A very short presentation on ELECTROCHEMICAL SURFACE STRUCTURING

1. Electrochemical Surface Structuring
Presented by
Srinjoy Guha
M. Prod. E. 2nd year
Roll No: 001411702010
Guided by
Dr. Bijoy Bhattacharyya
Professor, Production Engineering Department
Jadavpur University

2. Foreward
This is a seminar presentation on “Electrochemical Surface Structuring.” It is a
culmination of tasks undertaken by me during the six months’ tenure of 2nd semester of M.
Prod. E. course in Jadavpur University. It has been my greatest endeavor to be vivid, lucid
and illustrative as much as possible. The document consists of various theoretical
explanations along with suitable screenshots to ensure all readers an easy and clear
understanding. This has been an honest and sincere attempt from my side to reach a great
perfection level within a stipulated and limited time frame. So I ask prior forgiveness from
all careful, sensitive and beloved readers for all the unintentional errors those have been
committed from my side. However suggestions and criticisms for further improvement of
this seminar presentation is highly solicited.
Srinjoy Guha
7/1/2015Production Engineering Department, Jadavpur University.

3. What is Surface Structuring?
Surface Structuring is the process of manipulating the material surface with the objective
of enhancing its tribological properties. This means that with the help of surface structuring
the properties of surface can be enhanced. As for example with this we can enhance the
lubrication properties of the surface so that application of lubricating fluids get its best
functionality.
Along with this we all know that friction is most vital problem on all material surface
which makes it life less than actually it should be. This friction can be reduced by proper
application of surface structuring process.
That means with proper techniques of surface structuring we can enhance the lubricating
properties of the surface, reduce friction, reduce wear. Hence a less wastage of material is
noted!
7/1/2015Production Engineering Department, Jadavpur University.

4. Pros and Cons of Surface Structuring
Pros
1. Helps in developing surface properties of
material.
2. Frictional wear can be reduced to great
extent.
3. Lubricants used get their best
functionality.
4. Excellent surface finish of products for
precision manufacturing processes.
Cons
1. Initial cost of equipment is high.
2. It needs high level of expertise and hence
only professional people are authenticated
to perform it.
3. If the process isn’t well maintained,
negative results may occur i.e. the surface
properties can go down further.
7/1/2015Production Engineering Department, Jadavpur University.

5. Techniques of Surface Structuring
Conventional Techniques
Examples: Grinding, Honing, Lapping
Advantages:
1. Suitable to almost all types of materials
2. Easy equipment setup & low capital cost.
3. Economical process and low skilled labors can
perform.
Disadvantages:
1. Low accuracy, noisy operation and poor finishing.
2. Low tool life and higher material wastage.
3. Cant be performed on small dimension components.
Non-Conventional Techniques
Examples: Electric Discharge Machining,
Electrochemical Machining
Advantages:
1. Higher accuracy and surface finish and operation with
low or no sound.
2. More tool life and lower wastage of material.
3. Fully automated; no chance of human error.
4. Suitable for small dimension components.
Disadvantages:
1. High capital cost.
2. Not suitable for all materials e.g. EDM & ECM
requires electrically conductive materials.
3. Complex setup of equipment and experts required to
perform.
7/1/2015Production Engineering Department, Jadavpur University.

6. An overview of ECM and EMM
ECM and EMM are the mostly used process for surface structuring purposes. Electrochemical
machining (ECM) is a method of removing metal by an electrochemical process. It is normally used
for mass production and is used for working extremely hard materials or materials that are difficult to
machine using conventional methods.
When electrochemical machining process (ECM) is applied to micro machining range i.e. 1 micron
to 999 micron, for manufacturing of ultra-precision shapes then this is termed as electrochemical
micro machining or EMM process.
Rate of dissolution or material removal rate depends upon atomic weight of the material (a),
valance (v) of ions produced, machining current (I), and the time (t) for which the current passes.
Though the shape of electrodes remain unaltered like ECM. Material removed can be calculated as
MRR= Iaη/Fvρ
Where η= metal dissolution efficiency, ρ= density of material and F= Faraday’s constant= 96500
coulomb.
Applications of ECM and EMM related to surface structuring process:
1. Oxide Film Laser Lithography (OFLL)
2. Micro and Nanometer scaled surface structuring
3. Laser Electrochemical Micro Machining (LECMM) 7/1/2015

7. New Development of EMM for Titanium
Surface Structuring
1. Oxide film laser lithography: This process is similar to the ordinary lithography process
except the fact that here layer by layer development is made with typical laser spot diameter
used for Oxide Film Laser Lithography or OFLL.
2. EMM of multilevel structures: EMM using the photoresist technique is usually applied
to single step etching of flat surfaces, using one sided or two sided attack of thin sheet
samples. More recently the applications off EMM to the fabrication of two level structures
have been initiated.
3. Scale dependent surface structuring: Control of surface topography on the micro and
Nano scale is important in many applications (e.g. biomedical) and for that purpose this has
been a fast growing technique.
7/1/2015Production Engineering Department, Jadavpur University.

8. Scale dependent surface structuring
Control of surface topography on the micrometer and the nanometer scale is of
importance in many applications. Electrochemical etching can for example be used for
producing polished or grained surfaces of aluminum. The surface topography of biomedical
implants plays an important role for cell attachment and differentiation. For example, the
surfaces of dental implants made of titanium are subjected to physical and chemical
treatments that produce finely textured surfaces in order to reduce the time of recovery for
the patients.
Using an ethanol cooled sample holder and an optimized voltage function well defined
regular surface structures on 1.5 cm diameter polished disks were made as illustrated by the
SEM micrograph.
7/1/2015

9. The sample surface outside the cavities is the original mechanically polished surface,
whereas the inside of the cavities has an electro polished surface finish. Varying the cavity
size and distance one, therefore, also varies the ratio between electro polished and
mechanically polished surfaces. The effect of these variables on cell response is being
tested at present. Surface topography at the nanometer scale is thought to be at
least as important for cell response as micrometer scale topography. For titanium,
chemical etching in hot sulphuric and hydrochloric acid based electrolytes can
produce roughness on a sub micrometer scale. By superposing this type of nano-roughness with electrochemical
micro structuring one can produce surfaces with controlled roughness at two different scales. An example of such
a surface is given in the below figure.
For titanium a similar pore formation mechanism has very recently been reported in presence of fluoride at very
long anodisation times. Anodisation in sulphuric or phosphoric acid,
leads to the formation of a compact film, which at sufficiently high voltage
Undergoes dielectric breakdown leading to formation of a multitude of pores,
the size & number of which depends on experimental conditions. The breakdown
Events manifest themselves by marked current fluctuations. As an illustration,
the SEM picture of the below figure shows the surface of a porous anodic oxide
Film formed in 1 M H2SO4 by sweeping the voltage up to 125 V.
7/1/2015Production Engineering Department, Jadavpur University.

10. Interestingly, on mechanically polished samples the pores were quite regularly distributed, almost
independent of the grain structure of the underlying substrate. On the other hand, pore formation on
flat electro polished surfaces was in general less regular. By porous anodizing of electrochemically
structured titanium surfaces containing 30 mm size cavities, scale resolved surface structuring on the
micrometer and the nanometer scales could be achieved. An example of such a surface is shown in
the below figure.
The ability to fabricate well-defined surface topographies will be useful for reaching a better
understanding of the complicated interactions of living cells with implant materials.
7/1/2015Production Engineering Department, Jadavpur University.

11. Conclusion
In the present paper a brief overview has been given first of the basic principles governing the
performance of ECM and further the discussion has been concentrated to EMM. Recent studies on EMM
of titanium with and without photoresist discovered, which demonstrate the many possibilities of the
process for biomedical and micromechanics applications. In particular, EMM can be used for scale
resolved surface structuring on the micrometer and nanometer scales. Using oxide film laser lithography
instead of conventional photoresist technique, the usefulness of EMM can be extended to non-planar
surfaces and to the machining of multilevel structures for device fabrication. These developments together
with a better theoretical understanding of the critical electrochemical parameters are expected to eventually
open new fields of application for EMM. Future work should be aimed at finding ways to accelerate the
different steps involved in resist-free EMM in order to improve the economic attractiveness of the process.
Another possible development could be to use other means of oxide sensitization such as electron or ion
beams, which would permit to extend OFLL to machining of nano size features. The techniques described
here for titanium can probably be extended to other valve metals such as tantalum or niobium, although the
specifics of oxide sensitization may require further study and optimization of the interaction of laser
radiation with oxide films. 7/1/2015

12. References
1. “Advancement in Electrochemical Micro Machining” by Dr. B. Bhattacharyya, J.
Munda, M. Malapati.
2. “Electrochemical micromachining, polishing and surface structuring of metals:
fundamental aspects and new developments” by D. Landolt, F. Chauvy, O. Zinger.
3. “Electrochemical Micro Machining” by Todkar Mahesh.
7/1/2015Production Engineering Department, Jadavpur University.

13. THANK YOU
7/1/2015Production Engineering Department, Jadavpur University.