The present work involves synthesis, characterisation and evaluation of hardness and sliding wear resistance of electrodeposited nanocrystalline Ni-Fe-W alloys. The crystallite size reduced with an increase in current density owing to an increase in the amount of alloying elements (Fe and W). Ni-Fe-W alloy with 23 at.-%Fe and 1.3at.-%W plated at 0.1 A cm-2 exhibited the maximum hardness of 563 HV. The alloys exhibited a direct Hall-Petch relation above a crystallite size of 12 nm and an inverse Hall-Petch relation below 12 nm. The wear resistance of the alloys increased with a reduction in the crystallite size in the direct Hall-Petch region and decreased in the inverse Hall-Petch region. Ni-Fe-W coatings with 23 at.-%Fe and 1.3at. -%W plated at 0.1 A cm-2 exhibited superior wear resistance. © 2006 Institute of Materials, Minerals and Mining.

S. Ganesh Sundara Raman

Department of Metallurgical and Materials Engineering

Suresh Krishnamoorthy Seshadri

current density

Electrodeposition

Electroplating

Hardness

Nanostructured materials

Wear resistance

INVERSE HALL-PETCH

NANOCRYSTALLINE COATINGS

NICKEL-IRON-TUNGSTEN ALLOYS

Sliding wear

Nickel alloys

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

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IIT Madras

Synthesis and evaluation of hardness and sliding wear resistance of electrodeposited nanocrystalline Ni–Fe–W alloys

Materials Science and Technology

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

The present work aims to study the hardness and wear resistance of electroless Ni-B coatings. An alkaline bath having nickel chloride as the source of nickel and borohydride as the reducing agent was used to prepare the electroless Ni-B coatings. The structure, microhardness and wear resistance of electroless Ni-B coatings, both in as-plated and heat-treated conditions, were evaluated using X-ray diffraction (XRD), Leitz microhardness tester and a pin-on-disc wear test apparatus. XRD patterns reveal that electroless Ni-B coatings are amorphous in as-plated condition and undergo phase transformation to crystalline nickel and nickel borides upon heat-treatment. The microhardness of the electroless Ni-B coatings increases with increase in heat-treatment temperature and exhibit two maxima in the hardness vs. heat-treatment temperature curve. The specific wear rate increases with increase in applied load from 20 to 40 N and at all applied loads, the specific wear rate and coefficient of friction are less for heat-treated electroless Ni-B deposits compared to that obtained for as-plated ones. The wear process of electroless Ni-B coatings is governed by an adhesive wear mechanism. © 2004 Elsevier B.V. All rights reserved.

Surface and Coatings Technology

Electroless Ni-B coatings: Preparation and evaluation of hardness and wear resistance

The present work deals with the formation of Ni-P/Ni-B duplex coatings by electroless plating process and evaluation of their hardness, wear resistance and corrosion resistance. The Ni-P/Ni-B duplex coatings were prepared using dual baths (acidic hypophosphite- and alkaline borohydride-reduced electroless nickel baths) with both Ni-P and Ni-B as inner layers and with varying single layer thickness. Scanning electron microscopy (SEM) was used to assess the duplex interface. The microhardness, wear resistance and corrosion resistance of electroless nickel duplex coatings were compared with electroless Ni-P and Ni-B coatings of similar thickness. The study reveals that the Ni-P and Ni-B coatings are amorphous in their as-plated condition and upon heat-treatment at 450 °C for 1h, both Ni-P and Ni-B coatings crystallize and produce nickel, nickel phosphide and nickel borides in the respective coatings. All the three phases are formed when Ni-P/Ni-B and Ni-B/Ni-P duplex coatings are heat-treated at 450 °C for 1h. The duplex coatings are uniform and the compatibility between the layers is good. The microhardness, wear resistance and corrosion resistance of the duplex coating is higher than Ni-P and Ni-B coatings of similar thickness. Among the two types of duplex coatings studied, hardness and wear resistance is higher for coatings having Ni-B coating as the outer layer whereas better corrosion resistance is offered by coatings having Ni-P coating as the outer layer. © 2003 Elsevier B.V. All rights reserved.

Materials Chemistry and Physics

Electroless Ni-P/Ni-B duplex coatings: Preparation and evaluation of microhardness, wear and corrosion resistance

Nickel composite coatings have been prepared on mild steel substrates by sediment electro-co-deposition (SECD) technique. Silicon nitride, fly ash and calcium fluoride are used as the reinforcements. Metallographic studies, microhardness, friction and wear tests under various loads and sliding speeds have been carried out on these coatings. Optical and scanning electron microscopy (SEM) studies on the worn surfaces were conducted. A theoretical model was used to predict the wear rates of the composite coatings. All the composite coatings exhibited a lower coefficient of friction and better wear resistance when compared with nickel coatings at all loads and sliding velocities studied. However, nickel-calcium fluoride composite coatings possessed the lowest coefficient of friction and wear rates. Significant effect of load and sliding speed on both the coefficient of friction and wear rates of nickel, nickel-silicon nitride and nickel-fly ash coatings has been observed. SEM studies of the worn surfaces reveal delamination process at higher loads. The predicted wear rates are in reasonable agreement with the experimental values. © 2003 Elsevier Science B.V. All rights reserved.

Wear

Tribological characteristics of nickel based composite coatings

Journal of Alloys and Compounds

The effect of the Cr and Mo on the physical properties of electrodeposited Ni–Fe alloy films

Acta Materialia

Mechanical behavior of nanocrystalline metals and alloys11The Golden Jubilee Issue—Selected topics in Materials Science and Engineering: Past, Present and Future, edited by S. Suresh

Synthesis and evaluation of hardness and sliding wear resistance of electrodeposited nanocrystalline Ni-Fe-W alloys

Journal	Materials Science and Technology
ISSN	02670836
Open Access	No