Journal of Biomaterials and Nanobiotechnology, 2013, 4, 374-384
http://dx.doi.org/10.4236/jbnb.2013.44047 Published Online October 2013 (http://www.scirp.org/journal/jbnb)
Friction and Wear Behavior of Ti-6Al-7Nb Biomaterial
Alloy
Mamoun Fellah1*, Omar Assala1, Mohamed Labaïz1, Leila Dekhil2, Alain Iost3
1Surface Engineering and Tribology Team, Laboratory of Metallurgy and Engineering Materials, BADJI Mokhtar-Annaba University,
Annaba, Algeria; 2Laboratory of Formability and Metallic Materials, BADJI Mokhtar-Annaba University, Annaba, Algeria; 3La-
boratory of Metallurgy, ARTS ET METIERS ParisTech, Lille, France.
Received 28 January 2013; revised 1 March 2013; accepted 1 April 2013
Copyright © 2013 Mamoun Fellah et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
Titanium has been increasingly applied to biomedical application because of its improved mechanical characteristics,
corrosion resistance and biocompatibility. However their application remains limited, due to the low strength and poor
wear resistance of unalloyed titanium. The purpose of this study is to evaluate the friction and wear behavior of
high-strength titanium alloys: Ti-6Al-7Nb used in femoral stem (total hip prosthesis). The oscillating friction and wear
tests have been carried out in ambient air with oscillating tribotester in accord with standards ISO 7148, ASTM
G99-95a, ASTM G 133-95 under different conditions of normal applied load (3, 6 and 10 N) and sliding speed (1, 15
and 25 mm·s−1), and as a counter pair we used the ball of 100C 6, 10 mm of diameter. The surface morphology of the
titanium alloys has been characterized by SEM, EDAX, micro hardness, roughness analysis measurements. The behav-
ior observed for both samples suggests that the wear and friction mechanism during the test is the same for Ti alloys,
and to increase resistance to wear and friction of biomedical titanium alloys used in total hip prosthesis (femoral stems)
the surface coating and treatment are required.
Keywords: Tribological Behavior; Friction and Wear Tests; Biomaterial; Total Hip Prosthesis; Ti-6Al-7Nb
1. Introduction
Titanium and its alloys have been used as implant mate-
rials due to their very good mechanical and corrosion re-
sistance and biocompatibility [1-7]. The most used bio-
materials were commercially pure titanium (CP-Ti) which
is used in clinics [8,9], although CP-Ti has been pointed
out to have disadvantages of low strength, difficulty in
polishing, and poor wear resistance [10]. Therefore, Tita-
nium is still insufficient for high-stress applications; e.g.,
long spanned fixed prostheses and the frameworks of
removable partial dentures [11,12].
Ti-6Al-4V alloy, originally developed as an aeronau-
tical material, has been tested as a replacement for CP-Ti,
because of its high mechanical properties with sufficient
corrosion resistance [13-17]; however, the cytoxicity of
elemental Vanadium is questionable [18-20]. Subse-
quently, some researches prove that Vanadium and Alu-
minum ions released from this ternary alloy can induce
cytotoxic effects or neurological disorders, respectively
[21,22]. Also, for long-term, this alloy has transferred in
sufficient load to adjacent bones, resulting in bone re-
sorption and eventual loosening of the implant [23,24].
Another ternary alloy used as implants was Vanadium
free, α + β alloy, especially Ti-6Al-7Nb alloy [25-27]
that revealed improved mechanical characteristics, corro-
sion resistance and biocompatibility. Developed for or-
thopedics application as a wrought material, it has been
evaluated as a new alloy for total hip prostheses. Nio-
bium exhibits a similar effect to Vanadium in stabilizing
β phase in the Ti-Nb binary system, which is necessary
for providing the α, β two-phase structure. Therefore,
Niobium was used as the ternary element to produce the
desirable microstructure in the Ti-6Al-7Nb alloy [28].
As compared with Ti-6Al-4V alloy, in a tensile test,
these alloys show slightly lower strength and about 40%
higher elongation. In addition, after long term immersion
in 1.0% lactic acid, the amount of Titanium ion released
from Ti-6Al-7Nb alloy was less than that from Ti-6Al-
4V alloy and comparable to that from titanium [29].
Ti-6Al-7Nb alloy showed castability slightly lower than
*Corresponding author.

Friction and Wear Behavior of Ti-6Al-7Nb Biomaterial Alloy 375
that of CP-Ti, but less casting porosity, which is advan-
tageous in terms of reliability of castings [29].
Although Ti-6Al-7Nb alloy castings have been inves-
tigated for orthopedics application from several aspects
such as mechanical properties, corrosion resistance and
castability, no studies have reported on friction and wear
resistance, which is an important factor for a material for
total hip prostheses. In this study, friction and wear
characteristics of Ti-6Al-7Nb alloys were evaluated by a
ball on disc tribometre in accord with standards ISO
7148, ASTM G99-95a, ASTM G 133-95.
2. Materials and Methods
2.1. Materials
The materials used in this study are the Ti-6Al-7Nb as a
total hip prosthesis (femoral stem) and Ti-6Al-4V that
was cuted from a titanium cylindrical bar correspond to
ISO 5832-3 part 3/01-07-199 (was supplied by ENSAM
Lille, France). The composition of titanium alloys used
in this study is specified in Table 1. It is known that the
fixation of the implant is greatly dependent on good me-
chanical interlocking between the rough surface of the
implant and tissue [30]. So, the surfaces of the alloys
were abraded with 600 abrasive papers firstly and pol-
ished with colloidal silica, all the samples were cleaned
in an ultrasonic bath with acetone, ethanol, and distilled
water, respectively, for 10 min and then dried in hot air
and saved in the desiccators for use in different charac-
terizations.
2.2. Tribological Study
Pin on disc, ball on disc and sphere on plan tribological
tests (Figures 1 and 2) were carried out using the fol-
lowing prosthetic materials: Ti-6Al-4V and Ti-6Al-7Nb
alloys, against 100C6 and abrasive paper number 320
(Sic).
2.2.1. Plan Contact
The contact pair, which studies the tribological pair, is, in
this case, the sample Ti-6Al-7Nb and sandpaper (320
abrasive papers). The parameters taken into account for
this test are the applied load and the rotational speed. The
test time is kept constant, and the weight loss is the
difference in weight of the sample weighed before and
after the test with a microelectronic balance whose accu-
racy is of the order 10−3 g. The samples were cleaned
with acetone before each weight; the surface roughness
of the test sample is measured before and after the test.
2.2.2. Friction Behavior
In this work, friction and wear tests have been carried out,
in ambient air with oscillating tribometer in accord with
standards ISO 7148, ASTM G99-95a, ASTM G 133-95
Figure 1. Scheme of the contact geometry (plan contact): 1:
speed regulator, 2: support, 3: rotating tray, 4: load applied,
5: sample, 6: retaining frame. Friction pair used: Ti-6Al-
7Nb sliding against number 320 abrasive paper. Sliding dis-
tance: 1400 m.
Figure 2. (a) Photography and (b) Scheme of the contact
geometry (alternative movement) and Tribotester System: 1:
table, carry sample on alternative movement (wear track
radius = 10 mm), 2: a sensor to measure heat and humidity,
3: ball 100C6 steel, 4: load applied FN, 5: Sample.
(Figure 2), under different condition of normal load (3, 6
and 10 N) and sliding speed (1, 15 and 25 mm·s−1), as a
counter pair we used the 100C6 ball, 10 mm in diameter
as presented in Table 2.
3. Results and Discussion
3.1. Surface and Microstructural Analysis
Microstructure
1) An acidic etchant (3 ml HF, 6 ml HNO3 and 100 ml
H2O for 10 s to reduce the influence of surface harden-
ing.
2) The samples are mechanically polished and chemi-
cally etched with a solution of 3 ml HF, 6 ml HNO3 and
100 ml H2O for 10 s to reduce the influence of surface
hardening, the microstructure was studied using optical
microscopy (Leica DMLM).
3) The microstructure of Titanium alloy was shown in
Figure 3 respectively, the photography consisted of glo-

Friction and Wear Behavior of Ti-6Al-7Nb Biomaterial Alloy 376
Table 1. Chemical composition (wt%) of Ti-6Al-7Nb.
Element Al Nb V Fe Mo O Si C Ta N Ti
% 6.2 7.4 - 0.10 0.005 0.0001 0.0002 0.0015 0.46 - Balance
Table 2. Work condition of the alternative movement wear
test oscillating tribotester.
Friction pairs used 1) Ball 1006C/Ti6Al4V,
2) Ball 1006C/Ti6Al7Nb
Sliding speed 1, 15 and 25 mm·s−1
Normal load 3, 6 and 10 N
Wear track radius 10 mm
100C6 ball diameter 10 mm
Temperature 25˚C
Humidity 38%
Figure 4. EDAX microanalysis of Ti-6Al-7Nb alloy.
The roughness (Figure 8) of the samples in 3D was
studied using Surface Data Veeco: Mag 5.0 X, Mode
VSI.
Roughness Analysis
The studied substrates are of biomedical interest. They
must therefore meet the standards imposed by the field of
biomedicine particularly at the surface of the material
deposited on the auricular surfaces of hip prostheses in
which Ti-6Al-4V and Ti-6Al-7Nb are the hip implant.
The roughness of the samples was obtained (Table 3 and
Figures 8(a)-(c)), meets the standards of biomedicine,
namely, roughness for metal parts as specified in ISO
7206-2:1996 [32]. The roughness values samples were
5.03 and 0.01 µm for Ti-6Al-7Nb before and after
polishing respectively and 0.06 µm for Ti-6Al-4V after
polishing.
Figure 3. Optical micrographs showing the microstructure
of Ti-6Al-7Nb alloy etched with a solution of 3 ml HF, 6 ml
HNO3 and 100 ml H2O for 10 s the figure consisted of glo-
bular and acicular α grains (white grains) within a matrix
containing equiaxial grains β (dark grains).
bular and acicular α grains (white grains) within a matrix
containing equiaxial grains β (dark grains). The acicular
shape of the α phase is present in the Figure 3 in an ar-
rangement known as basket-weave which characterizes
the Widmanstätten structure. 3.2. Tribological Study
4) The chemical composition presented in Table 1 was
acquired using spectrometer (Spectrolab) and energy-
dispersive spectroscopy (EDS, PHILIPS XL 30 ESEM-
FEG, and EDX IMIX-PTS.
3.2.1. Plan Contact
The weight loss (Figure 9) of titanium samples, tested at
3.5 N loads, is approximately proportional to the number
of revolutions. Nevertheless, the wear was systematically
greater to Ti-6Al-7Nb as expected. The behavior ob-
served for both samples suggests that the wear mecha-
nism during the test is the same (abrasive wear). In the
case of Ti-6Al-4V samples, its weight loss was ~85% of
the one observed for the Ti-6Al-7Nb samples. According
to the Archard’s law, the volumetric loss of the material
is inversely proportional to the hardness value of the
material [33]. This implies that the higher the hardness of
the material, the smaller is the volume loss. The present
alloys exhibit significant difference in hardness values,
so that the experimental sliding wear data correlate well
5) The titanium samples were examined using energy
dispersive X-Ray (EDX) analysis. The spectra for the
overall analysis are shown in Figures 4 and 5. The EDX
spectrum shows different peaks that correspond to the
different elements contained in the substrate. In the case
of Ti-6Al-7Nb, the Ti peak is more pronounced than that
of aluminum (Al), Niobium (Nb), iron (Fe), Molybde-
num (Mo) and tantalum (Ta) are also present. The che-
mical compositions of the studied samples were in com-
pliance with that of a Ti-6Al-7 Nb. The instrumented
microharndnesse (Figures 6 and 7), was studied using
ZWICK 2.5.

Friction and Wear Behavior of Ti-6Al-7Nb Biomaterial Alloy 377
Figure 5. XRD patterns of Ti-6Al-7Nb alloy.
Figure 6. Example of micro-hardness P-h curve [31].
with Archard’s law.
3.2.2. Friction Coefficient
It is instead to know the wear and friction coefficient of
ball 100C6 steel (Figure 10), before studying the coeffi-
cient of friction of samples.
The evolution curves of friction coefficient of Ti6A7Nb
versus sliding distance (number of cycles) Table 4 and
Figures 11-18 are almost the same form wholes in terms
of load and speed. The analysis of these curves to dis-
tinguish several periods, or successive regimes of friction
and wear:
1) The first period, during which the friction coeffi-
cient increases rapidly, an accommodation, is the surface
of the first body the most ductile [34], in this case the
steel. The relief is so attenuated; the roughness of the
surface of the steel is reduced by plastic deformation
2) The second period is characterized by a slight de-
crease in the friction coefficient. Probably, the third body
on the track generated by frictional wear of the steel
plays a role comparable to that of a solid lubricant.
3) The third period is defined by a significant increase
in the friction coefficient. The third body is fragmented
010 20 30
0
10
20
30
40
50
Force standar d e n N
Empreinte
(a)
010 20 30
0
10
20
30
40
50
Force standard en N
Empreinte
(b)
Figure 7. P–h curves during micro hardness experiments
with loading speed (0.2 mm·min−1), under a maximum load
(50 N) of: (a) Ti-6Al-4V; (b) Ti-6Al-7Nb.
and oxidizes very probably plays a role abrasive, then the
virtual stabilization of the friction coefficient.
4) The fourth and final period is near stabilization of
the friction coefficient.
The friction test results of Ti-6Al-7Nb and Ti-6Al-4V,
are illustrated in Table 4 and Figures 11-18 respectively.

Friction and Wear Behavior of Ti-6Al-7Nb Biomaterial Alloy 378
Figure 8. The optical 3D photo of Ti alloys, (a) Ti-6Al-7Nb
before polishing as received as femoral stem; (b) Ti-6Al-
7Nb after polishing; (c) Ti-6Al-4V after polishing.
Table 3. Surfaces statistics of Ti alloys as received (stem
femoral) and after polishing.
Ti-6Al-7N as
received
Ti-6Al-7Nb after
preparation
Ti-6Al-4V after
preparation
Ra (µm) 5.03 0.01 0.06
Rq (µm) 7.42 0.02 0.08
Rz (µm) 45.20 0.57 1.0.5
Rt (µm) 40.43 0.54 1.19
Figure 9. Wear diagrams (weight loss (g·cm−3)) of Ti-6Al-
7Nb, Ti-6Al-4V and ceramic sliding against (abrasive paper
number 320).
Figure 10. Wear marks of 100C6 steel ball under the fol-
lowing conditions: time = 1 h, FN = 10 N, sliding speed 8
mm/s with a same oscillating tribotester [31].
It is seen from Figure 11 that, the friction coefficient
showed a lower value (approx. 0.248) up to 20 cycles
and then it increased to the average 0.4 value between 40
and 1000 distance (cycles). The reason might be due to
an oxide layer formed on Ti-6Al-7Nb and, therefore, the
coefficient of friction showed the lower value until 20 m.
However, that oxide layer was torn and then 1006C ball
was completely touched on the substrate and, therefore,
the friction coefficient was obtained at a higher value
(0.538). In Figure 12, it is seen that the friction coeffi-
cient curves of Ti-6Al-7Nb, are the same form for all test
conditions sliding speed and normal load applied, the
average friction coefficient was obtained as 0.54 at
sliding speed 25 mm·s−1 under 10 N, It is also obvious in
Figure 12, that the coefficient of friction displayed a
lower value of 0.129 up to 20 cycle at sliding speed 1
mm·s−1, under 3 N of normal load and then it sharply.
Increased to the average value of 0.518 (Table 4) for
the same conditions 1 mm·s−1.
1) Influence of the Load Applied to the Friction
Coefficient
The influence of normal load applied on the evolution
of friction coefficient of Ti-6Al-7Nb and Ti-6Al-4V
under different condition of loads (3, 6 and 10 N) at slid-
ing speeds (1, 15 and 25 mm·s−1), was represented in
Table 5 and Figures 13-15. It is seen in the Figure 13,
that the mean coefficient of friction at 1 mm·s−1 it

Friction and Wear Behavior of Ti-6Al-7Nb Biomaterial Alloy 379
Table 4. Values of friction coefficient of Ti-6Al-7Nb versus sliding distance (1, 15 and 25 mm·s−1) under different loads 3, 6
and 10 N.
Speed 1 mm·s−1 15 mm·s−1 25 mm·s−1
FN (N) Star
COF
Min
COF
Max
COF
Mean
COF
PH Ca
(Mpa)
Star
COF
Min
COF
Max
COF
Mean
COF
PH Ca
(Mpa)
Star
COF
Min
COf
Max
COF
Mean
COF
PHCa
(Mpa)
3 N 0.129 0.068 0.589 0.339 524 0.2480.2480.5380.4 531 0.3490.349 0.49 0.419 532
6 N 0.325 0.197 0.546 0.36 660 0.4050.3390.5080.413 670 0.3330.333 0.482 0.418 670
10 N 0.251 0.213 0.518 0.357 783 0.3970.3250.48 0.398 795 0.3670.344 0.54 0.407 795
PH Ca: Hertz pressure (calculated) (Mpa); Star COF: the start value of coefficient of friction; Min COF: the minimum value of coefficient of friction; Mean
COF: the mean value of coefficient of friction; Max COF: the maximum value of coefficient of friction; FN (N): a normal load applied (N).
Figure 13. Friction coefficient vs sliding distance for Ti al-
loys and ceramic under different conditions of load 3, 6 and
10 N at 1 mm·s−1 sliding speed.
Figure 11. Friction coefficient vs. sliding distance for Ti-
6Al-7Nb under 3 N applied load at 15 mm·s−1 sliding speed.
Figure 14. Friction coefficient vs sliding distance for Ti al-
loys and ceramic under different conditions of load 3, 6 and
10 N at 15 mm·s−1 sliding speed.
Figure 12. Friction coefficient vs. sliding distance for Ti-
6Al-7Nb under different conditions of load 3, 6 and 10 N at
tows sliding speed 15 and 25 mm·s−1.
reaches the mean value of 0.339, 0.36 and 0.357 of
Ti-6Al-7Nb under normal load 3, 6 and 10 N respec-
tively, also it seen in the some Figure 13, that the Ti-
6Al-4V almost has the same mean value of friction co-
efficient of Ti-6Al-7Nb.
The Figures 14 and 15 are presented the evolution of
friction coefficient of Ti-6Al-7Nb and Ti-6Al-4V vs.
sliding distance under different conditions of load 3, 6
and 10 N at sliding speeds 1 and 25 mm·s−1 respectively,
it seen that the samples almost has the same mean value
of friction coefficient that’s increased to the average
values of (0.37 to 0.5). Figure 15. Friction coefficient vs sliding distance for Ti al-
loys and ceramic under different conditions of load 3, 6 and
10 N at 25 mm·s−1 sliding speed.
2) Influence of Speed

Friction and Wear Behavior of Ti-6Al-7Nb Biomaterial Alloy 380
Figure 16. friction coefficient vs sliding distance for Ti al-
loys and ceramic under different conditions of sliding speed
1, 15 and 25 mm·s−1 at normal load 3 N.
Figure 17. Friction coefficient vs sliding distance for Ti al-
loys and ceramic under different conditions of sliding speed
1, 15 and 25 mm·s−1 at normal load 6 N.
Figure 18. Friction coefficient vs sliding distance for Ti al-
loys and ceramic under different conditions of sliding speed
1, 15 and 25 mm·s−1 at normal load 10 N.
Figures 16-18, represented the influence of loads
applied to the evolution of friction coefficient of Ti-6Al-
7Nb, and Ti-6Al-4V under different condition sliding
speeds (1, 15 and 25 mm·s−1), at 3, 6 and 10 N load
applied respectively. It is seen that the mean coefficient
of friction of the samples displayed a lower value at 1
mm·s−1 sliding speed, and then it sharply increased to the
average value with increasing of sliding speed as show-
ing in the Table 5 and Figure 19.
3.2.3. Wear
In the wear test, the volumetric wear rate was calculated
by the help of mechanical profilometer as 57.62 × 10−3
mm3·N·mm−1 for the Ti-6Al-Nb. A 100C6 ball did the
grinding from the sample surface, that is, abrasive wear
occurred on the surface and this is illustrated in Figures
20 and 21. Volumetric wear was determined as 5.48 ×
10−3, 9.64 × 10−3 and 13.12 × 10−3 mm3·N·mm−1 at 1
mm·s−1 sliding speed under loads 3, 6 and 10 respectively.
Finally, the volumetric wear was a same for a both slid-
ing speed 15 and 25 between 20.67 × 10−3 mm3·N·mm−1
and 57.62 × 10−3 mm3·N·mm−1. Table 6 and Figure 19,
provides the wear volume of the investigated alloys as a
function of the sliding speed. The volumetric wear data
reveal that the volume loss, irrespective of alloy com-
position and microstructure, increases as the sliding
speed increases.
Friction versus wear: The strength of materials de-
pends on three groups of factors in friction conditions
[35]. Those factors are shown as follows:
1) Internal reasons determined material property;
2) Friction type (slipping, rolling) and working con-
ditions (relative movement speed, load, application type,
temperature); and
3) Working environment and lubricants.
4. Conclusions
Wear characteristics of high-strength titanium alloys
Ti-6Al-7Nb were evaluated in a wear test simulating the
friction for Total hip prosthesis application. The oscillat-
ing friction and wear resistance have been carried out in
ambient air with oscillating tribotester in accord with
standards ISO 7148, ASTM G99-95a and ASTM G133-
95. On the one hand, the friction and wear tests were
carried out to see the type of wear and to quantify the
weight loss; on the other hand, to see the variation in the
friction coefficient of the studied couples under different
conditions of load (3, 6 and 10 N) and sliding speed (1,
15 and 25 mm·s−1) as counter pairs, we used the ball of
100C6 steel, 10 mm in diameter. The following observa-
tions and conclusions were obtained:
1) The wear resistance of Ti-6Al-7NB alloy is sub-
stantially lower than that of the Ti-6Al-4V tested under
deferent conditions of load and sliding speed. The extent
of wear is smallest for Ti-6Al-4V with highest hardness.
2) The coefficient friction as shown in Figure 19, of
both alloys increases with increasing sliding speed. How-
ever, Ti-6Al-7Nb alloy shows no significant variation of
coefficient of friction with (15 and 25 mm·s−1) sliding
speeds, while the coefficient of Ti-6Al-4V increases
linearly with increasing sliding speed. This behavior is
attributed to the predominant wear mechanism.
3) The two Ti alloys had similar friction and wear per-
formance, although their grain structures and composi-

Friction and Wear Behavior of Ti-6Al-7Nb Biomaterial Alloy 381
Table 5. Mean value of coefficient of friction of Ti alloys and ceramic under different conditions of sliding speeds (1, 15 and
25 mm·s−1) and normal loads (3, 6 and 10 N).
Speed 1 mm·s−1 15 mm·s−1 25 mm·s−1
Fn (N) Ti-6Al-7Nb Ti-6Al-4V Ti-6Al-7Nb Ti-6Al-4V Ti-6Al-7Nb Ti-6Al-4V
3 (N) 0.339 0.356 0.4 0.497 0.419 0.489
6 (N) 0.36 0.297 0.413 0.473 0.418 0.565
10 (N) 0.357 0.374 0.398 0.452 0.407 0.476
Table 6. Volumetric wear rate of Ti-6Al-7Nb and Ti-6Al-4V
under different conditions of sliding speeds (1, 15 and 25
mm·s−1) and normal loads (3, 6 and10 N).
Volumetric wear mm3·N·mm−1
Sliding speed
mm/s Load (N) Ti-6Al-4V Ti-6Al-7Nb
3 4.45 × 10−3 5.48 × 10−3
6 8.24 × 10−3 9.64 × 10−3 1 mm·s−1
10 11.08 × 10−3 13.12 × 10−3
3 20.35 × 10−3 22.06 × 10−3
6 37.98 × 10−3 38.1 × 10−3 15 mm·s−1
10 51.55 × 10−3 57.35 × 10−3
3 27.32 × 10−3 31.38 × 10−3
6 42.15 × 10−3 45.28 × 10−3
25 mm·s−1
10 54.21 × 10−3 57.62 × 10−3
Figure 19. Mean coefficient of friction of Ti alloys and cera-
mic under different conditions of sliding speeds (1, 15 and
25 mm·s−1) and applied loads (3, 6 and 10 N).
Figure 20. The worn surfaces, severe deformation and plas-
tic flow of Ti-6Al-4V, sliding against ball 100C6 steel (r = 10
mm): (a) Wear marks under normal load 3, 6 and 10 N at
sliding speed 15 mm·s−1; (b) and (c) At normal load 6 N and
sliding speed 15 mm·s−1; (d) and (e) At normal load 10 N
and sliding speed 15 mm·s−1; (f) At normal load 10 N and slid-
ing speed 25 mm·s−1. Arrows indicate the sliding direction.
tions are different.
4) Large frictional fluctuations occurred, probably
caused by formation and periodic, localized fracture of a
transfer layer.
5) Higher friction coefficient with larger fluctuation
and higher wear rate were observed at the higher siding
speed.
plastic deformation and adhesive wear at elevated speed.
6) In all curves under deferent conditions, the friction
coefficient firstly decreases and then increases as a func-
tion of the sliding distance. The evolution of the friction
coefficient is related to composition of the worn surfaces.
8) The weight loss quantifying the wear of a soft body
slipping on a hard surface is proportional not only to the
distance from the slip but also with the normal load
applied.
7) The wear mechanism of Ti-6Al-4V transforms from
ploughing and peeling off wear at low sliding speed to
9) The sliding speed has a principal effect to act on the
temperature of the contact zone. Going beyond a critical

Friction and Wear Behavior of Ti-6Al-7Nb Biomaterial Alloy 382
Figure 21. The worn surfaces, severe deformation and plas-
tic flow of Ti-6Al-7Nb sliding against ball 1006C6 steel (r =
10 mm), under normal load 6 N at sliding speed 15 mm·s−1
((a), (b) and (c)), normal load 10 N at sliding speed 15
mm·s−1 ((d) and (e)), and normal load normal load 10 N at
sliding speed 25 mm·s−1 ((f) and (g)). Arrows indicate the
sliding direction.
speed involves the surface fusion of the most fusible
body.
10) The increase in the temperature of the contact with
the speed inducing structure transformations increases
the reactivity of surfaces with respect to the environment
(oxidation in the presence of air). Above a certain tem-
perature and thus for speeds of slip higher than a break-
ing value, the oxide film, resulting from a permanent
oxidation, is reconstituted with the fur as it is destroyed
by wear.
5. Acknowledgements
This work was realized in collaboration with the metal-
lurgical laboratory of ARTS ET METIERS ParisTech in
Lille, France. The authors wish to thank Prof. Alain Iost
the Director of Laboratory of Metallurgy, for kindly sup-
plying the Ti-6Al-4V metal bars and Ti-6Al-7Nb femoral
stem, and permitting facilities to use the SEM and tribo-
tester.
REFERENCES
[1] M. Niinomi, “Mechanical Biocompatibilities of Titanium
Alloys for Biomedical Application,” Journal of the Me-
chanical Behavior of Biomedical Materials, Vol. 1, No. 1,
2008, pp. 30-42.
http://dx.doi.org/10.1016/j.jmbbm.2007.07.001
[2] L. E. Murr, S. A. Quinones, S. M. Gaytan, M. I. Lopez, A.
Rodela, et al., “Microstructure and Mechanical Behaviour
of Ti-6Al-4V Produced by Rapid-Layer Manufacturing,
for Biomedical Applications,” Journal of the Mechanical
Behavior of Biomedical Materials, Vol. 2, No. 1, 2009,
pp. 20-32. http://dx.doi.org/10.1016/j.jmbbm.2008.05.004
[3] Z.-B. Caia, G.-A. Zhangb, Y.-K. Zhua, et al., “Torsional
Fretting Wear of a Biomedical Ti6Al7Nb Alloy for Ni-
trogen Ion Implantation in Bovine Serum,” Tribology In-
ternational, Vol. 59, 2013, pp. 312-320.
http://dx.doi.org/10.1016/j.triboint.2012.06.009
[4] N. Masahashi, Y. Mizukoshi, S. Semboshi, K. Ohmura, S.
Hanada, et al., “Photo-Induced Properties of Anodicox-
idelms on Ti6Al4V,” Journal of Thin Solid Films, Vol.
520, No. 15, 2012, pp. 4956-4964.
http://dx.doi.org/10.1016/j.tsf.2012.03.026
[5] M. Janecek, F. Nový, J. Stráský, P. Harcuba and L. Wag-
ner, “Fatigue Endurance of Ti-6Al-4V Alloy with Elec-
tro-Eroded Surface for Improved Bone In-Growth,” Jour-
nal of the Mechanical Behavior of Biomedical Materials,
Vol. 4, No. 3, 2011, pp. 417-422.
http://dx.doi.org/10.1016/j.jmbbm.2010.12.001
[6] J. Chenga, J. Yanga, X. Zhang, H. Zhong, J. Ma, et al.,
“High Temperature Tribological Behaviour of a Ti-46Al-
2Cr-2Nb Intermetallics,” Intermetallics, Vol. 31, 2012, pp.
120-126. http://dx.doi.org/10.1016/j.intermet.2012.06.013
[7] L. Bolzoni, E. M. Ruiz Navas, E. Neubauer and E. Gordo,
“Mechanical Properties and Micro Structural Evolution of
Vacuum Hot-Pressed Titanium and Ti-6Al-7Nb Alloy,”
Journal of the Mechanical Behaviour of Biomedical Ma-
terials, Vol. 9, 2012, pp. 91-99.
http://dx.doi.org/10.1016/j.jmbbm.2012.01.015
[8] K. Ida, Y. Tani, S. Tsutsumi, T. Togaya, T. Nambu, et al.,
“Clinical Application of Pure Titanium Crowns,” Journal
of Dental Materials, Vol. 4, No. 2, 1985, pp. 191-195.
http://dx.doi.org/10.4012/dmj.4.191
[9] B. Bergman, C. Bessing, G. Ericson, P. Lundquist, H.
Nilson, et al., “A 2-Year Follow-Up Study of Titanium
Crowns,” Acta Odontologica Scandinavica, Vol. 48, No.

Friction and Wear Behavior of Ti-6Al-7Nb Biomaterial Alloy 383
2, 2011, pp. 113-117.
[10] T. Hirata, T. Nakamura, F. Takashima, T. Maruyama, M.
Taira, et al., “Studies on Polishing of Ag-Pd-Cu-Au Alloy
with Five Dental Abrasives,” Journal of Oral Rehabilita-
tion, Vol. 28, No. 8, 2011, pp. 773-777.
http://dx.doi.org/10.1046/j.1365-2842.2001.00737.x
[11] T. Kawazoe and K. Suese, “Clinical Application of Tita-
nium Crowns,” Dental Materials Journal, Vol. 30, No. 3,
1989, pp. 317-328.
[12] A. Kuroiwa and Y. Igarashi, “Application of Pure Tita-
nium to Metal Framework,” Nihon Hotetsu Shika Gakkai
Zasshi, Vol. 42, No. 4, 1998, pp. 547-558.
http://dx.doi.org/10.2186/jjps.42.547
[13] M. A. Khan, R. L. Williams and D. F. Williams, “In-Vitro
Corrosion and Wear of Titanium Alloys in the Biological
Environment,” Biomaterials, Vol. 17, No. 22, 1996, pp.
2117-2126.
http://dx.doi.org/10.1016/0142-9612(96)00029-4
[14] S. Tamilselvi, R. Murugaraj and N. Rajendran, “Electro-
chemical Impedance Spectroscopic Studies of Titanium
and Its Alloys in Saline Medium,” Material and Corro-
sion, Vol. 58, No. 2, 2007, pp. 113-119.
http://dx.doi.org/10.1002/maco.200603979
[15] S. Tamilselvi and N. Rajendran, “In Vitro Corrosion Be-
havior of Ti-5Al-2Nb-1Ta Alloy in Hanks Solution,”
Materials and Corrosion, Vol. 58, No. 4, 2007, pp. 285-
289. http://dx.doi.org/10.1002/maco.200604001
[16] A. Guitar, G. Vigna and M. I. Luppo, “Microstructure
and Tensile Properties after Thermo Hydrogen Processing
of Ti-6Al-4V,” Journal of Mechanical Behavior of Bio-
medical Materials, Vol. 2, No. 2, 2009, pp. 156-163.
http://dx.doi.org/10.1016/j.jmbbm.2008.06.002
[17] C. R. Ramos-Saenz, F. A. Sundaram and N. Diffoot-
Carlo, “Tribological Properties of Ti-Based Alloys in Si-
mulated Bone Implant Interface with Ringer’s Solution at
Fretting Contacts,” Journal of Mechanical Behavior of
Biomedical Materials, Vol. 3, No. 8, 2010, pp. 549-558.
http://dx.doi.org/10.1016/j.jmbbm.2010.06.006
[18] R. C. Browne, “Vanadium Poisoning from Gas Tur-
bines,” British Journal of Industrial Medicine, Vol. 2, No.
12, 1955, pp. 57-59.
[19] S.-G. Sjöberg, “Vanadium Dust, Chronic Bronchitis and
Possible Risk of Emphysema: A Follow-Up Investigation
of Workers at a Vanadium Factory,” Journal of Internal
Medicine, Vol. 154, No. 5, 1956, pp. 381-386.
[20] P. G. Laing, “Clinical Experience with Prosthetic Materi-
als: Historical Perspectives, Current Problems and Future
Directions. Corrosion and Degradation of Implant Mate-
rials,” ASTM-STP 684, B. C. Syrett and A. Acharya, Eds.,
American Society for Testing and Materials, 1979, pp.
199-211.
[21] M. Geetha, A. K. Singh, R. Asokamini and A. K. Gogia,
“Ti Based Biomaterials, the Ultimate Choice for Ortho-
paedic Implants—A Review,” Progress in Materials Sci-
ence, Vol. 54, No. 3, 2009, pp. 397-425.
http://dx.doi.org/10.1016/j.pmatsci.2008.06.004
[22] G. B. Van der Volt, E. Marani, S. Tio and F. A. De Wolff,
“Aluminum Neurotoxicity,” In: W. Graumann and J.
Drukker, Eds., “Histo- and Cyto-Chemistry as a Tool in
Environmental,” Toxicology, Fisher, Stuttgart, Germany,
1991, pp. 235-242.
[23] D. R. C. McLachlan, G. Farnees and I. T. Galin, “Bio-
logical Aspects of Metals and Metal Related Diseases,”
Ravan Press, New York, 1983.
[24] D. Scharnweber, “Degradation (in Vitro-in Vivo Corro-
sion),” In: J. A. Helsen and H. Jürgen Breme, Eds., Met-
als as Biomaterials, John Willey & Sons, London, 1998,
pp. 101-151.
[25] M. F. Lopez, L. Soriano, F. J. Palomares, M. Sanchez-
Agudo, G. G. Fuentes, et al., “Soft X-Ray Absorption
Spectroscopy Study of Passive and Oxide Layers of Tita-
nium Alloys,” Surface and Interface Analysis, Vol. 33,
No. 7, 2002, pp. 570-579.
http://dx.doi.org/10.1002/sia.1422
[26] C. Morand, M. F. Lopez, A. Gutierrez and J. A. Jimenez,
“AFM and SEM Characterization of Non-Toxic Vana-
dium-Free Ti Alloys Used as Biomaterials,” Applied Sur-
face Science, Vol. 220, No. 1-4, 2003, pp. 79-87.
http://dx.doi.org/10.1016/S0169-4332(03)00746-3
[27] M. F. Lopez, J. A. Jimenez and A. Gutierrez, “Corrosion
Study of Surface-Modified Vanadium-Free Titanium Al-
loys,” Electrochimica Acta, Vol. 48, No. 10, 2003, pp.
1395-1401.
http://dx.doi.org/10.1016/S0013-4686(03)00006-9
[28] M. F. Semlitsch, H. Weber and R. M. Streicher, “Joint
Replacement Components Made of Hot-Forged and Sur-
face-Treated Ti-6Al-7Nb Alloy,” Biomaterials, Vol. 13,
No. 11, 1992, pp. 781-888.
http://dx.doi.org/10.1016/0142-9612(92)90018-J
[29] E. Kobayashi, T. J. Wang, H. Doi, T. Yoneyama and H.
Hamanaka, “Mechanical Properties and Corrosion Resis-
tance of Ti-6Al-7Nb Alloy Dental Castings,” Journal of
Materials Science: Materials in Medicine, Vol. 9, No. 10,
1998, pp. 567-574.
http://dx.doi.org/10.1023/A:1008909408948
[30] E. Confortoa, B.-O. Aronssonb, A. Salitoc, C. Crestoud
and D. Caillard, “Rough Surfaces of Titanium and Tita-
nium Alloys for Implants and Prostheses,” Materials
Science and Engineering C: Biomimetic and Supramole-
cular systems, Vol. 24, No. 5, 2004, pp. 611-618.
[31] Brahim TLILI, “Caractérisation de Films durs Multicou-
ches Elaborés par Pulvérisation Magnétron. Influence des
Conditions d’Élaboration sur Leurs Propriété,” Le 9 Dé-
cembre 2010 École Doctorale No. 432: Sciences des Mé-
tiers de l’Ingénieur Doctorat ParisTech Pastel-00573968,
Version 1-6, 2011.
[32] Norme Internationale (F) Implants Chirurgicaux—Pro-
thèses Partielles et Totales de l’Articulation de la Han-
che—Partie 2, ISO 7206-2, Surfaces Articulaires Con-
stituées de Matériaux Métalliques, Céramiques et Plasti-
ques, 1996.
[33] J. F. Archard, “Contact and Rubbing of Flat Surfaces,”
Journal of Applied Physics, Vol. 24, No. 8, 1953, pp.
981-988. http://dx.doi.org/10.1063/1.1721448
[34] L. Avril, “Elaboration de Revêtements sur Acier Inoxy-
dable Simulation de la Fusion par Irradiation Laser Carac-

Friction and Wear Behavior of Ti-6Al-7Nb Biomaterial Alloy 384
térisation Structurale, Mécanique et Tribologique,” Thèse,
Ecole Nationale Superieure (432), n° d’ordre 2003-16.
[35] H. Paetzold and E. Ilinich, “Determination of the Dy-
namic Friction Coefficient of Cartilage with Different
Biomaterials,” Journal of Biomechanics, Vol. 41, No. S1,
2008.