LOGO
Effect of nickel salts on the wear properties of
electrodeposited nanocrystalline Ni-Co coating
Chao Ma
Supervised by : Dr. Shuncai Wang
Prof. Frank Walsh
Outline
1. INTRODUCTION
2. METHODOLOGIES
3. RESULTS AND DISCUSSIONS
4. CONCLUSION
5. FUTURE WORK
LOGO
Introduction
LOGO
Nanocrystalline Wear and Corrosion Resistant Coatings
as an alternative to hard Cr deposits
Hard Cr
Electrodeposition
Cr(VI)
Eletrodeposition is a low-cost and versatile technique to form the nanocrystalline 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
Introduction
LOGO
High hardness
Nanocrystalline
Ni-Co coating
Good wear resistance
Good corrosion resistance
Introduction
LOGO
Process of
Electroplating
Hardness
Electrochemical
Corrosion
Behavior
Crystal Morphology
&
Microstructure
Tribology
Properties
METHODOLOGIES
2
1
Electroplating
LOGO
Microstructure
analysis
SEM&EDS, TEM, XRD
g/l
NiSO4•6H2O
NiCl2•6H2O
CoSO4 H2O
Additives
SS1
200
100
SS2
200
50
100
SS3
200
100
SS4
50
200
100
METHODOLOGIES
3
Tribology
test
LOGO
4
Friction and wear behaviour were tested on a
reciprocating pin-on-disc TE-77 tribometer
Hardness
test
Wear volume was measured by an optical 3D surface profilometer
RESULTS AND DISCUSSIONS
LOGO
Mixed structure of fcc and hcp
with (111)α preferred orientation
XRD
Independent of the nickel salts
TEM
NiCl2 electrolyte
25000
NiSO4 electrolyte
The finest grain size (5-10nm) is obtained from
the coating prepared by NiSO4 electrolyte.
RESULTS AND DISCUSSIONS
LOGO
SEM Morphologies
NiSO4 electrolyte
NiSO4-dominant electrolyte
Adding NiCl2
fine granular grains
lens shape
RESULTS AND DISCUSSIONS
LOGO
Tribology test
NiSO4 electrolyte
NiSO4-dominant electrolyte
0.8
SS1
0.7
SS2
Friction Coeff
0.6
0.5
0.4
0.3
0.2
0.1
0
50
Hardness
kg/mm2
Wear rate
10-4 mm3/Nm
503
2.34
150
250
Time / s
350
450
K= V/SF
352
5.32
V is the wear volume (in mm3)
S the total sliding distance (in m)
F is the normal load (in N)
The lens morphology significantly reduces the microhardness, which
leads to the increasing coefficient of friction and wear rate.
RESULTS AND DISCUSSIONS
LOGO
SEM Morphologies
NiCl2 electrolyte
NiCl2-dominant electrolyte
Adding NiSO4
pyramidal crystals
RESULTS AND DISCUSSIONS
LOGO
Tribology test
NiCl2-dominant
electrolyte
Friction Coeff
NiCl2 electrolyte
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
SS3
SS4
Hardness
kg/mm2
Wear rate
10-4 mm3/Nm
477
4.95
469
7.03
Traditional Archard’s Law
Q=KLN/H
150
Time / s
250
350
8
7
Friction of coefficient
Decrease of internal stress
Wear rate (10-4 mm3/Nm )
50
6
5
4
3
Debris
2
1
0
350
Wear rate
400
450
500
Microhardness (kg/mm2)
Variations of wear rate as a function of hardness
CONCLUSION
LOGO
Wear properties of electrodeposited nanocrystalline Ni-Co coatings
are affected by different kind of nickel salts in electrolyte
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.
The corresponding changes of the morphology and the crystal
may lead to different wear mechanisms
FUTURE WORK
LOGO
Relationship of processing-microstructure and crystal
morphology- tribological properties
Electrodeposited Ni-Co coating
Nucleation and growth of nanocrystalline
Morphology
Grain size
Phase structure
Internal stress
Hardness, Surface roughness, Adhesive interaction
Friction
Wear
UK-China Summer School
on Tribology & Surface Engineering
LOGO
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.uk
Tel. +44-(0)23-80594638
Thank you for listening
Questions?
LOGO