Notes on anodization process of Ti6Al4V. Its effect on mechanical properties and corrosion resistance.

1. Notes on Anodization of
Ti6Al4V
Khuram Shahzad

2. Anodizatoin Process
• Anondization or Anodic oxidation takes place by electrode reactions in combination with electric field driven metal and oxygen ion
diffusion leading to the formation of an oxide film on the anode surface. Anodic oxidation is a well-established method to produce
different types of protective oxide films on metals. Different diluted acids (H2SO4, H3PO4, acetic acid and others) can be used as
electrolytes in the process. The main technological advantage of anodizing titanium is improved adhesion and bonding, which is
particularly relevant in the aerospace industry. It can also be used to increase the oxide thickness to increase corrosion protection and
decrease ion release, coloration, and porous coatings. The structural and chemical properties of the anodic oxides can be varied over
quite a wide range by altering the process parameters, such as anode potential, electrolyte composition, temperature, and current.
X. Liu, et al., Surface modification of titanium, titanium alloys and related materials for biomedical applications, Materials Science and Engineering R 47 (2004) 49-121

3. Types of anodization
• Potentiostatically: at constant potential
• Galvanstatically: supplying a constant current
• Potentio dynamically: liner increase in potential with time
AW Hassel, Surface treatment of NiTi alloys for medical applications, Min Invas and Ther and Allied Technology 13 (4) (2004), 240-247

4. Applications Ti anodization
• To provide decroative finishing: Coloring
• To provide protection against atmospheric corrosion: stable
protective oxide layer formation
• To reduce friction on sliding surface: Hard (can be porous) layers
provide lubrication
• To provide thermal control
• Functionalization of medical implants for better bonding with tissue
and enhance cell growth on the implant
AK Sharma, Anodizing of Ti for space applications, Thin Solid Films 208 (1992), 48-54

5. Effect of voltage on color
Voltage: 10-120V
Anodizing time: 30s
Electrolyte: 0.4 M phosphoric acid
Sample thickness: 1 mm
Sample size: 20 x 30 mm2
Material- Ti6Al4V sheet
A. Karambaksh et. al., Corrosion resistance and color properties of anodized Ti6Al4V, JMEPEG, 21 (2012), 121-127.

6. Effect of applied voltage, during anodization,
on morphology of anodized layer
Ti anodization; a comparison with aluminium anodization, https://sundoc.bibliothek.uni-halle.de/diss-online/04/04H055/t6.pdf.

7. Effect of voltage on thickness and refractive
index of anodized layer

8. Effect of Anodizatio on Corrosio properties
A. Karambaksh et. al., Corrosion resistance and color properties of anodized Ti6Al4V, JMEPEG, 21 (2012), 121-127.

9. Effect of Anodizatio on Corrosio properties
A. Karambaksh et. al., Corrosion resistance and color properties of anodized Ti6Al4V, JMEPEG, 21 (2012), 121-127.
In general, the anodized samples zere suitable and stable in atmospheric environment for
structural applications.

10. Effect of anodiwation on Fatigue properties of
Al alloys
Decrease in fatigue strength of anodized coating specimens is due to formation of cracks at
an early stage of fatigue process induced by flaws in films.
K. Shiozawa et. al., Effect of anodized coating on fatigue strength in aluminium alloys, JMEPEG, 21 (2012), 121-127.

11. Effect of anodizing on Yield and Tensile
strength of
Yield and tensile strength of Al-Cu alloy 2024 is slightly higher for anodized samples. This can
be related to presence of hard coating around the samples.
X. Zhao, et. al., An analysis of mechanical properties of anodized aluminium film at high stress, JMEPEG, 21 (2012), 121-127.

12. Effect of anodizing on high cycle (320 MPa)
fatigue of aluminium alloys
X. Zhao, et. al., An analysis of mechanical properties of anodized aluminium film at high stress, JMEPEG, 21 (2012), 121-127.

13. Effect of anodizing on impact strength of
samples built by additive ,anufacturing
Charpy impact test shows that coating has no big influence on toughness, the variations in impact strength are associated to AM
process.
This is very important conclusion, AM process can also have a greater influence on other mechanical properties like fatigue test
and tensile test and generally these variations are so large that it can easily shadow the influence of anodization effect
Alexander Rex, Coating of additive manufacturing dental suprastructures and its interaction with veneering resin, 2016, Lund University Sweeden and Dentsply Sirona
Implants Hasselt.