"Sputtered Aluminum and titanium based coatings for improved oxidation resistance of magnesium", the oxidation's examination properties of magnesium (Mg) and potential coatings to upgrade or prevent of high temperature oxidation are analyzed. Aluminum, titanium and aluminum-titanium coatings are utilized as targets materials. All coatings are finished using magnetron sputtering.

1. Al/Ti Based Anti Corrosion
Coatings for Magnesium
Ben Stevens & Chiragraj Umesh Poojari
Supervisor's : A/Prof. RichardYang & Dr Leigh Sheppard

2. Why Protect magnesium?
▪ Magnesium is highly active metal*.
▪ Magnesium is the most chemically active of the metals used in
aircraft construction and is the most difficult to protect.
▪ Magnesium attack is probably the easiest type of corrosion to
detect in its early stages, since magnesium corrosion products
occupy several times the volume of the original magnesium
metal destroyed.
▪ Mg is important due to the low thermodynamic stability of
the corrosion products
* Magnesium tends to serve galvanic attack

3. Application Of Mg (Magnesium)
▪ Magnesium Compounds - A source of magnesium for the production
of magnesium salts*
▪ Magnesium alloys have the largest strength-to-weight ratio of
the common structural metals
▪ High specific strength
▪ Excellent clamping capacity
▪ Good thermal conductivity
Magnesium salts*- such as sulfates (Epsom salts), nitrates, acetates, chlorides, etc.

4. Aim
The Aim of the this project is to improve the high temperature
oxidation resistance of magnesium (Mg).
The project seeks to achieve this aim by investigating the
oxidation behavior of Al,Ti & AlTi coating.
1
2
3
Ti
Mg
Al
Magnesium ( substrate )
Layer 2
Layer 1
25 –
100 nm
Al2O3
MgO

5. Target material Selection
Titanium-Titanium and its alloys are light in weight,
and possess an extraordinary corrosion resistance
and excellent biocompatibility
Bridge Al/Ti - A possible solution to increase the
bonding strength between the titanium layer and the
magnesium substrate is to introduce an aluminum film
as a “bridge” to form a hybrid or sandwich structure.
Al layer was not strongly bonded with the Mg substrate
O2

6. Methodology and Experimental Procedure
Characterize the thermal oxidation behavior of Mg
Establish deposition protocols Magnetron sputtering for
depositionTi, Al andTi/Al multilayer coatings on Mg
Substrates
Characterize the thermal oxidation behavior ofTi/Al coated
Thermal
oxidation
uncoated
Mg
Ti, Al and
Ti/Al on Mg
Substrate
Thermal
oxidation
Ti/Al on Mg
1
2
3

7. Cut in to 10
mm x 10 mm
sections
17 minutes for
50 samples
Polished in 3
stages up to
0.04 μm
particle size
Ultrasonic bath
in ethanol
between stages
Approximately
30 minute
polishing time
for each side
Thermal
oxidation
uncoated
Mg
Ti, Al and
Ti/Al on Mg
Substrate
Thermal
oxidation
Ti/Al on Mg
Stage1
Mg substrate preparation
Cutting
Polishing
Establish thermal oxidation
properties of Mg
Annealing
Characterisation
Sample preparation
Characterize the thermal oxidation behavior of Mg1

8. ▪ Annealing of uncoated Mg
Thermal
oxidation
uncoated
Mg
Ti, Al and
Ti/Al on Mg
Substrate
Thermal
oxidation
Ti/Al on Mg
Temperature C
Time 400 C 450 C 475C 500C
2 hrs.
4 hrs.
6 hrs.
Magnesium ( subtract )
Layer 1
MgO
Characterize the thermal oxidation behavior of Mg1

9. Thermal
oxidation
uncoated
Mg
Ti, Al and
Ti/Al on Mg
Substrate
Thermal
oxidation
Ti/Al on Mg
Stage 2
Determine
deposition rates
Deposition of Al
andTi on Mg
Magnesium ( subtrate )
Coating
Al2O3
TiO2
Oxide
Establish deposition protocols for Magnetron sputtering for
depositionTi, Al andTi/Al multilayer coatings on Mg Substrates2

10. Thermal
oxidation
uncoated
Mg
Ti, Al and
Ti/Al on Mg
Substrate
Thermal
oxidation
Ti/Al on Mg
2
Titanium:
Average thickness = 520 nm
Time = 120 min
Deposition rate = 520 nm / 120 min = 4.33
nm/min
Above picture: Cross
section of Ti coating on Si.
Aluminium:
Average thickness = 794.76 nm
Time = 120 min
Deposition rate = 794.76 nm / 120 min =
6.623 nm/min
Establish deposition protocols for Magnetron sputtering for
depositionTi, Al andTi/Al multilayer coatings on Mg Substrates2

11. Thermal
oxidation
uncoated
Mg
Ti, Al and
Ti/Al on Mg
Substrate
Thermal
oxidation
Ti/Al on Mg
2
Run Target Dep Time
(s)
Thickness
(nm)
1 Ti 1386 100
2 Ti 693 50
3 Ti 347 25
4 Al 1813 100
5 Al 453 50
6 Al 227 25
7 Ti
Al
347
227
25
25
8 Ti
Al
693
453
50
50
9 Ti
Al
1386
1813
100
100
10 Al
Ti
227
347
25
25
11 Al
Ti
453
693
50
50
12 Al
Ti
1813
1386
100
100
• 12 variations of thin film coatings
• Ranging from 25 nm – 100 nm individual coatings
• Single and multi layer coatings
Magnesium ( subtrate )
Al [Thickness – 50(nm)]
DepTime Dep rate
Ti [Thickness – 50(nm)]
DepTime Dep rate
Establish deposition protocols for Magnetron sputtering for
depositionTi, Al andTi/Al multilayer coatings on Mg Substrates2

12. Thermal
oxidation
uncoated
Mg
Ti, Al and
Ti/Al on Mg
Substrate
Thermal
oxidation
Ti/Al on Mg
Stage 3
Annealing
Characterisation
SEM
SIMS
Magnesium ( substrate )
Coating
Wet O2
TiO2/
Al2O3
High
temperature
Characterize the thermal oxidation behavior of
Ti/Al coated on magnesium
3

13. Annealing of coated Mg
▪ Coated samples were annealed for 4 hours at 475°C in
wet oxygen rich environment
▪ Compared to uncoated samples
Characterisation of Coated Samples
▪ Surface morphology and film thickness examined using
SEM
▪ Oxide layer and passivity to be analysed using SIMS.
▪ SIMS analysis to be carried out at Hawkesbury campus
Today!
Characterize the thermal oxidation behavior of
Ti/Al coated on magnesium
3

14. Results and Discussion
Thermal
oxidation
uncoated
Mg
Ti, Al and
Ti/Al on Mg
Substrate
Thermal
oxidation
Ti/Al on Mg
3

15. Conclusion
• Ti much more resistant to high temperature oxidation than Mg
as expected
• Resistance to high temperature oxidation of Al is between Mg
andTi as expected
• Further analysis to determine properties of oxide layer to be
carried out
• Surface grain size vs deposition time to be further examined
• Passivity, interfacial diffusion through depth profiling to be
conducted

16. Acknowledgment
Special thanks
to
AProf. RichardYang ,Dr. Leigh Sheppard and
Dr. Richard Wuhrer for their help throughout.