Copper micromachining using microorganisms

VYSAKH VASUDEVAN

10ME61R18

ME 1

INDIAN INSTITUTE OF TECHNOLOGY KHARAGPUR

Metal Eating Bacteria

Thiobacillus Ferroxidants are small bacillus having .5μm diameter and 1μm length

These bacteria can oxidize and reduce metals as part of their energy producing cycle

SEM micrograph of colony of A. Thiobacillus Ferroxidants

Biomachining:a new paradigm in manufacturingHigh

energy efficiency; low cost ; renewable tools; no HAZ…

.. micro channels for H.E

Techniques of Micromachining Using T. Ferrooxidants;AMM (’09)

Overall reaction releasing 8 kcal/mol energy:

Fe2+ + ½ O2 + 2H+ 2Fe3+ + H2O

Cu + 2Fe3+ Cu2+ + Fe2+

circulatory system of electron transfer.

Bio-machining Mechanism

Material processingMaterial processing

PhysicalRemoval

Cutting, griding,EDMAddition

Welding, spraying,PVDDeformation

Casting, forging,pressformingChemicalRemoval

Photo etching, chemical millingAddition

plating, CVDDeformation

Explosion formingBiologicalRemoval

BiomachiningAddition

BiodepositionDeformationBioforming

Organisms: classified

organisms

lithotroph

organotroph

chemolithotroph

photolithotroph

chemoorganotroph

photoorganotroph

carbon energy

CO2

CO2

Org.matter

Org.matter

Inorg.matter

light

light

Org.matter

Oxidation by A.Ferrooxidants

TECHNIQUES OFMICROMACHINING USING T. FERROOXIDANTS ; AMM vol 16-19 oct. 2009 ; www.scientific.net

Biomachining experimentBacterial culturing– tool preparationWorkpiece preparationProcedure for comparison of roughness & calculating the MRR

Bacterial culturing•Bacillus : A.F.ATCC 21834•Culture medium: 9 K26ºC ; 15ml tubes(NH4)2SO4 :3.0K2HPO4 :0.05KCl :0.10MgSO4.7H2O :0.50Ca(NO3)2.2H2O :0.01Fe2+ :5•pH : 2.0

FUNDAMENTAL STUDY OF BIOMACHINING; JSME INTL . JOURNAL C 1996

Workpiece preparation

FUNDAMENTAL STUDY OF BIOMACHINING; JSME INTL . JOURNAL C 1996

•High purity Cu blocks 12x12x12 mm3

•Cu foils 10x10 mm2

•Surface polishing•Preferential masking•Sanitizing•Profilometer•1 jar 9 K medium as control

Experiment setup

(a) •Bacterial culture

(b) •workpiece

(c) •Copper foil

(d) •Bio m/c process

Results

Before machining After machining

SEM micrographs of 800 grit polished surface

Before machining After machining

SEM micrographs of 220 grit polished surface

Effect of machining time on Ra value

800 grit polished Cu 220 grit polished Cu

Effect of machining time on MRR

Change in

mass of Cu foil

quantify the

MRR

Observations and inferences

Machining time did not linearly affect the change of Ra.Longer machining time - more randomised profile.Increasing Ra - a limitation of the biomachining process.Insignificant change of mass for the Cu foil kept for

control (0.0003g). 9K medium - negligible effect on MRRDecrease in MRR not merely due to depletion of oxygen.Decreasing nutrients ( ferrous sulfate) and increasing Cu2+

and hydrolysis reduce bacterial activity, reducing MRR.

ConclusionsA new metal removal process called biomachining using a

lithotrophic bacteria Acidithiobacillus Ferrooxidants was employed for Copper micromachining and the characteristics were evaluated experimentally

The arithmetic average of surface roughness (Ra) was found to increase with the machining time.

MRR was found to be inversely proportional to the machining time but not simply linear.

Reduction in MRR was caused by decrease in nutrients and increase in Cu2+ and hydrolysis and not merely due to reduction in oxygen.

References • A Study on copper micromachining using microorganisms

Jos Istiyanto, Tae Jo Ko, II Chae Yoon;

International Journal of Precision Engineering and Manufacturing; Vol 11; Oct 2010.

• Fundamental Study on Biomachining

Y Uno; T Kaneeda; s Yokomizo;

JSME International Journal; series C; Vol39; 1996.• Techniques of Micromachining Using Thiobacillus

Ferrooxidants Based on Different Culture Medium

Y Yang; X Wang; Y Liu; S Wang; W Wen;

Applied Mechanics and Materials; Vols 16-19; 2009.

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