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Ion Bombardment Treatments for Metallic and Polymeric Bio-medical Materials
Rafael J. Rodríguez
Rafael J. Rodríguez
Centro de Ingeniería Avanzada de Superficies, AIN, E-31191 Cordovilla-Pamplona (Spain).
Ion Bombardment Treatments
for Metallic and Polymeric
Bio-medical Materials
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Ion Bombardment Treatments for Metallic and Polymeric Bio-medical Materials
Rafael J. Rodríguez
1 Ion implantation in the frame of advanced surface treatments
2 Ion implantation treatment of metal alloys
3 Ion implantation treatment of polymers
4 Conclusions on bio-medical applications
PRESENTATION
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Ion Bombardment Treatments for Metallic and Polymeric Bio-medical Materials
Rafael J. Rodríguez
Coating Substrate
Coatings always change the dimensions of the pieces and have an abrupt transition Ion implantation does not change dimensions and has a smooth transition to the substrate
Implanted region
COATINGS
ION IMPLANTATION
TREATMENT STRATEGIES
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Rafael J. Rodríguez
EFFECTS OF ION BOMBARDMENT
Ion Implantation is a ballistic treatment.
Depending on the bombardment energy, the dominant effect on the surface can be very different:
• Coatings (E < 100 eV)
• Sputtering (100 eV < E < 1000 eV)
• Implantation (E > 10.000 eV)
Typical energies for Ion Implantation industrial surface treatment are between 10.000 eV and 200.000 eV
Coatings
100 eV
1.000 eV
100.000 eV
Sputtering
Ion Implantation
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Rafael J. Rodríguez
In all cases, the relevant parameters are:- Ion(s) to be implanted- Energy- Dose
ION BOMBARDMENT STRATEGIES
ION BEAM IMPLANTATION (II) PLASMA IMMERSION IMPLANTATION (PI3)
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Rafael J. Rodríguez
1 1 eVeV 10 10 eVeV 100 100 eVeV 1 1 keVkeV 10 10 keVkeV 100 100 keVkeV 1 1 MeVMeV 10 10 MeVMeV
dE/dE/dxdx
elastic
inelastic
STOPPING POWER
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Rafael J. Rodríguez
Subtrate atoms “Oxide” Implanted atoms
Disordered regionImplanted layer
Crystaline region
ION IMPLANTATION RESULT
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Ion Bombardment Treatments for Metallic and Polymeric Bio-medical Materials
Rafael J. Rodríguez
0 100 200 300 400 500 6000
2
4
6
8
10
1.5 1017 Si 200 KeV
6 1016 Si 110 KeV
3 1016 Si 55 KeV Total
% a
t.
Depth (nm)
Range and distribution of implanted ions can be calculated by using TRIM or PROFILE codes.
Codes help to:
• design the implantation
• design co-implantations
• estimate saturation limits
• estimate other effects:
• sputtering
• ionization...
SIMULATION OF THE ION IMPLANTATION RESULT
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Ion Bombardment Treatments for Metallic and Polymeric Bio-medical Materials
Rafael J. Rodríguez
Tem
pera
ture
1200ºC
1000ºC
800ºC
600ºC
400ºC
200ºC
0,1 µm 1 µm 10 µm 0,1 mm 1 mm 10 mm
Plasma S.
Plasma Nitriding
Surfacehardening
Nitriding
Weldcoating
CVD
PA-CVD
PVDIon Impl.
TD
Carbonitriding
Carburising
TEMPERATURE vs. THICKNESS
Thickness
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Ion Bombardment Treatments for Metallic and Polymeric Bio-medical Materials
Rafael J. Rodríguez
HARDNESS vs. THICKNESS10.000
5.000
2.000
1.000
500
200
0,1 µm 1 µm 10 µm 0,1 mm 1 mm 10 mm
Har
dnes
sH
V
Thickness
Ion Implant.
Nitriding
TD
Nitrocarburising
Plasma S.
Surface hardening
Weldcoating
PVD
CVD - Diamond
CVD
Carburising
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Rafael J. Rodríguez
Gas
Plasma
100 kV
Target
Targetchamber
Holder
Ion source Acceleration Chamber
Ion beam
Secondaryelectrons
For Nitrogen or other gas implantations it is enough to have:
• Gas ion source
• One acceleration step (100 keV)
• A target chamber with mechanical scanning
Again, the equipment operates at high vacuum (10-6 mbar)
NO MASS SEPARATION INDUSTRIAL ION IMPLANTER
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Rafael J. Rodríguez
TECVAC 223 Implanter
• Gas ion source
• No mass separation
• Beam intensities up to 3 mA
• Energies up to 100 keV
• Turbomolecular vacuum
• 2 axis mechanical scanning
• Automated control
NO MASS SEPARATION INDUSTRIAL ION IMPLANTER
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Rafael J. Rodríguez
Ion source
Magneticfield
WindowHeavy ionsFoccussing,
scanning, etc.
Ion beam
Treatmentchamber
Light ions
MASS SEPARATION INDUSTRIAL ION IMPLANTER
For all species implantation, a mass separation system is needed.
That lead to more complex and expensive equipment.
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Rafael J. Rodríguez
WHICKHAM IBS
AIN - ion implanter
• Freeman ion source
• Mass separation
• Beam currents up to 5 mA
• Beam energy up to 200 keV
• Cryogenic vacuum
• 5 axis mechanical scanning
• Automated control
MASS SEPARATION INDUSTRIAL ION IMPLANTER
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Rafael J. Rodríguez
H1
He2
Li3
Be4
B5
C6
N7
O8
F9
Ne10
Na11
Mg12
Al13
Si14
P15
S16
Cl17
Ar18
K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
Cs55
Ba56
La57
Hf72
Ta73
W74
Re75
Os76
Ir77
Pt78
Au79
Hg80
Tl81
Pb82
Bi83
Po84
At85
Rn86
Fr87
Ra88
Ac89
Ce58
Pr59
Nd60
Pm61
Sm62
Eu63
Gd64
Tb65
Dy66
Ho67
Er68
Tm69
Yb70
Lu71
Th90
Pa91
U92
Np93
Pu94
Am95
Cm96
Bk97
Cf98
Es99
Fm100
Md101
No102
Lr103
TYPICAL ELEMENTS TO BE IMPLANTED
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Rafael J. Rodríguez
PRACTICAL SURFACE ANALYSIS: GD-OES
Dischargechamber
DC orRF
Rowlandcircle
Gas (Ar)
Detectors (PM)
Secondarywindows
Diffractiongrid
Primarywindow
Spectrometer
Glow Discharge Optical Emission Spectroscopy (GD-OES) allows to obtain precision quantitative composition profiles in few minutes. No UHV is required. Just well polished flat implanted samples.
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Rafael J. Rodríguez
0,0 0,1 0,2 0,3 0,4 0,5
0
10
20
30
40
50
60
70
80
90
100
110
N por RF
Ti por RF
N por DC
Ti por DC
% a
tóm
ico
Depth (μ m )
GD-OES analysis of a Ti sample implanted with 8*1017 N2+
PRACTICAL SURFACE ANALYSIS: GD-OES
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Ion Bombardment Treatments for Metallic and Polymeric Bio-medical Materials
Rafael J. Rodríguez
Friction coefficient before and after implantation
0
0,2
0,4
0,6
0,8
1
AISI 316 Al 7075 Tit anio
Coe
ficie
nte
de
Fric
ción
Sin implantarImplantado
Hardness before and after implantation
0
1000
20003000
4000
5000
AISI 316 Al 7075 TitanioDure
za U
nive
rsal
(N
/mm
2 )
Sin implantarImplantado
EFFECTS ON THE IMPLANTED MATERIALS
INCREASE OF HARDNESS• Precipitation of nitrides, carbides, etc.• New alloys formation• Cross-linking of polymersBETTER TRIBOLOGICAL BEHAVIOUR• More homogeneous / coherent oxide layersRESISTANCE TO ROLLING FATIGUE• Compressive tensions at the surfaceCORROSION RESISTANCE• New alloys with better resistance• Better adhered and compact oxide layersOXIDACION RESISTANCE• Surface doping with lanthanide elements
R. Rodríguez, A. Sanz, A. Medrano and J.A. García-Lorente.Tribological properties of ion implanted Aluminium alloys.Vacuum 52 (1999), 187.
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Rafael J. Rodríguez
ELEMENTS THAT CAN BE IMPROVED BY NITROGEN IMPLANTATION
H1
He2
Li3
Be4
B5
C6
N7
O8
F9
Ne10
Na11
Mg12
Al13
Si14
P15
S16
Cl17
Ar18
K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
Cs55
Ba56
La57
Hf72
Ta73
W74
Re75
Os76
Ir77
Pt78
Au79
Hg80
Tl81
Pb82
Bi83
Po84
At85
Rn86
Fr87
Ra88
Ac89
Ce58
Pr59
Nd60
Pm61
Sm62
Eu63
Gd64
Tb65
Dy66
Ho67
Er68
Tm69
Yb70
Lu71
Th90
Pa91
U92
Np93
Pu94
Am95
Cm96
Bk97
Cf98
Es99
Fm100
Md101
No102
Lr103
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Rafael J. Rodríguez
SURFACE MECHANICAL PROPERTIES: HU and E
Universal Hardness (HU) can be
measured from 1mN, till 1000 mN of
maximum load by using a
Fischeroscope microindentation
equipment. At 2mN, the indentation
depth in metals is less than 0,2 microns
Elastic and plastic hardness as well as
elastic modulus can be obtained from
the load – unload curves.
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Rafael J. Rodríguez
0,0 0,5 1,0 1,5 2,0
0,02
0,04
0,06
0,08
0,10
0,12
0,14
sin implantar
4e17 N+/cm2
8e17 N+/cm2
4e17 N2+/cm2
8e17 N2+/cm2
Prof
undi
dad
(μm
)Carga (mN)
UNIVERSAL HARDNESS TESTS ON IMPLANTED SURFACES
J. A. García, A. Guette, A. Medrano, C. Labrugere, M. Rico, M. Lahaye, R. Sánchez, R. Martínez and R. J. Rodríguez: Nitrogen ion implantation on Group IV metals: chemical, structural and tribological study, Vacuum 64, 343 (2002).
N+ Implanted Zirconium at different doses
LOW LOADS:
Low indentation loads are needed because the implanted region is thinner than few tenths of micron.
DEFFECTLESS SURFACES:
Hardness tests can be carried out only on mirror polished surfaces.
BETTER ON SOFT METALS:
Changes in hardness are more visible on soft metals.
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Rafael J. Rodríguez
02468
10121416
Al-7
075 Ti Zr Hf V N
b Ta Cr
Mo W
ReferenceLow doseHigh dose
HARDNESS (GPa) OF NITROGEN IMPLANTED METALS
J. A. García, A. Guette, A. Medrano, C. Labrugere, M. Rico, M. Lahaye, R. Sánchez, R. Martínez and R. J. RodríguezNitrogen ion implantation on Group IV metals: Chemical, structural and tribological study. Vacuum 64 (2002), 343.J. A. García, R. J. Rodríguez, A. Medrano, R. Sánchez, M. Rico, R. Martínez, B. Lerga, C. Labrugere, M. Lahaye, and A. GuetteStudy of the tribological modifications induced by nitrogen implantation on group V metals. Surface and Coatings Technology 158-159 (2002), 653.R. Martínez, J. A. García, R. J. Rodríguez, B. Lerga, C. Labrugere, M. Lahaye, and A. GuetteStudy of the tribological modifications induced by nitrogen implantation on groupVI: Cr, Mo and W. Surface and Coatings Technology 174-175 (2003), 1253.
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APPLICATIONS FOR HIP AND KNEE PROSTHESIS
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Rafael J. Rodríguez
ION IMPLANTATION ON POLYMERSThe main effect of ion implantation on polymers is the increase in hardness due to the cross linking of polymer chains because the ionisation produced by ion bombardment.
The effect is more intense for light and energetic ions because they loss energy preferentially by ionisation (inelastic stopping power), have minor chain breakage effects (elastic stopping power) and goes deeper.
Nitrogen implantation on Polyethylene
Helium implantation on Polyethylene
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Rafael J. Rodríguez
INCREASE OF POLYMER HARDNESS
BY HIDROGEN IMPLANTATION
LOW DOSE IMPLANTATION ON POLYCARBONATE:
A low dose implantation is enough to produce a dramatic increase of hardness.
HU vs. HV:
Elastic recovery reach the 100% for a implanted surface. That would lead to an apparently infinite HV.
R. Rodríguez, J. A. García, R. Sánchez, A. Pérez, Blas Garrido and J. Morante:Modification of surface mechanical properties of polycarbonate by ion implantation.Surface and Coatings Technology 158-159 (2002), 636.
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Universal Hardness of samples implanted with 1e16 ion/cm2
0
100
200
300
400
500
600
Sinimplantar
N+ H2+ D2+ H+ D+
Implanted ions
N/m
m2
2 mN5 mN10 mN25 mN200 mN
Reference
ION IMPLANTATION OF POLYCARBONATE
R. Rodríguez, J. A. García, R. Sánchez, A. Pérez, Blas Garrido and J. Morante:Modification of surface mechanical properties of polycarbonate by ion implantation.Surface and Coatings Technology 158-159 (2002), 636.
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Rafael J. Rodríguez
a b c d
Visual inspection of samples after the implantation with different doses and ions shows that:
• After the treatments a change in the surface color was observed, the higher the dose the darker the color.
• Nitrogen implantation produced a darker surface than Helium.
IMPLANTATION OF UHMPWD SAMPLES
a) UHMWPE sample implanted with 1x1016 ions/cm2 of N.
b) UHMWPE sample implanted with 5x1015 ions/cm2 of N.
c) UHMWPE sample implanted with 5x1015 ions/cm2 of He.
d) Untreated UHMWPE sample.
UHMWPE SAMPLES AFTER IMPLANTATION
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NITROGEN EFFECTS ON UHMWPE
The TRIM stopping power calculations shows that:
• The range of Nitrogen implantation on UHMWPE, at 90 keV, is about 400 nm.
• A 80,5% of the bombardment energy is lost through inelastic mechanism and lead to ionization of the polymer chains.
• The other 19,5% of the energy is lost through elastic mechanism, leading to chain breakdown.
TRIM CALCULATION OF THE NITROGEN RANGE ON UHMWPE AND ENERGY LOSS MECHANISMS
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HELIUM EFFECTS ON UHMWPEThe TRIM stopping power calculations shows that:
• The range of Helium implantation on UHMWPE, at 90 keV, is about 1000 nm.
• A 94,5% of the bombardment energy is lost through inelastic mechanism and lead to ionization of the polymer chains.
• The other 5,5% of the energy is lost through elastic mechanism, leading to chain breakdown.
TRIM CALCULATION OF THE HELIUM RANGE ON UHMWPE AND ENERGY LOSS MECHANISMS
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RESULTS OF INDENTENTION TESTS
0.2 0.4 0.6 0.8 1.0 1.2 1.4
30
40
50
60
70
80
90
100
110
SinImplantar
He 5x1015iones/cm2
Muestra circular 1 100 KGy TT 130º
Dur
eza
Uni
vers
al (N
/mm
2 )
Profundidad (μm)
UNIVERSAL HARDNESS IN (N/mm2)
SAMPLE 2 mN
UNTREATED 34 ± 2
IMPLANTATION 1 - N 5x1015 43 ± 4
IMPLANTATION 2 - N 1x1016 42 ± 8
IMPLANTATION 3 - He 5x1015 53 ±6
IMPLANTATION 4 - He 1x1016 59 ± 5
IMPLANTATION 5 - He 2x1016 40 ± 9
PROFILE OF HARDNESS vs. DEPTH FOR IMPLANTATION 4 AND UNTREATED SAMPLE HU at 2mN OF FINAL LOAD
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0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.620
40
60
80
100
120
140
160
180 Implantaciones sobre TT 130º
He 1x1016iones/cm2
He 5x1015iones/cm2
N 1xE16 iones/cm2
Sin implantar
Dur
eza
Uni
vers
al (N
/mm
2 )
Profundidad (μm)
RESULTS OF INDENTENTION TESTS
COMPARISON OF HARDNESS PROFILES OF THE IMPLANTATIONS CARRIED OUT ON UHMWPE SAMPLES WITH PRETREATMENT AT 130ºC
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0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.620
40
60
80
100
120
140
160
180 Implantaciones sobre TT 150º
He 2x1016 iones/cm2
N 1x1016iones/cm2
N 5x1015iones/cm2
Sin Implantar
Dur
eza
Uni
vers
al (N
/mm
2 )
Profundidad (μm)
RESULTS OF INDENTATION TESTS
COMPARISON OF HARDNESS PROFILES OF THE IMPLANTATIONS CARRIED OUT ON UHMWPE SAMPLES WITH PRETREATMENT AT 150ºC
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0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,620
40
60
80
100
120
140
160
180
He 1x1016atm/cm2
He 5x1015 atm/cm2
N 1x1016atm/cm2
N 5x1015atm/cm2
sin implantar
Dur
eza
Uni
vers
al (N
/mm
2 )
Profundidad (μm)
RESULTS OF INDENTENTION TESTS
COMPARISON OF HARDNESS PROFILES OF THE IMPLANTATIONS WITH ALL THE DIFFERENT DOSES AND IONS
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ELASTIC MODULUS AND ELASTIC WORK
UHMWPE + PRETREATMENT 130ºC
0
0,2
0,4
0,6
0,8
1
1,2
ref 1e16 N 5e15 He 1e16 He
E/(1
-v2)
(Gpa
)
UHMWPE+PRETREATMENT 130ºC
01020304050607080
ref 1e16 N 5e15 He 1e16 He
%W
e
(a) ELASTIC MODULUS AND (b) % OF ELASTIC WORK OF THE IMPLANTED SAMPLES, MEASURED AT FINAL LOAD OF 2mN.
a b
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PLASMA IMMERSION ION IMPLANTATION
Plasma Immersion Ion Implantation (PI3) has been claimed as the future solution of the ion implantation problems (line-of-light process, sequential process...).
The no directional intense bombardment can increase the temperature. That would lead to a combined ballistic - diffusionalprocess.
PI3 is an excellent alternative to conventional processes for treating large series of small complex shape components like stents
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Stents are being extensively employed in many surgical operations.
There are some concerns about the stability of stents that have to remain implanted in the human body. It is worth to mention the effects of metal ion migration (possible toxicity).
To prevent the migration of undesired ions, (e.g. Nickel) a possible technique is the creation of an oxide barrier. Ion implantation of Oxygen could be a good strategy, but the ordinary line-of-sight ion implantation process is not adequate to implant thousands of small components.
APLICATIONS ON STENTS
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OXYGEN PLASMA IMMERSION IMPLANTATION ON STEEL
0,00 0,02 0,04 0,06 0,080
10
20
30
40
50
60
70
80 O2
10kV 20kV 30kV
%A
t
Profundidad (μm)0,00 0,02 0,04 0,06 0,08
0
2
4
6
8
10
12
14
16
18
20Ni
10kV 20kV 30kV
%A
t
Profundidad (μm)
PI3 leads to saturated implantation profiles, which goes deeper as a function of the energy.
In the case of Oxygen implanted on stainless steel, it can be shown how the oxide barrier confines the Nickel at increasing depth.
Centre of AdvancedSurface Engineering
BIOMEDICAL SURFACES 2006 Churchill College, Cambridge, UK, 10/10/2006 Page 38/40
Ion Bombardment Treatments for Metallic and Polymeric Bio-medical Materials
Rafael J. Rodríguez
II
PI3
In spite of its functional advantages, PI3 can lead to more relevant surface heating as well as to increases of roughness (e.g., more than 10 times in the case of Al alloys)
PLASMA IMMERSION ION IMPLANTATION
Centre of AdvancedSurface Engineering
BIOMEDICAL SURFACES 2006 Churchill College, Cambridge, UK, 10/10/2006 Page 39/40
Ion Bombardment Treatments for Metallic and Polymeric Bio-medical Materials
Rafael J. Rodríguez
FINAL REMARKS
• Ion Implantation has demonstrated to be an effective technique for the prevention of wear, excessive friction and some oxidation and corrosion problems of metal alloys employed in medical implants and devices (stainless steel, Titanium alloys, CrCo, NiTinol...).
• In addition, other benefical effects of ion implantation have been reported: implantation of CO+ ions seems to facilitate the bone growth and integration. Theimplantation of Ag+ has bacteriocide effects. The implantation of oxigen allows tocreate difusional barriers for toxic ions...
• The ion implantation treatment of polymers is still more promising, and the requireddose is 10 – 20 times smaller.
• Ion implantation is economically affordable when size and geometry collaborate to short times of treatment per unit. Future developments like PI3 could lead to even cheaper treatments.
Centre of AdvancedSurface Engineering
BIOMEDICAL SURFACES 2006 Churchill College, Cambridge, UK, 10/10/2006 Page 40/40
Ion Bombardment Treatments for Metallic and Polymeric Bio-medical Materials
Rafael J. Rodríguez
AIN - Centre of Advanced Surface Engineering
• Private technological center, founded in 1963• Association of 157 companies• Employees (2005): 121 (15 AIN - CIAS)• Clients (2005): 1085 (90 AIN - CIAS)
e-mail: [email protected]