Outline Curriculum (5 lectures) Each lecture ? 45 minutes

1
Outline Curriculum (5 lectures)Each lecture ? 45
minutes

• Lecture 1 An introduction in electrochemical
  coating
• Lecture 2 Electrodeposition of coating
• Lecture 3 Anodizing of valve metal
• Lecture 4 Electroless deposition of coating
• Lecture 5 Revision in electrochemical coating

2
Lecture 1 of 5An Introduction In
Electrochemical Coating
3
Electrochemical Surface Engineering(Electrochemic
al Coating)

• Is it about the deposition a coating onto
  surface, via electrochemical reactions.
• The coating can be (a) metallic, (b) metal oxide
  or (c) conductive polymer.
• Metallic coating Electroplating
• Metal oxide, conductive polymer Anodizing
• Electroless deposition

4
Electrochemical Surface Engineering

• An electro-chemical reaction
• Cathode Metals/alloys coating
• Anode Metal oxides
• Conductive solution ionic species
• Transfer of electrons

5
Electroplating of copper
6
Anodizing

• An electrolytic passivation process.
• To form a thick oxide layer on a metal.
• Metal oxide forms on the anode.

7
Electroless deposition

• Electroplating consisting of two electrodes,
  electrolyte, and external source of current.
• Electroless deposition this process uses only
  one electrode and no external source of electric
  current.
• Electroless deposition the solution needs to
  contain a reducing agent so that the reaction can
  proceed
• Metal ion Reduction solution
• ? Metal solid oxidation solution

Catalytic surface
8
Definition Electron transfer reactions

• Oxidizing agent n e- Reducing agent
• Oxidizing agents get reduced
• Reducing agents get oxidized
• Oxidation is a loss of electrons (OIL)
• Reduction is a gain of electrons (RIG)

OILRIG
9
Industrial scale anodizing of Aluminium
10
Example of anodizing
11
Brush electroplating of gold onto stainless steel
substrate
12
Tin-Zinc coating onto steel substrate

• Benefits of electroplated
• metallic surfaces
• Improved corrosion resistance.
• Improved wear resistance.
• Longer lifetime.
• Aesthetic surface finish.

13
Optical micrograph of 21 mm PEO coating on Mg
alloy
14
Optical micrograph of 12 mm PEO coating on Mg
alloy
15
Porosity in electroless Ni-P deposits (lt5 mm) on
mild steel
16
Log-log Porosity vs. thickness for electroless
Ni-P deposits on steel
17
Electrochemical anodizingTransformation of Ti
foil to TiO2 nanotubes
Anodizing e.g. 10-100 V
18
Green electrolyte, CH3SO3HAnodizing of TiO2
nanotubes from Ti foil
100 nm
100 nm
200 nm
200 nm
19
Surface microstructureNanotubes Au-TiO2
vertically aligned array
100 nm
1 ?m
100 nm
20
Reflective nanocrystalline PbO2 Application
Solar heat absorber
20
21
Rotating Cylinder ReactorHigh throughput
electrodeposition Cu-Sn alloys
22
Rotating Cylinder ReactorHigh throughput
electrodeposition Cu-Sn alloys
23
Nanoparticles SiC in a nickel matrixWear
resistance coating
Darker contrast nanoparticle SiC
100 nm
Ni-SiC coating
Copper substrate
200 ?m
24
TEM imageNanotubes TiO2 in a nickel matrix
Nanotubes TiO2
20 nm
Nickel matrix
100 nm
25
Electrodeposition of polypyrrole
Stainless steel substrate
Polypyrrole
1.0 cm
1.0 cm
25
26
Electrocatalysts for H2O electrolysis
Nanocrystalline and amorphous Ni-Co alloys
0g Co
2 g
10 g
20 g
40 g
60 g
80 g
100 g
150 g
200 g
100g Ni
1.0 cm
Co content in alloyed electrocatalyst increases
More effective electrocatalyst to evolution oxygen
26
27
Large scale electrodepositionThick film,
multilayered Ni-Co on Fe substrate
Each tank 5 Litres
20 cm
28
Multilayered ?- and ?-PbO2
a- and ß-PbO2
ß-PbO2
28
29
Thin film lead-acid batteryNanosized materials
Nanosized material PbO2 PbSO4
100 nm
29
30
Summary

• Electrochemical coatings range from nanoparticles
  of
• metal on nanostructured, inorganic supports
  through
• to hard lt100 mm Cr coatings on steel.
• Applications include catalysts, fuel cell-, solar
  cell- and battery electrodes together with
  tribological/corrosion resistant coatings for
  electronic materials, transport and heavy
  engineering.
• Plasma electrolytic oxidation uses the
  application of a high a.c. voltage to produce a
  hard, wear resistant oxide coating on light
  metals (such as Mg alloys) for automotive,
  aerospace and leisure.
• Electroless Ni deposits (typically lt20 mm in
  thickness) on steel or Al alloys are widely used
  in engineering applications for their corrosion
  and wear resistance. Thin coatings tend to have
  high porosity.