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Effect of nickel salts on the wear properties of electrodeposited nanocrystalline Ni-Co coating

Chao MaSupervised by : Dr. Shuncai Wang Prof. Frank Walsh

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1. INTRODUCTION

2. METHODOLOGIES

3. RESULTS AND DISCUSSIONS

4. CONCLUSION

5. FUTURE WORK

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Cr(VI)Hard Cr Electrodeposition

IntroductionNanocrystalline Wear and Corrosion Resistant Coatingsas an alternative to hard Cr deposits

Eletrodeposition is a low-cost and versatile technique to form the nano-crystalline coatings, which exhibit unique properties derived from their large number of grain boundaries compared to coarse-grained surface.

www.newworldencyclopedia.org/entry/Electroplating http://jolisfukyu.tokai-sc.jaea.go.jp/fukyu/tayu/ACT02E/06/0603.htm

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Good wear resistanceNanocrystallineNi-Co coating

Introduction

High hardness

Good corrosion resistance

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Electrochemical Corrosion Behavior Crystal Morphology

&Microstructure

Hardness

Process of Electroplating

Introduction

Tribology Properties

THE EFFECT OF NICKEL SALTS

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Microstructure analysis

2

Electroplating

1

METHODOLOGIES

SEM&EDS, TEM, XRDg/l SS1 SS2 SS3 SS4

NiSO4•6H2O

200 200 - 50

NiCl2•6H2O

- 50 200 200

CoSO4 H2O

100 100 100 100

Additives

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Hardnesstest

Tribology test

3

METHODOLOGIES

4

Wear volume was measured by an optical 3D surface profilometer

Friction and wear behaviour were tested on a reciprocating pin-on-disc TE-77 tribometer

LOGORESULTS AND DISCUSSIONS

0

50000

100000

150000

200000

250000

35 40 45 50 55 60 65 70 75

SS1 SS2

SS3 SS4

SS3

SS4

SS2

SS1

XRD

Mixed structure of fcc and hcpwith (111)α preferred orientation

Independent of the nickel salts

The finest grain size (5-10nm) is obtained from the coating prepared by NiSO4 electrolyte.

TEMNiCl2 electrolyte

NiSO4 electrolyte

LOGORESULTS AND DISCUSSIONS

SEM MorphologiesNiSO4 electrolyte

Adding NiCl2

fine granular grains lens shape

NiSO4-dominant electrolyte

LOGORESULTS AND DISCUSSIONS

50 100 150 200 250 300 350 400 4500

0.10.20.30.40.50.60.70.8

SS1 SS2

Time / s

Fric

tion

Coef

f

The lens morphology significantly reduces the microhardness, which leads to the increasing coefficient of friction and wear rate.

Tribology test

NiSO4-dominant electrolyte

Hardnesskg/mm2

503 352

Wear rate10-4 mm3/Nm

K= V/SFV is the wear volume (in mm3)S the total sliding distance (in m) F is the normal load (in N)2.34 5.32

NiSO4 electrolyte

LOGORESULTS AND DISCUSSIONS

SEM Morphologies

NiCl2 electrolyte

Adding NiSO4

pyramidal crystals

NiCl2-dominant electrolyte

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350 370 390 410 430 450 470 490 510012345678

Wear rate

Microhardness (kg/mm2)

Wea

r ra

te (1

0-4

mm

3/N

m )

Friction of coeffi-cient

Tribology test

Hardnesskg/mm2

477 469

Wear rate10-4 mm3/Nm

4.95 7.03

RESULTS AND DISCUSSIONS

Decrease of internal stress

50 100 150 200 250 300 3500

0.10.20.30.40.50.60.70.80.9

SS3SS4

Time / s

Fric

tion

Coef

f

Variations of wear rate as a function of hardness

Debris

Traditional Archard’s LawQ=KLN/H

NiCl2 electrolyte NiCl2-dominant electrolyte

LOGOCONCLUSION

Wear properties of electrodeposited nanocrystalline Ni-Co coatings are affected by different kind of nickel salts in electrolyte

The corresponding changes of the morphology and the crystal may lead to different wear mechanisms

The coating formed from NiSO4 electrolyte performs better tribological behaviour, which can be attributed to the finest grain size and the fine granular grain morphology. NiCl2 can increase the internal stress.

LOGOFUTURE WORK

Electrodeposited Ni-Co coating

Nucleation and growth of nanocrystalline

Morphology

Grain size Phase structure

Hardness, Surface roughness, Adhesive interaction

Internal stress

Friction Wear

Relationship of processing-microstructure and crystal morphology- tribological properties

LOGOUK-China Summer School on Tribology & Surface Engineering

23-25th August 2010 Chilworth Manor Hotel (2 mile away from the University of Southampton)

Sponsored by RCUK –Research Councils UK

General Chair (UK and China): Prof. R.J.K. Wood, Vice President of the International Tribology Council Prof. Weimin Liu, Vice President of the Chinese Tribology Institute 

CONTACT DETAILS OF ORGANIZING COMMITTEE: Dr. S.C. Wang E-mail: wangs@soton.ac.ukTel. +44-(0)23-80594638

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