With the advent of the nano-era, a pronounced interest in the nanolayers has emerged. The develop-ment of more and more sophisticated measurement devices and techniques made possible the visualiza-tion, characterization and investigation of nanolayers. However, there exists a variety of simple, old means which should not be despised either. In this work, the use of contact angle measurement as a simple, fast, inexpensive and accessible tool for the study of surfaces with and without nanolayers is demonstrated. Furthermore, it is evidenced that in contrast to its simplicity, contact angle measurement can address sur-prisingly complex questions and give proper answers to these.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3525

Mohos, M.

Nyikos, L.

Romаnszki, L.

Telegdi, J.

SocioEconomic Challenges Journal (Sumy State University)

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  
NANOMATERIALS: APPLICATIONS AND PROPERTIES 
Vol. 2 No 1, 01PCSI04(3pp) (2013) 
 
 
2304-1862/2013/2(1)01PCSI04(3) 01PCSI04-1  2013 Sumy State University 
Contact Angle Measurement is an Efficient Tool for the Characterization of Corrosion Pro-
tection Nanolayers on Copper Alloys and Stainless Steel 
 
L. Románszki1,*, M. Mohos1,†, J. Telegdi1,2,‡, L. Nyikos1,§ 
 
1 Department of Interfaces and Surface Modification, Institute of Materials and Environmental Chemistry, Research 
Centre for Natural Sciences, Hungarian Academy of Sciences, Pusztaszeri út 59–67., 1025 Budapest, Hungary 
2 Institute of Media Technology and Light Industry, Faculty of Light Industry and Environmental Engineering, 
Óbuda University, Doberdó u. 6., 1034 Budapest, Hungary 
 
(Received 19 April 2013; published online 29 August 2013) 
  
With the advent of the nano-era, a pronounced interest in the nanolayers has emerged. The develop-
ment of more and more sophisticated measurement devices and techniques made possible the visualiza-
tion, characterization and investigation of nanolayers. However, there exists a variety of simple, old means 
which should not be despised either. In this work, the use of contact angle measurement as a simple, fast, 
inexpensive and accessible tool for the study of surfaces with and without nanolayers is demonstrated. 
Furthermore, it is evidenced that in contrast to its simplicity, contact angle measurement can address sur-
prisingly complex questions and give proper answers to these. 
 
Keywords: Nanolayer, Microbiologically Influenced Corrosion, Contact Angle, Aluminium Brass, Copper-
Nickel, Stainless Steel, Self-assembled Monolayers. 
 
  PACS numbers: 81.65.Kn, 81.65.Cf, 64.75.Yz, 81.65.Cf 
 
 
                                                          
* romanszki.lorand@ttk.mta.hu 
† mohos.miklos@ttk.mta.hu 
‡ telegdi.judit@ttk.mta.hu 
§ nyikos.lajos@ttk.mta.hu 
1. INTRODUCTION 
 
Aluminium brass (Al-brass), copper nickel 70/30 
(CuNi) [1] and stainless steel 304 (SS) [2] are im-
portant alloys in the energy sector. Due to their good 
heat conductivity and corrosion resistance, the former 
two are often used as materials of the cooling circuits of 
power plants operating with seawater as a cooling 
agent, while SS is a common material of fresh water 
tubings. 
In the presence of microorganisms, all these alloys 
suffer, to some extent, from biofouling and the conse-
quent microbiologically influenced corrosion. Means to 
protect these alloys include dosage of biocides to control 
the growth of microorganisms and inhibitors for the 
corrosion protection. However, none of these are always 
successful. In severe cases, the developed thick biofilm 
can only be removed by manual cleaning, and during 
the maintenance shutdown of complete power plant 
blocks may become unavoidable [3–5]. 
Ultrathin organic protection layers, such as self-
assembled monolayers (SAMs) and Langmuir–Blodgett 
films have been proven efficient in laboratory experi-
ments against both the corrosion itself and the adhe-
sion of microorganisms [6–9]. However, their reduced 
stability in aqueous environment set a limit to their 
industrial applicability [10]. In the coating industry, a 
proper pretreatment of the respective surface to be pro-
tected is the prerequisite of the success of the coating 
procedure and the performance of the protection layer. 
However, thorough cleaning is often time consuming 
and costly.  
Similarly, in laboratory experiments with SAMs, 
surface pretreatment may be an important, but circui-
tous process step. It is therefore desirable to investi-
gate the necessity of it. 
Contact angle (CA) measurement is a basic tool to 
characterize surfaces. In spite of that it offers much 
useful information to be extracted from, generally it is 
applied to serve rather modest purposes only, such as 
differentiation between a hydrophobic and a hydro-
philic surface. 
Through our experiments, we attempted to answer 
the question whether CA measurements could be used 
in a more efficient way in order to obtain information 
about the success of the nanocoating procedure and the 
stability of the prepared layer, especially in conjunction 
with the pretreatment of the substrate surface.  
 
2. EXPERIMENTAL 
 
Aluminium brass, copper-nickel and stainless steel 
alloy specimens were of 10×12 mm2 dimension, and cut 
from standardized tubes [1–3], therefore being curved, 
with approx. 12.7 mm (0.5 in) radius of curvature. 
Octadecanoyl hydroxamic acid (C18N) was synthe-
sized from hydroxylamine and the appropriate acyl 
chloride. Octadecyl phosphonic acid (C18P) was synthe-
sized in a Michaelis–Arbusov reaction. The products 
were re-crystallized and characterized by melting 
points, elemental analysis, infrared spectroscopy and 
thin layer chromatography. 
As substrate cleaning, 10 min. sonication in spectro-
scopic grade acetone was applied, occasionally complet-
ed by 20 min. cleaning in ozone generated under an UV 
lamp. 
SAM coatings were prepared by dipping the pre-
treated metal samples into 2.0 mM solutions of the film 
forming compounds (C18N, respectively C18P) in chlo-
 L. ROMÁNSZKI, M. MOHOS, J. TELEGDI, L. NYIKOS PROC. NAP 2, 01PCSI04 (2013) 
 
 
01PCSI04-2 
roform, dichloromethane, or tetrahydrofurane. Dipping 
times were 1, 5 and 24 h in the case of the alloys. The 
coated samples were rinsed with the respective solvent 
in order to remove non-specifically bond excess material 
and were dried in air or in a stream of nitrogen. 
The alloy samples, with and without coatings, were 
characterized by their advancing and receding CAs. 
Static sessile drop measurements were carried out us-
ing a home-built measurement device equipped with a 
Hamilton micropipette and a CCD camera. For the dy-
namic Wilhelmy-type CA measurements a digital sur-
face tensiometer (Nima) was used. Samples were auto-
matically dipped into and pulled out from water with a 
rate of 10 mm/s, while the apparent weight change of 
the target sample was registered. The CAs were re-
trieved by inputting the cross sectional dimensions of 
the samples and the surface tension of the water. Ul-
trapure water (MilliQ) was used as a measurement liq-
uid in both cases. 
A stability test of the SAMs in flowing water was 
conducted for 2 weeks. Dynamic CAs were measured 
before and after the test. In this latter case the samples 
were first thoroughly dried. 
 
3. RESULTS AND DISCUSSION 
 
Dynamic CA measurements of as-received and 
cleaned samples showed the effect of the cleaning pro-
cedure (Fig. 1). Al-brass samples exhibited higher ad-
vancing and receding CAs than CuNi samples, which 
exhibited higher values than SS samples, both in as-
received and in cleaned  state. In this same order, the 
effect of cleaning became more and more pronounced, 
from about 20° advancing CA difference in the case of 
Al-brass, 30° in the case of CuNi and 35° in the case of 
SS. Similarly, the receding CA differences were 5, 15 
and 16° for the three alloy types, respectively. 
 
 
 
Fig. 1 – Advancing and receding CAs of as-received vs. 
cleaned alloy samples, averaged for 4 parallel sample of each 
type, measured in 6 consecutive dipping cycles in a Wilhelmy-
type dynamic measurement 
 
The change in the CAs during the consecutive dip-
ping cycles was spectacular (Fig. 2). In the case of the 
as-received samples, advancing CAs initially increased, 
while receding CAs monotonously decreased in each 
new cycle. Contrarily, cleaned samples showed not only 
lower CAs, but also much more stable ones. 
When the effect of the cleaning on the C18N-SAM 
formation was studied, it was found that after the com-
plementary UV cleaning step the static CA of all alloy 
types decreased approx. to the same value (32-35°), as 
an indication of a more pronounced hydrophilicity. 
When SAM preparation was carried out after this UV 
step, the high CAs on Al-brass and SS (90°) indicated 
the formation of a SAM. However, in the case of 
Al-brass, SAM preparation proved to be successful also 
when performed after a simple acetone-cleaning 
(CA  92°), apparently not effective in the case of SS 
(CA  66°). 
Wilhelmy-type CA measurement can be used in or-
der to learn about the short-term stability of such nano-
coatings, as suggested by our results (Fig. 4). When sub-
tracting the values of advancing CAs of the same sam-
ples obtained in two consecutive immersion cycles, a few 
degrees differences can be noticed, as already shown in 
Fig. 2. The difference depends on the alloy type and has 
a large statistical spread, but it is generally negative, 
i.e. the surfaces become slightly more hydrophilic after 
each new immersion step, as an indication that the 
structure of SAM layers is slightly altered in water. 
 
 
 
Fig. 2 – Advancing and receding CAs of as-received vs. 
cleaned alloy samples in the consecutive dipping cycles of the 
Wilhelmy-type dynamic measurement 
 
When these differences are plotted as a function of 
the preparation time of the SAM, a reasonable trend 
becomes obvious: the longer the initial SAM preparation 
time was (the time allowed the molecules to adopt the 
best possible arrangement on the surface), the lower 
this difference is during the immersions. The larger 
differences are usually measured for the uncoated con-
trol samples, as obviously the wetting of these ones pro-
gresses with the fastest rate.  
 
   Ac             Ac+UV          Ac+SAM    Ac+UV+SAM 
Al-brass  
          63                  32      92           90 
SS   
           56                 35      66           90 
 
Fig. 3 – The effect of surface cleaning on the C18N-SAM for-
mation, as revealed by static CAs (°) of different alloy surfac-
es. Ac: cleaned in acetone; Ac+UV: cleaned in acetone, fol-
lowed by an UV-cleaning step; Ac+SAM: SAM formation after 
acetone- cleaning; Ac+UV+SAM: SAM formation after ace-
tone- and UV-cleaning 
 CONTACT ANGLE MEASUREMENT IS AN EFFICIENT TOOL… PROC. NAP 2, 01PCSI04 (2013) 
 
 
01PCSI04-3 
In accord with these above facts, CA measurement 
proved to be effective also in the correct estimation of 
the long-term stability of these nanolayers. Layers pre-
pared for 1, 5 and 24 h respectively were measured in 
three consecutive cycles both before and after a two 
week long stability test in flowing water. Taking the 
after/before advancing CA differences in any measure-
ment cycle, we found very drastic CA decrease after the 
test, indicating a pronounced hydrophilicity originating 
from a pronounced layer alteration in the water (Fig. 5). 
 
 
 
Fig. 4 – Short-term stability of C18N-SAM coatings: wetting 
during Wilhelmy CA measurement cycles (advancing CA dif-
ferences between the second and the first immersion cycles) in 
function of allowed self-assembly time 
 
However, this lowering of the CA showed very 
strong dependence on the SAM preparation time. The 
layers allowed to build up for 1 h only showed the larg-
est CA fall (about 45-50°), the ones prepared for 5 h 
showed only 40°, while the ones assembled for 24 h 
showed only 25-30°. We found it particularly spectacu-
lar that these simple CA measurements could lead to 
the same conclusion as our previous, more sophisticated 
reflection absorption infrared spectroscopy (RAIRS) and 
sum frequency generation spectroscopy (SFG) investiga-
tions [10]. This fact points out the hidden possibilities 
laying in the CA measurements. 
 
 
 
Fig. 5 – Long-term stability of C18P-SAM coated Al-brass 
samples for 2 weeks in flowing water. After-before advancing 
CA differences in the 1st (light grey), 2nd (grey) and 3rd im-
mersion cycles (dark grey) as function of self-assembly time 
 
4. CONCLUSIONS 
 
The main conclusion of this work is that, as demon-
strated above, simple, fast, inexpensive and accessible 
CA measurements can provide answers to surprisingly 
deep questions. 
 
ACKNOWLEDGEMENTS 
 
József Maráczi is acknowledged for the construction 
of the sessile drop CA goniometer. The research leading 
to these results has received funding from the Europe-
an Community's Seventh Framework Programme 
FP7/2007–2013 under grant agreement n°238579. 
 
 
REFERENCES 
 
1. Standard specification for copper and copper-alloy seam-
less condenser tubes and ferrule stock, Designation: B 111 
– 98 (Reapproved 2004) (ASTM International: 2004). 
2. Standard specification for welded austenitic steel boiler, 
superheater, heat-exchanger, and condenser tubes, Desig-
nation: A 249/A 249M – 04 (ASTM International: 2004). 
3. P. Cristiani, Appl. Therm. Eng. 25, 2630 (2005).   
4. P. Cristiani, G. Perboni, A. Debenedetti, Electrochim. Acta 
54, 100 (2008). 
5. Techniques for corrosion monitoring (Ed. L. Yang) (Cam-
bridge: Woodhead Publishing Ltd.: 2008). 
6. J. Telegdi, L. Románszki, F. Al-Taher, É. Pfeifer, 
E. Kálmán, 17th International Corrosion Congress 2008: 
Corrosion Control in the Service of Society 4, 2631 (2009). 
7. L. Románszki, J. Telegdi, E. Kálmán, Colloid. Surface. A 
321, 20 (2008). 
8. L. Románszki, J. Telegdi, E. Kálmán, Proceedings of 6th 
International Conference of PhD students. Natural Sci-
ences, 97 (2007). 
9. J. Telegdi, F. Al-Taher, L. Románszki, E. Kálmán, Pro-
ceedings of the 3rd International Conference on Technolog-
ical Advances of Thin Films & Surface Coatings: THIN-
FILMS 2006, 1 (2006). 
10. L. Románszki, J. Telegdi, L. Nyikos, Stud. Univ. Babeş–
Bolyai Chem. LVII, 191 (2012). 
11. W.A. Zisman, Ind. Eng. Chem. 55, 19 (1963). 
12. A.B.D. Cassie, S. Baxter, Trans. Faraday Soc. 40, 546 
(1944). 
13. R. Tadmor, Langmuir 20, 7659 (2004). 
14. A.W. Neumann, R.J. Good, C.J. Hope, M. Sejpal, J. Col-
loid. Interf. Sci. 49, 291 (1974). 
15. C.J. van Oss, R.J. Good, M.K. Chaundhury, Langmuir 4, 
884 (1988). 
 


Contact Angle Measurement is an Efficient Tool for the Characterization of Corrosion Pro-tection Nanolayers on Copper Alloys and Stainless Steel

Electronic Sumy State University Institutional Repository

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 2 No 1, 01PCSI04(3pp) (2013)   2304-1862/2013/2(1)01PCSI04(3) 01PCSI04-1  2013 Sumy State University Contact Angle Measurement is an Efficient Tool for the Characterization of Corrosion Pro-tection Nanolayers on Copper Alloys and Stainless Steel  L. Románszki1,*, M. Mohos1,†, J. Telegdi1,2,‡, L. Nyikos1,§  1 Department of Interfaces and Surface Modification, Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Pusztaszeri út 59–67., 1025 Budapest, Hungary 2 Institute of Media Technology and Light Industry, Faculty of Light Industry and Environmental Engineering, Óbuda University, Doberdó u. 6., 1034 Budapest, Hungary  (Received 19 April 2013; published online 29 August 2013)   With the advent of the nano-era, a pronounced interest in the nanolayers has emerged. The develop-ment of more and more sophisticated measurement devices and techniques made possible the visualiza-tion, characterization and investigation of nanolayers. However, there exists a variety of simple, old means which should not be despised either. In this work, the use of contact angle measurement as a simple, fast, inexpensive and accessible tool for the study of surfaces with and without nanolayers is demonstrated. Furthermore, it is evidenced that in contrast to its simplicity, contact angle measurement can address sur-prisingly complex questions and give proper answers to these.  Keywords: Nanolayer, Microbiologically Influenced Corrosion, Contact Angle, Aluminium Brass, Copper-Nickel, Stainless Steel, Self-assembled Monolayers.    PACS numbers: 81.65.Kn, 81.65.Cf, 64.75.Yz, 81.65.Cf                                                             * romanszki.lorand@ttk.mta.hu † mohos.miklos@ttk.mta.hu ‡ telegdi.judit@ttk.mta.hu § nyikos.lajos@ttk.mta.hu 1. INTRODUCTION  Aluminium brass (Al-brass), copper nickel 70/30 (CuNi) [1] and stainless steel 304 (SS) [2] are im-portant alloys in the energy sector. Due to their good heat conductivity and corrosion resistance, the former two are often used as materials of the cooling circuits of power plants operating with seawater as a cooling agent, while SS is a common material of fresh water tubings. In the presence of microorganisms, all these alloys suffer, to some extent, from biofouling and the conse-quent microbiologically influenced corrosion. Means to protect these alloys include dosage of biocides to control the growth of microorganisms and inhibitors for the corrosion protection. However, none of these are always successful. In severe cases, the developed thick biofilm can only be removed by manual cleaning, and during the maintenance shutdown of complete power plant blocks may become unavoidable [3–5]. Ultrathin organic protection layers, such as self-assembled monolayers (SAMs) and Langmuir–Blodgett films have been proven efficient in laboratory experi-ments against both the corrosion itself and the adhe-sion of microorganisms [6–9]. However, their reduced stability in aqueous environment set a limit to their industrial applicability [10]. In the coating industry, a proper pretreatment of the respective surface to be pro-tected is the prerequisite of the success of the coating procedure and the performance of the protection layer. However, thorough cleaning is often time consuming and costly.  Similarly, in laboratory experiments with SAMs, surface pretreatment may be an important, but circui-tous process step. It is therefore desirable to investi-gate the necessity of it. Contact angle (CA) measurement is a basic tool to characterize surfaces. In spite of that it offers much useful information to be extracted from, generally it is applied to serve rather modest purposes only, such as differentiation between a hydrophobic and a hydro-philic surface. Through our experiments, we attempted to answer the question whether CA measurements could be used in a more efficient way in order to obtain information about the success of the nanocoating procedure and the stability of the prepared layer, especially in conjunction with the pretreatment of the substrate surface.   2. EXPERIMENTAL  Aluminium brass, copper-nickel and stainless steel alloy specimens were of 10×12 mm2 dimension, and cut from standardized tubes [1–3], therefore being curved, with approx. 12.7 mm (0.5 in) radius of curvature. Octadecanoyl hydroxamic acid (C18N) was synthe-sized from hydroxylamine and the appropriate acyl chloride. Octadecyl phosphonic acid (C18P) was synthe-sized in a Michaelis–Arbusov reaction. The products were re-crystallized and characterized by melting points, elemental analysis, infrared spectroscopy and thin layer chromatography. As substrate cleaning, 10 min. sonication in spectro-scopic grade acetone was applied, occasionally complet-ed by 20 min. cleaning in ozone generated under an UV lamp. SAM coatings were prepared by dipping the pre-treated metal samples into 2.0 mM solutions of the film forming compounds (C18N, respectively C18P) in chlo- L. ROMÁNSZKI, M. MOHOS, J. TELEGDI, L. NYIKOS PROC. NAP 2, 01PCSI04 (2013)   01PCSI04-2 roform, dichloromethane, or tetrahydrofurane. Dipping times were 1, 5 and 24 h in the case of the alloys. The coated samples were rinsed with the respective solvent in order to remove non-specifically bond excess material and were dried in air or in a stream of nitrogen. The alloy samples, with and without coatings, were characterized by their advancing and receding CAs. Static sessile drop measurements were carried out us-ing a home-built measurement device equipped with a Hamilton micropipette and a CCD camera. For the dy-namic Wilhelmy-type CA measurements a digital sur-face tensiometer (Nima) was used. Samples were auto-matically dipped into and pulled out from water with a rate of 10 mm/s, while the apparent weight change of the target sample was registered. The CAs were re-trieved by inputting the cross sectional dimensions of the samples and the surface tension of the water. Ul-trapure water (MilliQ) was used as a measurement liq-uid in both cases. A stability test of the SAMs in flowing water was conducted for 2 weeks. Dynamic CAs were measured before and after the test. In this latter case the samples were first thoroughly dried.  3. RESULTS AND DISCUSSION  Dynamic CA measurements of as-received and cleaned samples showed the effect of the cleaning pro-cedure (Fig. 1). Al-brass samples exhibited higher ad-vancing and receding CAs than CuNi samples, which exhibited higher values than SS samples, both in as-received and in cleaned  state. In this same order, the effect of cleaning became more and more pronounced, from about 20° advancing CA difference in the case of Al-brass, 30° in the case of CuNi and 35° in the case of SS. Similarly, the receding CA differences were 5, 15 and 16° for the three alloy types, respectively.    Fig. 1 – Advancing and receding CAs of as-received vs. cleaned alloy samples, averaged for 4 parallel sample of each type, measured in 6 consecutive dipping cycles in a Wilhelmy-type dynamic measurement  The change in the CAs during the consecutive dip-ping cycles was spectacular (Fig. 2). In the case of the as-received samples, advancing CAs initially increased, while receding CAs monotonously decreased in each new cycle. Contrarily, cleaned samples showed not only lower CAs, but also much more stable ones. When the effect of the cleaning on the C18N-SAM formation was studied, it was found that after the com-plementary UV cleaning step the static CA of all alloy types decreased approx. to the same value (32-35°), as an indication of a more pronounced hydrophilicity. When SAM preparation was carried out after this UV step, the high CAs on Al-brass and SS (90°) indicated the formation of a SAM. However, in the case of Al-brass, SAM preparation proved to be successful also when performed after a simple acetone-cleaning (CA  92°), apparently not effective in the case of SS (CA  66°). Wilhelmy-type CA measurement can be used in or-der to learn about the short-term stability of such nano-coatings, as suggested by our results (Fig. 4). When sub-tracting the values of advancing CAs of the same sam-ples obtained in two consecutive immersion cycles, a few degrees differences can be noticed, as already shown in Fig. 2. The difference depends on the alloy type and has a large statistical spread, but it is generally negative, i.e. the surfaces become slightly more hydrophilic after each new immersion step, as an indication that the structure of SAM layers is slightly altered in water.    Fig. 2 – Advancing and receding CAs of as-received vs. cleaned alloy samples in the consecutive dipping cycles of the Wilhelmy-type dynamic measurement  When these differences are plotted as a function of the preparation time of the SAM, a reasonable trend becomes obvious: the longer the initial SAM preparation time was (the time allowed the molecules to adopt the best possible arrangement on the surface), the lower this difference is during the immersions. The larger differences are usually measured for the uncoated con-trol samples, as obviously the wetting of these ones pro-gresses with the fastest rate.      Ac             Ac+UV          Ac+SAM    Ac+UV+SAM Al-brass            63                  32      92           90 SS              56                 35      66           90  Fig. 3 – The effect of surface cleaning on the C18N-SAM for-mation, as revealed by static CAs (°) of different alloy surfac-es. Ac: cleaned in acetone; Ac+UV: cleaned in acetone, fol-lowed by an UV-cleaning step; Ac+SAM: SAM formation after acetone- cleaning; Ac+UV+SAM: SAM formation after ace-tone- and UV-cleaning  CONTACT ANGLE MEASUREMENT IS AN EFFICIENT TOOL… PROC. NAP 2, 01PCSI04 (2013)   01PCSI04-3 In accord with these above facts, CA measurement proved to be effective also in the correct estimation of the long-term stability of these nanolayers. Layers pre-pared for 1, 5 and 24 h respectively were measured in three consecutive cycles both before and after a two week long stability test in flowing water. Taking the after/before advancing CA differences in any measure-ment cycle, we found very drastic CA decrease after the test, indicating a pronounced hydrophilicity originating from a pronounced layer alteration in the water (Fig. 5).    Fig. 4 – Short-term stability of C18N-SAM coatings: wetting during Wilhelmy CA measurement cycles (advancing CA dif-ferences between the second and the first immersion cycles) in function of allowed self-assembly time  However, this lowering of the CA showed very strong dependence on the SAM preparation time. The layers allowed to build up for 1 h only showed the larg-est CA fall (about 45-50°), the ones prepared for 5 h showed only 40°, while the ones assembled for 24 h showed only 25-30°. We found it particularly spectacu-lar that these simple CA measurements could lead to the same conclusion as our previous, more sophisticated reflection absorption infrared spectroscopy (RAIRS) and sum frequency generation spectroscopy (SFG) investiga-tions [10]. This fact points out the hidden possibilities laying in the CA measurements.    Fig. 5 – Long-term stability of C18P-SAM coated Al-brass samples for 2 weeks in flowing water. After-before advancing CA differences in the 1st (light grey), 2nd (grey) and 3rd im-mersion cycles (dark grey) as function of self-assembly time  4. CONCLUSIONS  The main conclusion of this work is that, as demon-strated above, simple, fast, inexpensive and accessible CA measurements can provide answers to surprisingly deep questions.  ACKNOWLEDGEMENTS  József Maráczi is acknowledged for the construction of the sessile drop CA goniometer. The research leading to these results has received funding from the Europe-an Community's Seventh Framework Programme FP7/2007–2013 under grant agreement n°238579.   REFERENCES  1. Standard specification for copper and copper-alloy seam-less condenser tubes and ferrule stock, Designation: B 111 – 98 (Reapproved 2004) (ASTM International: 2004). 2. Standard specification for welded austenitic steel boiler, superheater, heat-exchanger, and condenser tubes, Desig-nation: A 249/A 249M – 04 (ASTM International: 2004). 3. P. Cristiani, Appl. Therm. Eng. 25, 2630 (2005).   4. P. Cristiani, G. Perboni, A. Debenedetti, Electrochim. Acta 54, 100 (2008). 5. Techniques for corrosion monitoring (Ed. L. Yang) (Cam-bridge: Woodhead Publishing Ltd.: 2008). 6. J. Telegdi, L. Románszki, F. Al-Taher, É. Pfeifer, E. Kálmán, 17th International Corrosion Congress 2008: Corrosion Control in the Service of Society 4, 2631 (2009). 7. L. Románszki, J. Telegdi, E. Kálmán, Colloid. Surface. A 321, 20 (2008). 8. L. Románszki, J. Telegdi, E. Kálmán, Proceedings of 6th International Conference of PhD students. Natural Sci-ences, 97 (2007). 9. J. Telegdi, F. Al-Taher, L. Románszki, E. Kálmán, Pro-ceedings of the 3rd International Conference on Technolog-ical Advances of Thin Films & Surface Coatings: THIN-FILMS 2006, 1 (2006). 10. L. Románszki, J. Telegdi, L. Nyikos, Stud. Univ. Babeş–Bolyai Chem. LVII, 191 (2012). 11. W.A. Zisman, Ind. Eng. Chem. 55, 19 (1963). 12. A.B.D. Cassie, S. Baxter, Trans. Faraday Soc. 40, 546 (1944). 13. R. Tadmor, Langmuir 20, 7659 (2004). 14. A.W. Neumann, R.J. Good, C.J. Hope, M. Sejpal, J. Col-loid. Interf. Sci. 49, 291 (1974). 15. C.J. van Oss, R.J. Good, M.K. Chaundhury, Langmuir 4, 884 (1988).  

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Contact Angle Measurement is an Efficient Tool for the Characterization of Corrosion Pro-tection Nanolayers on Copper Alloys and Stainless Steel

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