Nano and microlayers against material deterioration in aggressive environment

Talah Abohalkuma

Supervisor: Dr. Telegdi Lászlóné

Material Science and Technology PhD School of Óbuda University

Nano and microlayers against material deterioration in aggressive

environment

Outline

Background Experimental Results Conclusion

Aim of study 1

2

5

4

3

 formation of self assembled molecular layers (SAM) on carbon steel and aluminum.

 influence of different variables (solvent, oxide layer, working

system (open or closed), temperature,pH, chloride ions, perchloride) on the protective layer formation.

 Contact angle measurement (presence of the layer)

 Atomic force microscopy (morphology of the layer)

 Electrochemical measurements: cyclic voltammetry

(compactness of the layer), potentiodynamic polarization techniques, and electrochemical impedance spectroscopy (anticorrosion activity).

Characterization of the formed layers

Study of

Effects of study

Solvent

Working System (open/ closed)

Perchloride ions

Chloride ions

Layer forming time

Immersion time in aggressive solution

Surface Precoating Method (Self assembly monolayers (SAM))

Effects of study

Open Circuit Potential

Potentiodynamic Polarization

Electrochemical Impedance Spectroscopy (EIS)

Cyclic Voltammetry

Leaner Plolarizatio

Wieght Loss Characterization

Dynamic Contact Angle Atomic Force Microscope

(AFM) Electrochemical Methods

 Electrochemical Impedance Spectroscopy (EIS)

 Atomic force microscopy (AFM)

 Perchloride ions

 Time of layer formation

 Time of immersion in aggressive solution

Fulfillment of the sixth semester

 Study the effect of:

 Characterization of the formed layers by:

 A presentation “Special phosphonic acid nanolayers for controlling corrosion processes” Chemical Engineering day, 21- 23 April 2015, Veszprém,- Hungary

 A journal publication “Corrosion protection of carbon steel by special phosphonic acid nanolayers” Materials and Corrosion. (IF 2.3)

 A journal publication (in review) “ Corrosion processes

controled by phosphonic acid nano- layers ” Periodica

Polytechnica Chemical Engineering. (IF 0.3)

Test Methods

Corrosion process

Methods of corrosion control

Electrolyt

Corrosion

Corrosion

Self-assembled monolayers (SAM)

Representation of a SAM structure

Component Composition

vs (SHE) Volts

vs SCE Volts

vs Ag/AgCl^- Volts

vs Cu/CuSO₄ Volts

(Pt) H₂/H⁺ l -0.241 -0.25 -0.30

Hg/Hg₂Cl₂/

sat KCl +0.241 l -0.009 -0.059

Ag/AgCl/

0.6 MCl^- +0.25 +0.009 l -0.05

Cu/CuSO₄ sat +0.30 +0.059 +0.05 l

Reference Electrode

(SHE) Standard Hydrogen

(SCE) Saturated Calomel Electrode Silver/Silver

Chloride (seawater) Copper/

Copper Sulphate

Conversion factors (to convert add the value indicated)

From E¹ To SHE Scale To SCE Scale

H₂/H⁺ (SHE) -0.241

Ag/AgCl sea water +0.25 +0.047

Hg/Hg₂Cl₂/sat KCl (SCE) +0.241

Cu/CuSO₄ +0.30 +0.06

Reference Electrodes

Potentiodynamic curve

(SI1287 Sorltron/Electrochemical Interface(Potentiostat ))

Electrochemical impedance spectroscopy (EIS)

(SI 1260 Impedance/ Gain- Phase

analyzer)

Atomic force microscopy (AFM)

Test Results

Udecenyl phosphonic acid

undecenyl phosphonic acid layer formed at 30min

and treated with NaClO4 for 2hrs.

undecenyl phosphonic acid layer formed at 30min

undecenyl phosphonic acid layer formed at

30min and treated with NaCl for 2hr.

fluorophosphonic layer formed at 30min and treated with NaCl

for 1hr.

fluorophosphonic layer formed at 30min.

EIS measurements for fluorophosphonic acid layer at different formation time and tested in NaClO4 solution

Effect of layer formation time

EIS for F.P layer formed at 3hrs -14000

-12000

-10000

-8000

-6000

-4000

-2000

0

0 5000 10000 15000 20000 25000 30000 35000

Re Z(ohm. cm²) Im Z (ohm. cm2 )

Bare metal F.P 30 min F.P 1hr

EIS measurements for undecenyl phosphonic acid layer at different formation time and tested in NaClO4 solution

EIS for U.P layer formed at 24hrs

-9000

-8000

-7000

-6000

-5000

-4000

-3000

-2000

-1000

0

0 5000 10000 15000 20000 25000 30000

Re Z (ohm. cm²) Im Z (ohm. cm2 )

Bare metal U,P 1 hr U.P 2hrs U.P 24hrs

EIS measurements for fluorophosphonic acid layer (2hr) on carbon steel in NaClO

solution

0 250 500 750

-750

-500

-250

0

Z'

Z''

Blank at 20min.z Blank at 2hr.z Balnk at 3hr.z

EIS measurements for undecenyl phosphonic acid layer (24hr) on carbon steel in NaClO

solution

0 5000 10000 15000 20000

-20000

-15000

-10000

-5000

0

Z'

Z''

Blank at 20min.z Blank at 2hr.z Balnk at 3hr.z 20min.z 4hr.z

-1.5 -1 -0.5 0 0.5 1 1.5

0.01 0.1 1 10 100 1000 10000

Current density [µA/cm²]

Potential [V]

Bare metal F.P 0.5h U.P 0.5hr

Potentiodynamic polarization curves for layers formed at 30min with different chemicals

(undecenyl and flourophosphonic acid) (NaClO4).

-1.5 -1 -0.5 0 0.5 1 1.5 2

0.0001 0.001 0.01 0.1 1 10 100 1000 10000

Current density [µA/cm2]

Potential [V]

Bare metal F.P 4hrs U.P 4hrs

Potentiodynamic polarization curves for layers formed at 4hrs with different chemicals (undecenyl and flourophosphonic acid)

(NaClO4).

-1.5 -1 -0.5 0 0.5 1 1.5

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000 10000

Current density [µA/cm²]

Potential [V]

F.P 48hrs U.P 48hr

Potentiodynamic polarization curves for layers formed at 48hrs with different chemicals (undecenyl acid phosphonic and flourophosphonic

acid) (NaClO4).

3 2

4 1

5

The EIS results show The undecenyl phosphonic acid and

fluorophosphonic acid layers performded protection of the metal surface agains aggressive solution.

Potentiodynamic results showed that the undecenyl phosphonic acid and fluorophosphonic acid had the same performance for layers formed at

30min and 48 hrs although tre was a differnece with layers formed at 4hrs.

Undecenyl phosphonic acid resulted in excellent protective layers against corrosion although it decreased after 4hr.

In case of fluorophosphonic acid, increasing the layer formation time led to decreasing the corrosion rate.

AFM showed that the effect of sodium chloride was more savior than that of

sodium perchloride where pitting corrosion occurred.