The present study deals with corrosion behaviour of compositionally modulated nanocrystalline Ni–W alloy coatings and conventional hard chrome coatings. Compositionally modulated Ni–W alloy coatings of known composition were systematically deposited using pulse current deposition. The corrosion behaviour was analysed using potentiodynamic polarization and impedance spectroscopy in 2N H2SO4. Compositionally modulated Ni–W alloy coatings depicted substantial improvement in corrosion resistance over its single-layer counterpart and hard chrome coatings. The corrosion behaviour was rationalized based on porosity and surface residual stresses present in these coatings. © 2019, © 2019 Institute of Materials, Minerals and Mining Published by Taylor &amp; Francis on behalf of the Institute.

Sundararajan G

Department of Metallurgical and Materials Engineering

Chromate coatings

corrosion

Corrosion resistance

Corrosion resistant alloys

Corrosive effects

Electrochemical corrosion

Electrodeposition

Hard coatings

Multilayers

Nanocrystalline alloys

Nanocrystals

Porosity

Residual stresses

ALLOY COATINGS

Corrosion behaviour

HARD CHROMES

Impedance spectroscopy

NANOCRYSTALLINE NI

NICKEL-TUNGSTEN

PULSE CURRENTS

SURFACE RESIDUAL STRESS

CORROSION RESISTANT COATINGS

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Corrosion behaviour of compositionally modulated nanocrystalline Ni–W coatings

Surface Engineering

Ni-W alloys with 16–28 at% tungsten (W) content were electrodeposited from citrate bath utilizing various pulse parameters. The influence of pulse parameters on microstructure, composition and mechanical properties was systematically studied. The corrosion behavior was analyzed in 1 M H2SO4 using potentiodynamic polarization and electrochemical impedance spectroscopy. Nanocrystalline Ni-W coatings were found to have superior corrosion resistance compared to their duplex nanocrystalline-amorphous counterpart. The corrosion behavior was rationalized based on semiconducting properties of oxide film using Mott–Schottky analysis and depth wise composition analysis utilizing X-ray Photoelectron Spectroscopy. An attempt is made to correlate corrosion current with intercrystalline defects. © 2019 Elsevier Ltd

Corrosion Science

Influence of pulse parameters on the mechanical properties and electrochemical corrosion behavior of electrodeposited Ni-W alloy coatings with high tungsten content

In the present work, the influence of molybdenum (Mo) content on the grain size, hardness, corrosion and wear behavior of Ni-Mo alloy coatings electrodeposited from citrate electrolyte has been studied. Crack free Ni-Mo alloy with different Mo content (3, 5, 6, 9 and 12 at.%) was obtained using direct current and pulsed current electrodeposition. It was observed that the grain size of Ni-Mo alloy decreased with increase in Mo content. Hardness of the coatings increased with Mo content and decreased subsequently above 9 at.% Mo as per inverse Hall-Petch effect. Potentiodynamic polarization tests carried out in 2 N H2SO4 suggested increase in both corrosion current and passive current density with increase in Mo content. In addition, both friction coefficient and dry sliding wear rate of Ni-Mo coatings decreased with increase in Mo content. The results are rationalized based on grain size and Mo content in the coatings. Finally, Ni-Mo and Ni-W coatings were compared with hard chrome with respect to mechanical properties, wear and corrosion resistance. Results indicated that, Ni-Mo coatings exhibit least friction coefficient (0.2–0.3) amongst Ni-W and hard chrome coatings. © 2019

Surface and Coatings Technology

Influence of molybdenum on the mechanical properties, electrochemical corrosion and wear behavior of electrodeposited Ni-Mo alloy

The present work deals with evaluation of corrosion behaviour of electrodeposited nanocrystalline Ni-W and Ni-Fe-W alloys. Corrosion behaviour of the coatings deposited on steel substrates was studied using polarization and electrochemical impedance spectroscopy techniques in 3.5% NaCl solution while their passivation behaviour was studied in 1N sulphuric acid solution. The corrosion resistance of Ni-W alloys increased with tungsten content up to 7.54 at.% and then decreased. In case of Ni-Fe-W alloys it increased with tungsten content up to 9.20 at.% and then decreased. The ternary alloy coatings exhibited poor corrosion resistance compared to binary alloy coatings due to preferential dissolution of iron from the matrix. Regardless of composition all the alloys exhibited passivation behaviour over a wide range of potentials due to the formation of tungsten rich film on the surface. © 2007 Elsevier B.V. All rights reserved.

Materials Science and Engineering A

Corrosion behaviour of electrodeposited nanocrystalline Ni-W and Ni-Fe-W alloys

Wear

Sliding wear behavior of electrodeposited Ni–W alloy and hard chrome coatings

Electrochimica Acta

Mechanical Properties of Electrodeposited Ni-W ThinFilms with Alternate W-Rich and W-Poor Multilayers

A simultaneous screening of the corrosion resistance of Ni–W thin film alloys

Journal	Data powered by TypesetSurface Engineering
Publisher	Data powered by TypesetTaylor and Francis Ltd.
ISSN	02670844
Open Access	No