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T he three-Dimensional Ion Implantation technique (3DII) causes ions to collide with a solid surface in a perpendicular way regardless of the geometry of the solid (Khvesyuk & Tsygankov, 1997; Dougar-Jabon, Dulce-Moreno & Tsygankov, 2002). The steel AISI SAE 4140 has been used as substrate because of its wide use in the transport of oil industry, the specimens of steel underwent surface modification with Titanium ions (Ti) and the combined ions of titanium and nitrogen (Ti+N), with an energy of 10keV for 5min and 10min. The superficially modified and unmodified specimens were characterized by Electrochemical Impedance Spectroscopy (EIS), noting among the most outstanding results the electrochemical double layer system capacitive characteristics under all tested conditions, the best corrosion performance was obtained for implanted substrates with Ti ions for 10min, having a charge transfer resistance much higher than those implanted with Ti+N and the non-implanted. Additionally, it was determined that all the implanted systems can be simulated by using one equivalent circuit with a constant phase element instead of a capacitor and the non implanted substrate from day 15 can be simulated through another equivalent circuit.
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CHARACTERIZATION OF THE LOW ALLOY STEEL MODIFIED SUPERFICIALLY WITH IONS OF TITANIUM AND NITROGEN
CT&F - Ciencia, Tecnología y Futuro - Vol. 6 Num. 3 Jun. 2016 135
CHARACTERIZATION OF THE LOW ALLOY
STEEL MODIFIED SUPERFICIALLY WITH IONS
OF TITANIUM AND NITROGEN
Ely-Dannier Valbuena-Niño1-2*, Linda Gil3, Luis Hernández-Molina3, José-José Barba-Ortega4
and Valeriy Dugar-Zhabon2
1 Universidad Politécnica de Madrid, Madrid, España
2Universidad Industrial de Santander, Bucaramanga, Colombia
3Universidad Nacional Experimental Politécnica, Puerto Ordaz, Venezuela
4Universidad Nacional de Colombia, Bogotá, Colombia
e-mail: deydannv@gmail.com
(Received: Feb. 03, 2016; Accepted: May 31, 2016)
*To whom correspondence should be addressed
CT&F - Ciencia, Tecnología y Futuro - Vol. 6 Num. 3 Jun. 2016 Pag. 135 - 146
The three-Dimensional Ion Implantation technique (3DII) causes ions to collide with a solid surface in a
perpendicular way regardless of the geometry of the solid (Khvesyuk & Tsygankov, 1997; Dougar-Jabon,
Dulce-Moreno & Tsygankov, 2002). The steel AISI SAE 4140 has been used as substrate because of its
wide use in the transport of oil industry, the specimens of steel underwent surface modification with Titanium
ions (Ti) and the combined ions of titanium and nitrogen (Ti+N), with energy of 10keV for 5min and 10min.
The superficially modified and unmodified specimens were characterized by Electrochemical Impedance Spec-
troscopy (EIS), noting among the most outstanding results the electrochemical double layer system capacitive
characteristics under all tested conditions, the best corrosion performance was obtained for implanted substrates
with Ti ions for 10min, having a charge transfer resistance much higher than those implanted with Ti+N and
the non-implanted. Additionally it was determined that all the implanted systems can be simulated by using
one equivalent circuit with a constant phase element instead of a capacitor and the non implanted substrate
from day 15 can be simulated through another equivalent circuit.
ABSTRACT
How to cite: Valbuena-Niño, E. D., Gil, L., Hernández-Molina, L., Barba-Ortega, J. J. & Dugar-Zhabon, V. (2016).
Characterization of the low alloy steel modified superficially with ions of titanium and nitrogen. CT&F - Ciencia, Tecnología
y Futuro, 6(3), 127-138.
CARACTERIZACIÓN DEL ACERO DE BAJA ALEACIÓN MODIFICADO
SUPERFICIALMENTE CON IONES DE TITANIO Y NITRÓGENO
CARACTERIZAÇÃO DO AÇO DE BAIXA LIGA ALTERADO
SUPERFICIALMENTE COM IONES DE TITÂNIO E NITROGÊNIO
ISSN (Print) 0122-5383
ISSN (Online) 2382-4581
Journal of oil, gas and alternative energy sources
Keywords: Chromium-molybdenum steels, Corrosion, Spectroscopy ionic implantation.
CT&F - Ciencia, Tecnología y Futuro - Vol. 6 Num. 3 Jun. 2016
ELY-DANNIER VALBUENA-NIÑO et al.
136
L
a técnica de implantación iónica tridimensional (3DII) consigue que los iones a implantar colisionen
perpendicularmente con la superficie sin importar la geometría del sólido (Khvesyuk & Tsygankov, 1997;
Dougar-Jabon et al., 2002). Se ha usado un acero de herramientas AISI SAE 4140 como sustrato
por su amplio uso en la industria del transporte de hidrocarburos. Las probetas de acero se sometieron a
la modificación superficial con iones Titanio (Ti) y Titanio+Nitrógeno (Ti+N) a energía de 10keV durante
5min y 10min. Los sustratos modificados y no modificados superficialmente fueron caracterizados mediante
la técnica de espectroscopia de impedancia electroquímica (EIS), observando entre los resultados más
resaltantes que la doble capa electroquímica del sistema en estudio presenta características capacitivas en
todas las condiciones evaluadas, donde el mejor desempeño frente a la corrosión lo presentan los sustratos
implantados con iones de Ti durante 10min, debido a que poseen una resistencia a la transferencia de carga
mucho mayor que los implantados con iones de Ti+N y los no implantados. Adicionalmente se determinó
que todos los sistemas implantados pueden ser simulados mediante el uso de un circuito equivalente, el cual
posee un elemento de fase constante en lugar de un capacitor y que el sustrato sin implantar a partir del día
de inmersión 15 se puede simular a través de otro circuito equivalente diferente.
A técnica de implantação iônica tridimensional (3DII) consegue que os iones a serem implantados
colidam perpendicularmente com a superfície sem importar a geometria do sólido (Khvesyuk &
Tsygankov, 1997; Dougar-Jabon et al., 2002). Foi usado um aço de ferramentas AISI SAE 4140
como substrato sendo que ele é extensivamente utilizado na indústria de transporte de hidrocarbonetos.
Os espécimenes de aço foram submetidos à alteração superficial com iones de Titânio (Ti) e Titânio +
Nitrogênio (Ti+N) com energia de 10keV durante 5 min e 10 min. Os substratos alterados e não alterados
superficialmente foram caracterizados mediante a técnica de espectroscopia de impedância eletroquímica
(EIS), verificando-se entre os resultados mais importantes que a dupla capa eletroquímica do sistema em
estudo apresenta características em todas as condições avaliadas, onde o melhor desempenho diante da
corrosão é conseguido com os substratos implantados com iones de Ti durante 10 min, por conta deles
possuírem uma resistência à transferência de carga muito maior do que aqueles implantados com iones de
Ti+N e com os não implantados. Adicionalmente, determinou-se que todos os sistemas implantados podem
ser simulados mediante o uso de um circuito equivalente, que possui um elemento de fase constante ao invés
de um capacitor e que o substrato sem implantar a partir do dia de imersão 15 pode ser simulado através
de outro circuito equivalente diferente.
Palabras clave:
Aceros cromo-molibdeno, Corrosión, Espectroscopia, Implantación iónica.
Palavras-chave: Aços cromo-molibdênio, Corrosão, Espectroscopia, Implantação iônica.
RESUMEN
RESUMO
CHARACTERIZATION OF THE LOW ALLOY STEEL MODIFIED SUPERFICIALLY WITH IONS OF TITANIUM AND NITROGEN
CT&F - Ciencia, Tecnología y Futuro - Vol. 6 Num. 3 Jun. 2016 137
1. INTRODUCTION
The low alloy tool steel AISI SAE 4140 contains
chromium, molybdenum and manganese as main
alloying elements, which confers high resistance to
fatigue, abrasion, impact and torsion, in addition, it
can achieve high hardness when processed under a
suitable heat treatment. The chromium content provides
a good resistance to pitting and molybdenum ensures
high strength and uniform hardness. Common uses of
tool steel AISI SAE 4140 mainly include industrial
applications; small pinions, scissors, high strength
screws, guides, cam followers, reducing axes, chisels,
blocks of plates for ller brackets, punch holder for
structural parts, clamps, gauges moulds, brake dice
templates, and high strength parts (Peña et al., 2009;
V. Niño & Dougar-Jabon, 2006; Valbuena-Niño, Dulcé
& Dugar-Zhabon, 2010).
In the energy sector, wear and corrosion are main
causes of failure of industrial parts and tools. AISI
SAE 4140 steel is not exempted from suffering these
phenomena, although the alloy contains chromium, it
is not enough to achieve properties of stainless steels. A
common way or alternative to improve the resistance to
corrosion and wear is to modify the surface by applying
a coating (Peña et al., 2009; V. Niño & Dougar-Jabon,
2006; Valbuena-Niño et al., 2010).
Ion implantation is a process by which ions are
accelerated to make them collide with a solid surface due
to the kinetic energy acquired, these ions penetrate into
the crystal lattice causing a series of mutually related
processes that alter the physical and chemical behavior of
the surface. The 3DII allows ions collide perpendicularly
with the solid surface regardless geometry, preserving
the monoenergetic characteristics of ions, which offers
signicant advantages over conventional methods of
implantation (Khvesyuk & Tsygankov, 1997; Dougar-
Jabon et al., 2002).
3DII technique is performed at very low pressures
(about 0.6Pa), which decreases the risk of contamination
and the plasma generated in the high voltage discharge
is self sustained (not need support plasma (Khvesyuk
& Tsygankov, 1997; Dougar-Jabon et al., 2002) that
behaves as an ion source, which acquire energy of
kilo-electron-volts (keV) range (Dulcé-Moreno et al.,
2011; Parada-Becerra et al., 2012; V. Niño, Peña,
Reyes & Dugar-Zhabon, 2013; V. Niño, Salinas, Peña
& Chinchilla, 2011). This research focuses on studying
the electrochemical interaction surface-electrolyte of the
steel AISI SAE 4140 implanted and non-implanted with
Ti and Ti+N ions, using the Electrochemical Impedance
Spectroscopy (EIS) technique.
2. METHODOLOGY AND MATERIALS
The substrates of steel AISI SAE 4140 with disk
geometry were superficially implanted by hybrid
discharges, high voltage and electric arc at low pressures
with Ti and Ti+N ions for 5 and 10min to voltage
of 10keV (Dugar-Zhabon, Dulcé-Moreno, Garnica-
Villamizar & Valbuena-Niño, 2012; Tsygankov et a.,
2011; V. Niño et al., 2012), taking into account the
same procedure conducted in the previous research
(Hernández et al., 2014).
Electrochemical tests were performed with a
potentiostat/galvanostat Gamry Interface 1000 and an
electrochemical cell of three electrodes, comprising
a bubbler, pH and temperature sensor, the working
electrode (anode), against graphite electrode (cathode),
a calomel reference electrode and 3.5%wt NaCl as
electrolyte. Samples were immersed for 28 days and
analyzed at day 0, 7, 15, 21 and 28, by EIS technique in
100kHz to 10mHz frequency range. Disturbance voltage
was 10mV.
3. RESULTS AND DISCUSSION
The EIS is a non-destructive technique used to char-
acterize the behavior of an electrochemical electrode-
electrolyte interface, in this technique a harmonic volt-
age signal with amplitude on the order of millivolts and
whose frequency f is applied generally within a range
from several millihertz to some tens of kilohertz (Gil,
Jiménez & Staia, 2006), the current owing through the
circuit is detected and recorded to analyze and interpret
the complex impedance of the system (Gil et al., 2006).
Figure 1 show the Nyquist plot of the substrate in steel
AISI SAE 4140 non-implanted and immersed from 0
to 28 days in brind solution.
Based on Figure 1, it becomes evident that with a
CT&F - Ciencia, Tecnología y Futuro - Vol. 6 Num. 3 Jun. 2016
ELY-DANNIER VALBUENA-NIÑO et al.
138
15-day immersion, the non-implanted samples behavior
of the impedance at low frequencies corresponds to
a pseudo-inductive effect, possibly caused by the
reactions of adsorption/reabsorption of chemical
species in the metal surface resulting in a change in the
corrosion rate at that frequency (Escobar et al., 2013).
This phenomenon is not seen in the rst seven days of
immersion.
Next in Figure 2, the Nyquist plot corresponding to
the specimens implanted with Ti+N to 10kV for 5min
is presented. The occurrence of one semicircle in the
Nyquist plot indicates that the electrochemical reactions
occur with only one time constant τ (Escobar et al.,
2013). Also a reduction of the semicircle diameter with
respect to day 0 can be seen, from which a decrease in
the charge transfer resistance Rct can be veried after
a prolonged immersion.
Figure 4 shows the Nyquist plots for samples
implanted with Ti ions to 10kV for 5 and 10min. The
implantation condition of 10min has the singularity that
0.000
0.000
50.00
100.0
20.00 40.00 60.00 80.00 100.0 120.0 140.0 160.0 180.0 200.0 220.0 240.0 260.0
- Z imag (ohm*cm
2
)
Z real (ohm*cm
2
)
0 days 28 days 7 days 15 days 21 days
Figure 1. Nyquist plot for non-implanted substrates at different immersion times studied.
Figure 2. Nyquist plot for specimens implanted with Ti+N 10kV for 5min, at different immersion times studied.
0.000 200.0 400.0 600.0
0.000
100.0
200.0
300.0
- Z imag (ohm*cm
2
)
Z real (ohm*cm
2
)
0 days 7 days 15 days 21 days 28 days
CHARACTERIZATION OF THE LOW ALLOY STEEL MODIFIED SUPERFICIALLY WITH IONS OF TITANIUM AND NITROGEN
CT&F - Ciencia, Tecnología y Futuro - Vol. 6 Num. 3 Jun. 2016 139
in the 28th immersion day the semicircle was enlarged
and this allows us to observe an increased resistance to
charge transfer at the end of the time evaluated in this
study.
Before fitting the equivalent circuits, the data
was validated using the Kramers-Kronig relations,
always obtaining excellent Xi squared values <10-3.
The equivalent circuit simulation obtained for both
implanted and non-implanted surfaces was performed
with the Simplex method in the software V6.11 Gamry
Echem Analyst, which simulates all the implanted
systems behavior through one simple equivalent electric
circuit and the non implanted substrate behavior from
day 15 through another equivalent circuit; Figure 5
provides details on the two types of circuits that were
used for the simulation. The simulation had Xi
2<10-3
(goodness of the t) in almost all the conditions studied.
In circuit (b) CPEads and Rads were used to simulate
the pseudo-inductive behavior possibly caused by the
reactions of adsorption/reabsorption of chemical species
in the metal surface. Figure 6 shows some of the curve
tting for Kramers-Kronig validation and equivalent
circuit simulation.
Tables 1 to 5 provide the parameters corresponding
to the EIS test applied to steel AISI SAE 4140 modied
and not modied supercially with Ti and Ti+N ions.
Note that the alpha parameter α indicates that the
electrochemical double layer may have a resistive or
capacitive behavior, therefore in almost all conditions
studied, the electrochemical double layer formed on
the interface between samples and the surrounding
electrolyte, has a capacitive characteristic because the
values of α were always higher than 0.5.
Figures 7 and 8 show that the capacitance of the
electrochemical double layer (CPE) in all the samples
increases with immersion time; one order of magnitude
for the reference substrate (not modied supercially)
and up to three orders of magnitude for implanted
substrates, note that in the samples implanted with Ti
ions for 10min a sudden drop in capacitance is recorded
in the 28th day of trial, which reaches a decrease of 9
orders of magnitude.
Increased capacitance is possibly due to the
penetration of electrolytes through the corrosion products
that are formed in the surface of the specimens (Escobar
et al., 2013). Other authors describe the increase in
capacitance as the result of an increased porosity of the
layers of the corrosion products presented (Cottis &
Turgoose, 1999), whereas the decreased capacitance of
the Ti substrate implanted with ions during 10min on
the 28th day of immersion may be related to changes
Figure 3. Nyquist plots of the samples implanted with Ti+N to 10kV for 10min (a) for all immersion times studied, (b) to
observe Zoom detail Nyquist curves.
0.000
0.000 100.0 200.0
0.000
50.00
100.0
150.0
1.000k 2.000k 3.000k
0.000
500.0
1.000k
- Z imag (ohm*cm
2
)
Z real (ohm*cm
2
)
(a)
(b)
0 days 7 days 15 days 21 days 28 days
CT&F - Ciencia, Tecnología y Futuro - Vol. 6 Num. 3 Jun. 2016
ELY-DANNIER VALBUENA-NIÑO et al.
140
200.0M 200.0K
1.000K
1.000K
0.000
0.000
0.000 1.000K
0.000 500.0
500.0
1.000K
30.00K
25.00K
20.00K
15.00K
10.00K
5.00K
5.00K 10.00K 15.00K20.00K25.00K30.00K35.00K40.00K45.00K50.00K55.00K60.00K
0.00
0.00
100.0M
0.000
0.000 200.0M 400.0M 500.0M
Z real (ohm*cm
2
)
(a) (b)
(c) (d)
Z real (ohm*cm
2
)Z real (ohm*cm
2
)
Z real (ohm*cm
2
)
0 days 7 days 15 days 21 days 28 days
Figure 4. Nyquist plots for samples implanted with Ti 10kV (a) for 10min, (b) for 5min, (c) Zoom of insert (a), (d) Zoom of insert (c).
Table 1. EIS corresponding values of the parameters for the reference substrate.
Figure 5. (a) Equivalent circuit used to simulate the implanted samples, and non implanted samples immersed 0 days and 7 days. (b)
Circuit used to simulate the behavior of the non implanted substrate from 15 to 28 days of immersion..
(a) (b)
R.E
R.E Rs
CPEdl CPEads
CPEdl
alpha alpha beta
Rct Rct Rads
W.E.
W.E.
Rs
Rct
(ohm*cm
2
)
CPE
(S*s
a
)/(cm
2
)
α
Xi squared
KramersKronig
Xi
2
244.30
5.88E-A
9.04E-1
3.10E-2
1.51E-3
51.34
7.13E-04
8.83E-01
1.84E-03
9.10E-04
62.19
1.02E-03
8.25E-01
3.42E-03
2.07E-03
37.67
8.09E-04
8.69E-01
1.82E-02
1.10E-02
0.51
2E-05
4E-03
64.61
1.05E-03
8.11E-01
2.15E-03
1.47E-03
8.61
4E-05
1E-02
1.49
2E-05
4E-03
0.77
1E-05
3E-03
2.48
4E-06
7E-06
Parameter
Days
0 7 15 21 28±error ±error ±error ±error ±error
CHARACTERIZATION OF THE LOW ALLOY STEEL MODIFIED SUPERFICIALLY WITH IONS OF TITANIUM AND NITROGEN
CT&F - Ciencia, Tecnología y Futuro - Vol. 6 Num. 3 Jun. 2016 141
Table 2. EIS corresponding values of the parameters for samples implanted with Ti+N for 5min
Table 3. EIS corresponding values of the parameters for samples implanted with Ti+N for 10min.
Table 4. EIS corresponding values of the parameters for samples implanted with Ti for 5min.
Rct
(ohm*cm
2
)
CPE
(S*s
a
)/(cm
2
)
α
Xi squared
KramersKronig
Xi
2
620.90
3.99E-04
8.64E-01
2.67E-02
6.21E-04
236.30
2.28E-03
7.99E-01
6.03E-04
1.51E-04
188.30
4.14E-03
7.23E-01
6.98E-03
7.12E-03
221.60
7.23E-03
8.57E-01
3.44E-03
1.26E-03
2.24
6E-05
2E-03
212.90
1.19E-02
8.16E-01
1.71E-03
1.35E-03
2.85
1E-04
2E-03
1.68
4E-05
2E-03
2.31
3E-05
2E-03
5.94
5E-06
5E-03
Parameter
Days
0 7 15 21 28±error ±error ±error ±error ±error
Rct
(ohm*cm
2
)
CPE
(S*s
a
)/(cm
2
)
α
Xi squared
KramersKronig
Xi
2
2415.00
9.00E-05
8.76E-01
8.03E-02
9.71E-04
226.90
1.35E-03
8.22E-01
5.68E-03
2.73E-04
144.50
1.95E-03
8.72E-01
8.92E-03
3.30E-03
190.00
4.83E-03
1.00E+00
5.73E-02
5.64E-02
2432.00
5E-05
2E-03
316.60
7.31E-03
7.24E-01
1.95E-03
9.42E-05
4270.00
6E-05
2E-03
1306.00
2E-05
2E-03
2036.00
2E-05
2E-03
21.62
9E-07
1E-03
Parameter
Days
0 7 15 21 28±error ±error ±error ±error ±error
Rct
(ohm*cm2)
CPE
(S*sa)/(cm2)
α
Xi squared
KramersKronig
Xi2
325200.00
5.98E-06
8.11E-01
4.24E-02
7.52E-04
2146.00
1.86E-03
7.21E-01
2.38E-02
2.96E-04
1611.00
3.57E-03
6.70E-01
1.18E-02
6.66E-05
3420.00
3.72E-03
7.09E-01
1.14E-02
4.45E-05
128.40
2E-05
1E-03
4567.00
4.19E-03
7.26E-01
1.92E-03
3.26E-05
277.80
3E-05
2E-03
36.92
2E-05
1E-03
52.16
1E-05
2E-03
3289.00
4E-08
9E-04
Parameter
Days
0 7 15 21 28±error ±error ±error ±error ±error
Rct
(ohm*cm
2
)
CPE
(S*s
a
)/(cm
2
)
α
Xi squared
KramersKronig
Xi
2
67940.00
2.98E-05
8.85E-01
3.76E-02
2.86E-04
1898.00
1.40E-03
8.90E-01
5.24E-02
4.32E-04
1828.00
2.55E-03
6.68E-01
5.43E-03
2.17E-04
1578.00
3.44E-03
6.53E-01
8.37E-02
5.60E-05
38.19
3E-05
2E-03
5.78E+08
1.10E-11
9.68E-01
5.90E-03
4.30E-04
4.7E+06
2E-13
1E-03
39.46
2E-05
2E-03
20.59
1E-05
1E-03
734.10
2E-07
9E-04
Parameter
Days
0 7 15 21 28±error ±error ±error ±error ±error
Table 5. EIS corresponding values of the parameters for samples implanted with Ti for 10min.
CT&F - Ciencia, Tecnología y Futuro - Vol. 6 Num. 3 Jun. 2016
ELY-DANNIER VALBUENA-NIÑO et al.
142
in morphology of corrosion products layers formed on
the surface possibly becoming a homogeneous passive
layer (Cottis & Turgoose, 1999). The resistance to
charge transfer for the conditions studied, except for the
implantation with Ti for 10min, has the characteristic of
starting in a maximum and then decrease and stabilize
1 order of magnitude below the initial value for the
substrate, 2 orders of magnitude below the initial value
to the Ti for 5min and Ti+N for 10min, and decrease 3
times under baseline conditions for the implantation of
Ti+N for 5min.
The samples implanted with Ti ions for 10min have
a different behavior, since the resistance to charge
transference increases about 5 orders of magnitude
between day 21 and day 28 and remains up to 4 orders of
magnitude above the initial value. Increased resistance
to charge transference indicates that the corrosion
process is disadvantageous (Flores-Merino & Paucar-
Cuba, 2003; Cabrera-Sierra, Marín-Cruz & González,
2007; Galván et al., 2016; Chang, 2016) possibly due to
the presence of a passive lm that becomes more stable
in time (Galván et al., 2016; Vasilescu et al., 2015).
The open circuit corrosion potential is one of the
300
250
200
150
100
50
0
0 5 10 15 20 25 30
1.20E-03
1.00E-03
6.00E-04
4.00E-04
2.00E-04
0.00E+00
8.00E-04
Rct (ohm*cm
2
)
CPE (S*s
a
/cm
2
)
Days
Rct CPE
Figure 7. Resistance to charge transfer and capacitance versus
immersion time for the reference substrate.
Figure 8. Resistance to charge transfer and capacitance versus immersion time for substrates implanted with
(a) Ti+N for 5min, (b) Ti+N for 10min, (c) Ti for 5min, and (d) Ti for 10min.
Rct CPE
1.00E+06 1.00E+09
1.00E+08
1.00E+07
1.00E+06
1.00E+05
1.00E+04
1.00E+03
1.00E+02
650
550
450
350
250
150
50
0 5 10 15 20 25 30 0 5 10 15 20 25 30
4.50E-03
4.00E-03
3.50E-03
3.00E-03
2.40E-03
2.00E-03
1.50E-03
5.00E-04
0.00E-00
8.00E-03
7.00E-03
6.00E-03
5.00E-03
4.00E-03
3.00E-03
2.00E-03
1.00E-03
0.00E-00
1.00E-03
4.00E-03
3.50E-03
3.00E-03
2.50E-03
2.00E-03
1.50E-03
1.00E-03
5.00E-04
0.00E-00
1.40E-02
1.20E-02
1.00E-02
8.00E-03
6.00E-03
4.00E-03
2.00E-03
0.00E-00
0 5 10 15 20 25 30 0 5 10 15 20 25 30
1.00E+05
1.00E+04
1.00E+03
1.00E+02
3.00E+03
2.50E+03
2.00E+03
1.50E+03
1.00E+03
5.00E+02
0.00E+00
Rct (ohm*cm
2
)Rct (ohm*cm
2
)
Days Days
Days
(a) (b)
(c) (d)
Days
Rct (ohm*cm
2
)Rct (ohm*cm
2
)
CPE (S*s
a
/cm
2
)
CPE (S*s
a
/cm
2
)
CPE (S*s
a
/cm
2
)
CPE (S*s
a
/cm
2
)
CHARACTERIZATION OF THE LOW ALLOY STEEL MODIFIED SUPERFICIALLY WITH IONS OF TITANIUM AND NITROGEN
CT&F - Ciencia, Tecnología y Futuro - Vol. 6 Num. 3 Jun. 2016 143
tools to nd out the tendency of an electrochemical
system to corrode or not, where higher thermodynamic
potential tendency for low corrosion may take place
and vice versa. Figure 9 shows that at 0 days samples
implanted in all conditions have corrosion potential
between 100 and 140mV higher than the non-implanted
substrate, indicating that implanted samples have a lower
thermodynamic tendency to corrosion as compared to
substrates without implantation. However after 7 days
immersion, there are two subgroups with different
trends, the group formed by the samples implanted
with Ti ions for 5 and 10min, whose potential is above
the corrosion potential of the non-implanted substrate,
meaning it is less prone to corrode. The second subgroup
comprises the specimens implanted with Ti+N ions for
5 and 10min, whose potential is below the corrosion
potential of the substrate of reference, indicating that
the specimens implanted with Ti+N ions have a higher
thermodynamic tendency to corrosion as compared to
the non-implanted substrate.
4. CONCLUSIONS
The EIS spectra of the substrates implanted and
non-implanted presented only one time constant τ,
which allows us to conclude that the implanted ions
do not form a lm as in a coating, but instead they
fully integrate with the substrate, the behavior of the
implanted samples can be simulated by using one
equivalent circuit, which has a constant phase ele-
ment instead of a capacitor, and the behavior of the
non implanted substrates from day 15 to 28 can be
simulated with one equivalent circuit, which has two
constant phase elements instead of two capacitors.
The electrochemical double layer formed on the inter-
face between samples, implanted and non-implanted,
and the surrounding electrolyte, showed a capacitive
behavior, because the values of α obtained from the
EIS test were between 0.5 and 1.
According to the charge transference resistance, all
surfaces implanted have best corrosion resistance
when compared to the non-implanted surface. The
decrease in the capacitance of samples implanted with
Ti ions for 10min and 10kV on the 28th day, may be
related to the changes in morphology due to corro-
sion products and the layers homogeneous passive
characteristics of TiO2 formed on the surface.
According to the open circuit potential measurements
the Ti ions implanted samples have less tendency to
corrode. The Rct of the specimens implanted with
Ti ions showed a higher corrosion resistance than
surfaces implanted with Ti+N and non-implanted.
The best corrosion performance was obtained by
specimens implanted with Ti ions for 10min and
10kV. Further studies will be conducted to analyze
the morphology and composition of the surface and
corrosion product layers before and after immersion,
to conrm the layer passive characteristics.
ACKNOWLEDGEMENTS
The authors thank the FITEK group of the Universidad
Industrial de Santander, Group of Physics Mesoscopic
of the Universidad Nacional de Colombia, CECOB of
the Universidad Nacional Experimental Politécnica
Antonio José de Sucre and DIM-ETSII of the Univeridad
Politécnica de Madrid for the generous collaboration.
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CHARACTERIZATION OF THE LOW ALLOY STEEL MODIFIED SUPERFICIALLY WITH IONS OF TITANIUM AND NITROGEN
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AUTHORS
Ely-Dannier Valbuena-Niño
Afliation: Universidad Politécnica de Madrid - Universidad
Industrial de Santander
Physics, Universidad Industrial de Santander
M.Sc. in Physics, Universidad Industrial de Santander
Ph.D. student in Mechanical Engineering, Universidad Politéc-
nica de Madrid
e-mail: deydannv@gmail.com
Linda Gil
Afliation: Universidad Nacional Experimental Politécnica
Materials Engineering, Mention Metallurgy, Universidad Simón
Bolívar
M.Sc. in Metallurgy and Materials Science, Instituto Venezolano
de Investigaciones Cientícas
Ph.D. in Sciences, Mention Metallurgy and Materials Science,
Universidad Central de Venezuela
e-mail: lindaegil@gmail.com
Luis Hernández-Molina
Afliation: Universidad Nacional Experimental Politécnica
Chemistry technician, Instituto Universitario de Tecnología José
Antonio Anzoátegui
Metallurgical Engineer, Universidad Nacional Experimental
Politécnica Antonio José de Sucre
e-mail: lahernandez@unexpo.edu.ve
José-José Barba-Ortega
Afliation: Universidad Nacional de Colombia
Physics, Universidad Industrial de Santander
M.Sc. in Physics, Universidad Industrial de Santander
Ph.D. in Physics, Universidade Federal de Pernambuco
e-mail: jjbarbao@unal.edu.co
Valeriy Dugar-Zhabon
Afliation: Universidad Industrial de Santander
Physics, Moscow State University
M.Sc. in Physics, Moscow State University
Ph.D. in Physics and Mathematical, Peoples' Friendship Univer-
sity of Russia
e-mail: vdougar@uis.edu.co
CT&F - Ciencia, Tecnología y Futuro - Vol. 6 Num. 3 Jun. 2016
ELY-DANNIER VALBUENA-NIÑO et al.
146
... These interactions with such an aggressive media naturally Several studies have achieved interesting results in the implantation process and its applications in ferrous alloys, demonstrating that it is possible to modify the structural and chemical composition of materials in order to improve its performance in typical aggressive media in engineering applications [12][13][14][15][16][17][18][19][20]. ...
... In Figure 4, are illustrated the Nyquist curves for By comparing the implanted systems in Table 5, it can be seen that the layer resistance Rads was higher in samples implanted with Ti+N than the ones modified with Ti; these findings are likely due to the N implanted, which as [48][49][50]. By comparing the performance of implanted samples and the results in terms of polarization resistance, these results which in good agreement with other authors [17], it allows to conclude that 3DII provide a passive film whose determined thickness and density distributed superficially across the steel samples, which act as a surface barrier or blockage of the active sites of medium carbon steels when beneficial response of the radiation damage of certain materials, exposed to ion implantation was more evident than the chemical effect itself [7, 39,40,53,54]. ...
... a) shows the microstructure of the substrates implanted with Ti, where a heterogeneous morphology with porous of size between 2 μm − 10 μm that are distributed across the surface is identified. In addition to this, droplets produced by the electric arc discharge[17] are also deposited upon the surface with diametersbetween 2 μm and 15 μm. This effect is likely due to the enrichment of more noble species upon the surface achieved by the implantation process. ...
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To improve the corrosion resistance of different industrials application, we studied vanadium nitride (VN) and hafnium nitride (HfN) single layer thin film, which were deposited onto Si (100) and AISI 4140 steel substrates via r.f. magnetron sputtering technique in Ar/N2 atmosphere with purity at 99.99% for both V and Hf metallic targets. Both films were approximately 1.2 ± 0.1 μm thick. The crystallography structures that were evaluated via X-ray diffraction analysis (XRD) showed preferential orientations in the Bragg planes VN (200) and HfN (111). The chemical compositions for both films were characterized by EDX. Atomic Force Microscopy (AFM) was used to study the morphology; the results reveal grain sizes of 78 ± 2 nm for VN and 58 ± 2 nm for HfN and roughness values of 4.2 ± 0.1 nm for VN and 1.5 ± 0.1 nm for HfN films. The electrochemical performance in VN and HfN films deposited onto steel 4140 were studied by Tafel polarization curves and impedance spectroscopy methods (EIS) under contact with sodium chloride at 3.5 wt.% solution, therefore, it was found that the corrosion rate decreased about 95% in VN and 99% for HfN films in relation to uncoated 4140 steel, thus demonstrating, the protecting effect of VN and HfN films under a corrosive environment.
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The native passive film on the new Ti–15Ta–5Zr alloy surface contains the protective TiO2, Ta2O5 and ZrO2 oxides (XPS analysis). The decrease of the corrosion current densities and the increase of the polarisation resistances values signify the thickening of the passive film in time. The duplex oxide film formed by the inner, compact, layer and by the outer, porous layer was modelled; electrical parameters indicated the thickening over time both of the barrier and porous layers. XPS and SEM analyses demonstrated the in time deposition of new layers consisting by brushite in acid Ringer solution and from hydroxyapatite in neutral and alkaline Ringer solutions.