing both Berkovich and cube-corner indenters.
Abstract: A laser-based technique was used to deposit Fe 3 O 4 on A319Al, producing an Fe 3 O 4 /Al reaction composite coating. Scanning Auger microscopy indicated a reaction between oxide particles and aluminum-forming Fe–Al intermetallic compounds, Al 2 O 3 , and various intermediate reaction products. Analysis of the coating region, fractured in vacuo , indicated substantial toughness of the material due to extremely refined microstructure with finely distributed oxide and intermetallic particles and strong interfacial bonding between particles and the matrix. Mechanical properties of the coating were evaluated by nanoindentation techniques employing both Berkovich and cube-corner indenters. Hardness and elastic modulus values were found to be uniform at 1.24 and 76 GPa, respectively. No radial cracking was observed for either the Berkovich or cube-corner indenters. These results indicate that the laser-induced rapidly solidified composite material is tough and fracture resistant.
11 citations
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TL;DR: The current review casts new light on research related to the surface modification of biomaterials, especially materials for prosthetic applications, along with those that hold tremendous potential for bioimplant applications.
Abstract: Often hard implants undergo detachment from the host tissue due to inadequate biocompatibility and poor osteointegration. Changing surface chemistry and physical topography of the surface influences biocompatibility. At present, the understanding of biocompatibility of both virgin and modified surfaces of bioimplant materials is limited and a great deal of research is being dedicated to this aspect. In view of this, the current review casts new light on research related to the surface modification of biomaterials, especially materials for prosthetic applications. A brief overview of the major surface modification techniques has been presented, followed by an in-depth discussion on laser surface modifications that have been explored so far along with those that hold tremendous potential for bioimplant applications.
358 citations
TL;DR: In this paper, the authors reviewed the recent trends in materials technology and lubricant additive technology in engines and discussed the implications for boundary lubrication in the next decade and the extent to which materials and lubricants are being used in partnership in engineering systems.
289 citations
TL;DR: A critical review of the research into vehicle thermal management during the cold-start phase which has been driven by a desire to improve both engine and overall vehicle engine efficiency can be found in this paper.
283 citations
TL;DR: In this paper, the effects of surface modification by laser texturing on tribological performances of nitriding steel for high-performance engine applications were investigated, in particular, a comparison of tribological properties on untextured and textured 30NiCrMo12 (30NiCr6) steel was made among hydrodynamic, mixed and boundary lubrication regimes.
258 citations
TL;DR: In this paper, the recent progress and trends in the research and development of CMCs, TBCs, EBCs and SOFCs based on ceramic materials for high temperature applications are highlighted.
Abstract: The increasing interest in ecological aspects related to the reduction of harmful emissions to the atmosphere and, at the same time, the need to achieve higher efficiencies of energy production are the driving forces that justify the current development of advanced ceramic materials for high temperature applications, namely those associated to energy and transportation industries. Ceramic matrix composites (CMCs), thermal barrier coatings (TBCs), environmental barrier coatings (EBCs) and solid oxide fuel cells (SOFCs) are increasingly used to work under the new demanding conditions. In this review, the recent progress and trends in the research and development of CMCs, TBCs, EBCs and SOFCs based on ceramic materials for high temperature applications are highlighted.
177 citations