Abstract
In this paper we studied the influence of pre-treating the surface of 100Cr6 steel by ion beam nitriding at low temperature (380°C) on the surface topography and wear resistance of thin TiN coatings deposited by reactive ion beam assisted deposition. The specimens were characterized by grazing incidence X-ray diffraction, scanning electron microscopy and atomic force microscopy. The wear resistance of the TiN-coated specimens was evaluated by means of ball on disc tests. The results showed that application of a preliminary ion beam nitriding treatment slightly increased the surface roughness but improved the wear resistance of the 100Cr6 steel due to the formation of a diffusion zone containing the γ'-Fe4N nitride combined with the TiN coating.
ion beam nitriding; TiN; IBAD; wear; steel
1 Introduction
Nitriding processes comprise a series of thermo-chemical surface treatments which are
largely applied in industry with the objective of improving performance of steel
parts by diffusion of N into the steel surface. Surface hardness, corrosion
resistance, fatigue resistance and wear resistance are properties which can be
substantially improved by nitriding11. Menthe E, Rie KT, Schultze JW and Simson S. Structure and
properties of plasma nitrided stainless steel. Surface and Coatings Technology.
1995; 74-75:412-416.
http://dx.doi.org/10.1016/0257-8972(95)08246-8.
http://dx.doi.org/10.1016/0257-8972(95)0...
2. Lei MK and Zhang ZL. Microstructure and corrosion resistance of
plasma source ion nitrided austenitic stainless steel. Journal of Vacuum Science
& Technology A. 1997; 15(2):421-427.
http://dx.doi.org/10.1116/1.580501.
http://dx.doi.org/10.1116/1.580501...
3. Renevier N, Collignon P, Michel H and Czerwiec T. Low temperature
nitriding of AISI 316L stainless steel and titanium in a low pressure arc
discharge. Surface and Coatings Technology. 1999; 111(2-3):128-133.
http://dx.doi.org/10.1016/S0257-8972(98)00722-1.
http://dx.doi.org/10.1016/S0257-8972(98)...
-44. Leite MV, Figueroa CA, Corujeira Gallo S, Rovani AC, Basso RLO,
Mei PR, et al. Wear mechanisms and microstructure of pulsed plasma nitrided AISI
H13 tool steel. Wear. 2010; 269(5-6):466-472.
http://dx.doi.org/10.1016/j.wear.2010.04.037.
http://dx.doi.org/10.1016/j.wear.2010.04...
. The introduction of N into steel can be accomplished
either by inserting the work piece into a high temperature N-rich environment
(either gas or liquid) or by plasma assisted bombardment of N ions (ion beam
nitriding). Among these, ion beam nitriding is of particular interest because it
allows for excellent parameter control and higher efficiency at low temperatures
(300-450 °C) resulting in a more chemically uniform surface layer55. Zagonel LF, Bettini J, Basso RLO, Paredez P, Pinto H, Lepienski
CM, et al. Nanosized precipitates in H13 tool steel low temperature plasma
nitriding. Surface and Coatings Technology. 2012; 207:72-78.
http://dx.doi.org/10.1016/j.surfcoat.2012.05.081.
http://dx.doi.org/10.1016/j.surfcoat.201...
. The typical plasma nitrided
steel surface consists of an outermost thin iron nitride layer (commonly referred to
as “white layer”) followed by a relatively thicker N-rich diffusion zone close to
the steel substrate66. Sun Y and Bell T. Plasma surface engineering of low alloy steel.
Materials Science and Engineering A. 1991; 140(7):419-434.
http://dx.doi.org/10.1016/0921-5093(91)90458-Y.
http://dx.doi.org/10.1016/0921-5093(91)9...
. The
formation of the white layer can be suppressed in plasma nitriding by tuning process
parameters77. Kamminga JD, Hoy H, Janssen GCAM, Lugscheider E and Maes M. First
results on duplex coatings without intermediate mechanical treatment. Surface
and Coatings Technology. 2003; 174-175:671-676.
http://dx.doi.org/10.1016/S0257-8972(03)00578-4.
http://dx.doi.org/10.1016/S0257-8972(03)...
. Depending on its
chemical affinity with elements present in the steel substrate and on the nitriding
process parameters, N may remain in solution or give rise to a number of other
nitride compounds. The main phases present in the nitrided zone on steel surfaces
are ε-Fe2-3N and γ′-Fe4N nitrides, which exhibit very high
hardness (around 70HRC) and good corrosion resistance, thus improving the
mechanical, chemical and tribology properties of the constructional parts88. Ochoa EA, Figueroa CA and Alvarez F. Nitriding of AISI 4140 steel
by a low energy broad ion source. Journal of Vacuum Science & Technology A.
2006; 24(6):2113-2116. http://dx.doi.org/10.1116/1.2356480.
http://dx.doi.org/10.1116/1.2356480...
9. Walkowicz J, Smolik J and Miernik K. Research on physico-chemical
bases of the ion nitriding process control with the use plasma spectroscopic
diagnostics. Vacuum. 2000; 56(1):63-69.
http://dx.doi.org/10.1016/S0042-207X(99)00167-0.
http://dx.doi.org/10.1016/S0042-207X(99)...
-1010. Tillman W, Vogli E and Momeni S. Mechanical and tribological
properties of Ti/TiAlN duplex coatings on high and low alloy tool steels.
Vacuum. 2010; 8(3):387-392..
Physical Vapor Deposition (PVD) techniques are also commonly applied for enhancing
surface properties of steels. PVD coatings include TiN, TiC, TiCN and TiAlN, which
have a high hardness, low friction coefficient and high wear resistance. Since PVD
coatings are very thin, any applied loads which cause the surface and sub-surface to
deform must also be sustained by the steel base material: if the substrate undergoes
extensive plastic deformation the coating might collapse and fail prematurely1111. Dong H, Sun Y and Bell T. Enhanced corrosion resistance of
duplex coatings. Surface and Coatings Technology. 1997; 90(1-2):91-101.
http://dx.doi.org/10.1016/S0257-8972(96)03099-X.
http://dx.doi.org/10.1016/S0257-8972(96)...
. Hence, duplex coatings have
been developed whereby a preliminary nitriding treatment is applied followed by a
hard coating deposition. By combining these two processes a composite layer is
formed with the thin ceramic coating supported by the N-strengthened substrate,
which leads to superior fatigue and wear resistance66. Sun Y and Bell T. Plasma surface engineering of low alloy steel.
Materials Science and Engineering A. 1991; 140(7):419-434.
http://dx.doi.org/10.1016/0921-5093(91)90458-Y.
http://dx.doi.org/10.1016/0921-5093(91)9...
,1212. Garcia J and Pitonak R. The role of cemented carbide
functionally graded outer-layers on the wear performance of coated cutting
tools. International Journal of Refractory Metals & Hard Materials. 2013;
36:52-59. http://dx.doi.org/10.1016/j.ijrmhm.2011.12.007.
http://dx.doi.org/10.1016/j.ijrmhm.2011....
. The effectiveness of a duplex coating can be hampered
by insufficient adhesion between the hard coating and the nitrided steel and by
softening of the substrate due elevated temperatures during PVD. According to
Kamminga77. Kamminga JD, Hoy H, Janssen GCAM, Lugscheider E and Maes M. First
results on duplex coatings without intermediate mechanical treatment. Surface
and Coatings Technology. 2003; 174-175:671-676.
http://dx.doi.org/10.1016/S0257-8972(03)00578-4.
http://dx.doi.org/10.1016/S0257-8972(03)...
,1313. Kamminga JD, Doerwald D, Schreurs M and Janssen GCAM. Industrial
feasibility of the nitrocoat process. Surface and Coatings Technology. 2005;
200(5-6):1837-1841.
http://dx.doi.org/10.1016/j.surfcoat.2005.08.008.
http://dx.doi.org/10.1016/j.surfcoat.200...
, bad adhesion may be caused by
porosity in the nitride layer or by its decomposition during application of high
temperature PVD processes leaving a relatively softened α-Fe layer behind. The
presence of an iron nitride layer may also impair adhesion of the PVD coating and
improvements in performance have been observed by conducting the deposition process
after removal of the nitrided white layer1414. Panjan P, Čekada M, Kirn R and Soković M. Improvement of
die-casting tools with duplex treatment. Surface and Coatings Technology. 2004;
180-181:561-565.
http://dx.doi.org/10.1016/j.surfcoat.2003.10.119.
http://dx.doi.org/10.1016/j.surfcoat.200...
.
The application of PVD at low temperatures is difficult because of reduced ad-atom
mobility, which decreases coating density leading to inferior mechanical
performance1515. Patsalas P, Charitidis C and Logothetidis S. The effect of
substrate temperature and biasing on the mechanical properties and structure of
sputtered titanium nitride thin films. Surface and Coatings Technology. 2000;
125(1-3):335-340.
http://dx.doi.org/10.1016/S0257-8972(99)00606-4.
http://dx.doi.org/10.1016/S0257-8972(99)...
. In the Ion
Beam Assisted Deposition (IBAD) process, PVD is combined with ion bombardment. The
additional energy of the ion bombardment allows deposition of ceramic coatings at
lower temperatures, thus avoiding some of the difficulties involved in the
application of high temperature PVD on nitrided substrates1616. Škorié B and Kakaš D. Tribological Behavior of TiN and TiAlN
Deposited on Substrates Plasma Nitrided at Low Pressure. Materials and
Manufacturing Processes. 1995; 10(2):321-326.
http://dx.doi.org/10.1080/10426919508935025.
http://dx.doi.org/10.1080/10426919508935...
17. Škorić B, Kakaš D and Gredić T. Influence of plasma nitriding on
mechanical and tribological properties of steel with subsequent PVD surface
treatments. Thin Solid Films. 1998; 317(1-2):486-489.
http://dx.doi.org/10.1016/S0040-6090(97)00565-8.
http://dx.doi.org/10.1016/S0040-6090(97)...
-1818. Kakas D, Terek P, Kovacevic L, Miletic A and Skoric B. Influence
of interfacial layer thickness and substrate roughness on adhesion of TiN
coatings deposited at low temperatures by IBAD. Surface Review and Letters.
2011; 18(03n04):83-90.
http://dx.doi.org/10.1142/S0218625X11014497.
http://dx.doi.org/10.1142/S0218625X11014...
. Indeed, by comparing the IBAD and PVD processes
applied to previously quenched and tempered steel substrates, Škorić and co-workers
showed that IBAD led to improved properties due to densification of the hard
coating1919. Škorić B, Kakaš D, Rakita M, Bibić N and Peruškob D. Structure,
hardness and adhesion of thin coatings deposited by PVD, IBAD on nitrided
steels. Vaccum. 2004; 76(2-3):169-172.
http://dx.doi.org/10.1016/j.vacuum.2004.07.005.
http://dx.doi.org/10.1016/j.vacuum.2004....
. The IBAD process
can thus be used to produce dense and hard coatings with strong adhesion and also
allows for the independent control of several parameters e.g. ion bombardment
energy, ion to atom arrival ratio, ion current density and ion angle of incidence,
which influence the properties of the growing films1818. Kakas D, Terek P, Kovacevic L, Miletic A and Skoric B. Influence
of interfacial layer thickness and substrate roughness on adhesion of TiN
coatings deposited at low temperatures by IBAD. Surface Review and Letters.
2011; 18(03n04):83-90.
http://dx.doi.org/10.1142/S0218625X11014497.
http://dx.doi.org/10.1142/S0218625X11014...
.
In the present article, the influence of applying ion beam nitriding to a 100Cr6 bearing steel prior to the deposition of TiN films by IBAD was investigated. Wear resistance, microstructure and phase composition were investigated for IBAD TiN coatings applied both on previously nitrided surfaces and also on untreated surfaces.
2 Material and Methods
2.1 Substrate material
The substrate material prior to surface treatment was an annealed 100Cr6 bearing steel. Its nominal chemical composition is given Table 1. The steel specimens were used in the annealed state instead of the quenched and tempered condition, which is common for bearing steels. The reason for this was to avoid phase transformations during the nitriding treatment (carried out at 380°C), which could influence N diffusion throughout the process.
The specimens used for plasma nitriding and PVD coating were in the form of 20mm diameter discs with 2mm thickness which were all cut from the same rod. Prior to surface treatment, all samples were prepared by conventional grinding from 220 to 4000 SiC grid size, followed by polishing using 6.0, 3.0, 1.0 µm diamond paste and 0.25 µm colloidal silica suspension.
2.2 Ion beam nitriding and TiN deposition
TiN coatings were deposited on substrates with and without previous nitriding
treatments. Both processes (ion beam nitriding and film deposition) were
performed using an IBAD system, located at the Photovoltaic Conversion
Laboratory of the Physics Institute of the Campinas State University (Brazil).
This system consists mainly of a deposition chamber with two Kaufman ion sources
with 3 cm diameter, a support for four targets and a temperature controlled
(<1000 °C) sample holder. For more details regarding this system the reader
is referred to Hammer et al.2020. Hammer P, Victoria NM and Alvarez F. Electronic structure of
hydrogenated carbon nitride films. Journal of Vacuum Science & Technology A.
1998; 16(5):2941-2949. http://dx.doi.org/10.1116/1.581443.
http://dx.doi.org/10.1116/1.581443...
. The base pressure of the chamber was less than
10–4 Pa. Both processes, ion beam nitriding and TiN deposition,
were carried out independently following a sequence which began with sputter
cleaning using a 600 eV Ar+ beam for 5 minutes, followed by nitriding
(when applicable) and posterior TiN coating deposition. Identification of the
samples used in the present work is presented in Table 2.
Nitriding of the substrate was performed using a N+ beam of 0.2 keV and 19 mA that was directed to the substrate during 30 min. The temperature of the process was set to 380 °C and the working pressure was 1.5×10–2 Pa for all nitrided samples. Following the nitriding process, TiN films were deposited by IBAD by sputtering a Ti target with a 1.45 keV (80 mA) Ar ion beam in a N2 atmosphere. The N2 pressure was 5.5×10–2 Pa and the substrate temperature was set to 400 °C. The deposition time was 120 min for all samples. The hardness of the TiN coatings on both S and SN samples was measured with a CSEM Nanohardness tester using a diamond indenter and a load of 5N.
2.3 Microstructure and phase analyses
The microstructure of the 100Cr6 steel substrate and the TiN coatings was investigated after etching the samples with Nital 3% using by scanning electron microscopy (SEM) using a Philips XL-30 FEG microscope. In order to assess the phase constitution within the TiN coated samples, angle-dispersive X-ray Diffraction (XRD) experiments were carried out. The measurements were performed at the experimental station XPD of the Brazilian Synchrotron Radiation Laboratory (LNLS) at Campinas (Brazil). The radiation energy was set to 10.5 keV (λ = 1.1823 Å). The beam size was 4 mm × 1 mm. Diffractograms were obtained under a grazing incidence angle (ω) of 1°, which corresponds to an average penetration depth τ of 500 nm.
2.4 Topography and wear
The influence of the nitriding pre-treatment on surface topography of the coated samples was evaluated by Atomic Force Microscopy (AFM) in contact mode. The analyses were conducted in a CSM instruments Nano-Scratch Tester (NST). The wear resistance of each sample was studied by applying ball on disc tests. For these experiments, a 3.0 mm radius cemented carbide (WC-Co) sphere was used with a 5 N load over a total distance of 1000 m.
3 Results and Discussion
3.1 Microstructure and phase analyses
The surface hardness of the as-received and nitrided 100Cr6 substrates were, respectively, 2.6 ± 0.2GPa and 3.5 ± 0.2GPa. After TiN deposition, the surface hardness increased and the values obtained for both S and SN samples were between 22 and 26 GPa. Determination of the hardness values for the TiN coatings was difficult because of their reduced thickness, which required the use of a small applied test load (5 N). Because of this, the measurements were very sensitive to variations in surface roughness, hence the large variance in experimental values (22 to 26 GPa).
A cross-section SEM micrograph of the SN(TiN) sample is presented in Figure 1. The microstructure of the annealed hypereutectoid steel consists of a ferritic matrix with dispersed spheroidized cementite particles. It can also be observed that the average thickness of the TiN coatings deposited by IBAD amounts to about 400nm, and the coatings present a columnar grain structure. The TiN coating of the S(TiN) sample also exhibited a thickness of approximately 400 nm (not shown). From the micrograph presented in Figure 1, it is not possible to state whether the ion beam nitriding process conducted at 380 °C led to the formation of a white compound layer, but no indication on the formation of such layer was found (adhesion of the TiN coating, wear performance). The application of higher resolution microscopy techniques would be necessary to clarify the issue.
The results from phase analysis conducted by XRD on the S(TiN) and SN(TiN) samples are presented in Figures 2a and 2b, respectively. The differences with respect to the phase composition in both samples become clear by analyzing the XRD patterns. For the S(TiN) sample, phase analysis reveals the presence of ferrite and Fe3C that stem from the 100Cr6 substrate and TiN from the coating. In the SN(TiN) sample, which was nitrided prior to TiN deposition, it was possible to identify the presence of iron-rich γ’-Fe4N by the reflections of the (111), (200), (220) and (311) planes, as indicated in Figure 2b. In both Figures 2a and 2b, the TiN reflections are well defined but exhibit broadening (e.g. in comparison to the Fe reflections from the substrate), indicating small crystallite size and possibly a nanostructured layer. In addition, it is possible to notice that for both S(TiN) and SN(TiN) samples, the stronger reflections correspond to the (200) planes. The relative intensity of the diffraction lines may indicate the presence of preferential orientations in the coating. The results presented in Figures 2a and 2b indicate, therefore, that the preliminary nitriding treatment did not influence texture of the TiN coatings deposited by IBAD.
Grazing incidence X-ray diffraction patterns obtained for (a) untreated S(TiN) and (b) nitrided SN(TiN) samples.
The development of preferential orientations in TiN coatings depends on a number
of factors, such as ad-atom mobility, stoichiometry and surface energy, which
are in turn influenced by deposition process parameters such as temperature, ion
energy, ion current density and angle of ion incidence2121. Ma C-H, Huang J-H and Chen H. Texture evolution of
transition-metal nitride thin films by ion beam assisted deposition. Thin Solid
Films. 2004; 446(2):184-193.
http://dx.doi.org/10.1016/j.tsf.2003.09.063.
http://dx.doi.org/10.1016/j.tsf.2003.09....
. Owing to its NaCl type crystal structure,
the crystallographic planes with highest atomic density in TiN belong to the
{001} family2222. Combadiere L and Machet J. Reactive magnetron sputtering
deposition of TiN films. I. Influence of substrate temperature on structure,
composition and morphology of the films. Surface and Coatings Technology. 1997;
88(1-3):17-27. http://dx.doi.org/10.1016/S0257-8972(96)02870-8.
http://dx.doi.org/10.1016/S0257-8972(96)...
. In the
present case, since the (200) planes exhibit the strongest diffraction peaks,
texture in the TiN films appears to be controlled by the lower surface energy of
the dense {001} type planes. These results are in agreement with previous
investigations of TiN coatings produced by IBAD1919. Škorić B, Kakaš D, Rakita M, Bibić N and Peruškob D. Structure,
hardness and adhesion of thin coatings deposited by PVD, IBAD on nitrided
steels. Vaccum. 2004; 76(2-3):169-172.
http://dx.doi.org/10.1016/j.vacuum.2004.07.005.
http://dx.doi.org/10.1016/j.vacuum.2004....
,2323. Škorić B, Kakaš D, Rakita M, Bibic N and Rakita M.
Microstructural studies of TiN coatings prepared by PVD and IBAD. Surface
Science. 2004; 566-568:40-44.
http://dx.doi.org/10.1016/j.susc.2004.06.060.
http://dx.doi.org/10.1016/j.susc.2004.06...
. A more detailed explanation on texture
development in TiN coatings is provided by Gall et al.2424. Gall D, Kodambaka S, Wall MA, Petrov I and Greene JE. Pathways
of atomistic processes on TiN(001) and (111) surfaces during film growth: an ab
initio study. Journal of Applied Physics. 2003; 93(11):9086-9094.
http://dx.doi.org/10.1063/1.1567797.
http://dx.doi.org/10.1063/1.1567797...
.
3.2 Topography and wear
Figure 3 displays the surface topography of the samples investigated obtained by AFM in the vicinity of the wear tracks after the ball on disc tests. The average surface roughness (Ra) of the samples were determined and the values obtained were 0.077±0.008 µm and 0.083±0.008 µm for the S(TiN) and SN(TiN) samples, respectively.
The S(TiN) sample exhibits the lowest level of surface roughness, compatible with
the surface finishing of metallographic polishing to which the substrates were
initially subjected. Ion beam nitriding leads to an increase in surface
roughness, which can be explained by a number of different mechanisms which
involve: volumetric expansion of the substrate lattice due to incorporation of N
in solid solution and formation of nitrides, sputtering of the surface due to
the impact of N ions during deposition, as well as redeposition of the sputtered
material2525. Mahboubi F and Abdolvahabi K. The effect of temperature on
plasma nitriding behaviour of DIN 1.6959 low alloy steel. Vaccum. 2006;
81(3):239-243. http://dx.doi.org/10.1016/j.vacuum.2006.03.010.
http://dx.doi.org/10.1016/j.vacuum.2006....
,2626. Akbari A, Mohammadzadeh R, Templier C and Riviere JP. Effect of
the initial microstructure on the plasma nitriding behavior of AISI M2 high
speed steel. Surface and Coatings Technology. 2010; 204(24):4114-4120.
http://dx.doi.org/10.1016/j.surfcoat.2010.05.042.
http://dx.doi.org/10.1016/j.surfcoat.201...
. As the tribological system investigated (cemented
carbide against TiN) involves materials of elevated hardness, the main wear
mechanism appears to be abrasive, thus leading to appreciable breakup of the
sharper coating asperities.
The average volume losses of each sample after the wear tests are compared in Figure 4. The SN(TiN) duplex layered sample exhibited superior wear resistance in comparison to the S(TiN) sample, as can also be noticed by the larger amount of detached material shown in Figure 3. It is likely that this is due to hardening of the substrate with formation of γ’-Fe4N caused by the ion beam nitriding process, since in both materials the TiN coatings exhibited similar hardness (22-26GPa, Table 2) and also because the thin TiN coatings were completely removed during the wear tests. Thus, on the S(TiN) specimen removal of the hard outer layer exposed a soft annealed substrate leading to higher wear rates compared to the SN(TiN) sample.
4 Conclusions
In the present work, TiN deposition was performed by IBAD on annealed and ion beam nitrided substrates of 100Cr6 steel. In both cases, the TiN films were approximately 400 nm thick. The application of the preliminary nitriding treatment was found to increase surface roughness slightly in comparison to TiN films deposited on non-nitrided 100Cr6 samples, and also led to the formation of γ’-Fe4N. It was possible to show that the duplex coating formed by nitriding and TiN deposition of 100Cr6 steel has superior wear resistance properties in comparison to plain TiN coatings deposited on non-treated substrates.
Acknowledgements
This work was supported by the NanoCom Network Project, 7th Framework Program – IRSES – Project Nr. 247524. SSV, FA and HP are CNPq fellows.
References
-
1Menthe E, Rie KT, Schultze JW and Simson S. Structure and properties of plasma nitrided stainless steel. Surface and Coatings Technology. 1995; 74-75:412-416. http://dx.doi.org/10.1016/0257-8972(95)08246-8.
» http://dx.doi.org/10.1016/0257-8972(95)08246-8 -
2Lei MK and Zhang ZL. Microstructure and corrosion resistance of plasma source ion nitrided austenitic stainless steel. Journal of Vacuum Science & Technology A. 1997; 15(2):421-427. http://dx.doi.org/10.1116/1.580501.
» http://dx.doi.org/10.1116/1.580501 -
3Renevier N, Collignon P, Michel H and Czerwiec T. Low temperature nitriding of AISI 316L stainless steel and titanium in a low pressure arc discharge. Surface and Coatings Technology. 1999; 111(2-3):128-133. http://dx.doi.org/10.1016/S0257-8972(98)00722-1.
» http://dx.doi.org/10.1016/S0257-8972(98)00722-1 -
4Leite MV, Figueroa CA, Corujeira Gallo S, Rovani AC, Basso RLO, Mei PR, et al. Wear mechanisms and microstructure of pulsed plasma nitrided AISI H13 tool steel. Wear. 2010; 269(5-6):466-472. http://dx.doi.org/10.1016/j.wear.2010.04.037.
» http://dx.doi.org/10.1016/j.wear.2010.04.037 -
5Zagonel LF, Bettini J, Basso RLO, Paredez P, Pinto H, Lepienski CM, et al. Nanosized precipitates in H13 tool steel low temperature plasma nitriding. Surface and Coatings Technology. 2012; 207:72-78. http://dx.doi.org/10.1016/j.surfcoat.2012.05.081.
» http://dx.doi.org/10.1016/j.surfcoat.2012.05.081 -
6Sun Y and Bell T. Plasma surface engineering of low alloy steel. Materials Science and Engineering A. 1991; 140(7):419-434. http://dx.doi.org/10.1016/0921-5093(91)90458-Y.
» http://dx.doi.org/10.1016/0921-5093(91)90458-Y -
7Kamminga JD, Hoy H, Janssen GCAM, Lugscheider E and Maes M. First results on duplex coatings without intermediate mechanical treatment. Surface and Coatings Technology. 2003; 174-175:671-676. http://dx.doi.org/10.1016/S0257-8972(03)00578-4.
» http://dx.doi.org/10.1016/S0257-8972(03)00578-4 -
8Ochoa EA, Figueroa CA and Alvarez F. Nitriding of AISI 4140 steel by a low energy broad ion source. Journal of Vacuum Science & Technology A. 2006; 24(6):2113-2116. http://dx.doi.org/10.1116/1.2356480.
» http://dx.doi.org/10.1116/1.2356480 -
9Walkowicz J, Smolik J and Miernik K. Research on physico-chemical bases of the ion nitriding process control with the use plasma spectroscopic diagnostics. Vacuum. 2000; 56(1):63-69. http://dx.doi.org/10.1016/S0042-207X(99)00167-0.
» http://dx.doi.org/10.1016/S0042-207X(99)00167-0 -
10Tillman W, Vogli E and Momeni S. Mechanical and tribological properties of Ti/TiAlN duplex coatings on high and low alloy tool steels. Vacuum. 2010; 8(3):387-392.
-
11Dong H, Sun Y and Bell T. Enhanced corrosion resistance of duplex coatings. Surface and Coatings Technology. 1997; 90(1-2):91-101. http://dx.doi.org/10.1016/S0257-8972(96)03099-X.
» http://dx.doi.org/10.1016/S0257-8972(96)03099-X -
12Garcia J and Pitonak R. The role of cemented carbide functionally graded outer-layers on the wear performance of coated cutting tools. International Journal of Refractory Metals & Hard Materials. 2013; 36:52-59. http://dx.doi.org/10.1016/j.ijrmhm.2011.12.007.
» http://dx.doi.org/10.1016/j.ijrmhm.2011.12.007 -
13Kamminga JD, Doerwald D, Schreurs M and Janssen GCAM. Industrial feasibility of the nitrocoat process. Surface and Coatings Technology. 2005; 200(5-6):1837-1841. http://dx.doi.org/10.1016/j.surfcoat.2005.08.008.
» http://dx.doi.org/10.1016/j.surfcoat.2005.08.008 -
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» http://dx.doi.org/10.1016/j.surfcoat.2003.10.119 -
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Publication Dates
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Publication in this collection
Jan-Feb 2015
History
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Received
24 Jan 2014 -
Reviewed
10 Dec 2014