Diamond-like carbon coatings deposited by vacuum arc in artificial hip joints

179 Pages·2013·5.44 MB·English

Diamond-like carbon coatings deposited by vacuum
arc in artificial hip joints
Dissertation
zur Erlangung eines Doktorgrades
im
Fachbereich D – Architektur, Bauingenieurwesen, Maschinenbau,
Sicherheitstechnik
der
Bergischen Universität Wuppertal
‐ Maschinenbau‐
vorgelegt von
Ying Ren
aus Shanxi (23.10.1982)
Wuppertal 2013
Dedication

To my God.
Declaration
Declaration
I declare that the work in this dissertation was carried out in accordance with the regulation
of University of Wuppertal. I declare that I have written it independently and have used only the
tools indicated in the dissertation. The work is original, except where indicated by special
literature in the text and it has not been submitted elsewhere for examination. In addition for me
no previous PhD applications have been unsuccessful.

Hiermit erkläre ich, Ying Ren, dass ich die vorliegende Arbeit selbständig ohne unerlaubte
fremde Hilfe angefertigt habe und keine anderen Quellen und Hilfsmittel genutzt habe, als im
Literaturverzeichnis angegeben. Alle Stellen in dieser Arbeit, die dem Wortlaut oder Sinn nach
anderen Werken entnommen wurden, habe ich in jedem einzelnen Fall unter Angabe der Quelle
als Entlehnung kenntlich gemacht. Die Arbeit ist noch nicht an anderer Stelle als
Prüfungsleistung vorgelegt worden. Es wurde kein Promotionsverfahren ohne Erfolg beendet.
Die Dissertation kann wie folgt zitiert werden:
urn:nbn:de:hbz:468-20131023-124239-7
[http://nbn-resolving.de/urn/resolver.pl?urn=urn%3Anbn%3Ade%3Ahbz%3A468-20131023-124239-7]
Abstract
Abstract
For biomedical application in the field of artificial hip joints diamond-like carbon (DLC)
coatings have been widely studied due to their excellent mechanical, tribological and biological
properties. At present the lifetime of such joints is just about 15 years and some (10%) of
patients require second replacement. In consequence, it is currently an urgent need to extend the
life expectancy especially for younger patients under 50 years old. As is well known, the wear
particles as the main factor limiting the life expectancy of hip joints have attracted more and
more interest, in particular, the amount of wear particles. However, it is rare to see the reports
about wear particle size distribution.
The key contribution of this dissertation is a new approach-design of wear particle size
distribution, which is an initial and important step of DLC research in artificial hip joint field. In
addition, DLC coating is grown by a new deposition technique based on the vacuum arc, which
allows the transition from cathodic to anodic operation mode by adjusting the anode-cathode
diameter ratio. The main aim of this dissertation is to investigate the influence of deposition
parameters on the wear particle size distribution, as well as the structure and tribological
properties of DLC coatings. It is shown that it is possible to reduce the wear particle size by
optimization of the deposition parameters.
Für biomedizinische Anwendungen im Bereich künstlicher Hüftgelenke wurden DLC-
(diamond like carbon) Schichten hinsichtlich ihrer ausgezeichneten mechanischen,
tribologischen und bioinerten Eigenschaften weitreichend untersucht.
Gegenwärtig beträgt die Lebensdauer dieser Implantate in etwa 15 Jahre, so dass ca. jeder
zehnte Patient einen weiteren Austausch benötigt (Revisionsoperation). Folglich ist es, besonders
für jüngere Patienten unter 50 Jahren von großer Wichtigkeit, die Standzeit dieser
Gelenkimplantate zu erhöhen.
Da Abriebpartikeln bekanntermaßen der Faktor sind, welcher die Standzeiten dieser
Hüftimplantate am meisten beschränkt, rückten diese (speziell in ihrer Quantität) in der
Vergangenheit zunehmend in den Fokus der wissenschaftlichen Betrachtung.
Ungeachtet dessen gibt es nur wenige Veröffentlichungen über die Partikelgrößenverteilung.
I
Der Schlüsselbeitrag dieser Dissertation ist ein neuer Ansatz zur Beeinflussung der
Partikelgrößenverteilung, welcher einen innovativen und wichtigen Schritt in der Erforschung
von DLC-Schichten für künstliche Hüftgelenkimplantate darstellt.
Hierbei kommt ein neuartiges Beschichtungsverfahren, welches auf dem
Vakuum-Lichtbogenverfahren basiert, zum Einsatz. Durch Variation der Elektrodendurchmesser
erlaubt es dieses Verfahren, die DLC-Schichten sowohl vom kathodischen als auch vom
anodischen Lichtbogen abzuscheiden.
Hauptziele dieser Dissertation sind sowohl die Erforschung des Einflusses der
Beschichtungsparameter auf die Partikelgrößenverteilung sowie auch die strukturellen und
tribologischen Eigenschaften der DLC-Schichten.
Es wird gezeigt, dass es möglich ist, die Größe der Abriebpartikeln durch Optimierung der
Beschichtungsparameter zu reduzieren.

II
Contents
Contents
List of Figures ......................................................................................................................... VI
List of Tables ............................................................................................................................ X
1. Introduction .......................................................................................................................... 1
1.1 The challenge ................................................................................................................ 1
1.2 Objectives and contributions ......................................................................................... 2
1.3 Research discussion ...................................................................................................... 3
1.3.1 Problem statement .............................................................................................. 3
1.3.2 Assumptions and their motivation ....................................................................... 5
1.4 Thesis organization ....................................................................................................... 6
References .......................................................................................................................... 7
2. DLC coatings background .................................................................................................. 10
2.1 Structure and properties of DLC coatings .................................................................... 10
2.1.1 Structure of DLC coatings ................................................................................ 10
2.1.2 Properties of DLC coatings ............................................................................... 12
References ........................................................................................................................ 13
2.2 Applications of DLC coatings ..................................................................................... 15
2.2.1 Biomedical applications.................................................................................... 15
2.2.2 Other applications............................................................................................. 17
References ........................................................................................................................ 20
2.3 Deposition techniques of DLC coatings....................................................................... 25
2.3.1 Physical vapor deposition of DLC coatings ...................................................... 25
2.3.2 CVD and other deposition techniques of DLC coatings .................................... 29
References ........................................................................................................................ 30
3. Hip joint replacement background .................................................................................... 34
3.1 Introduction of normal hip joint and artificial hip joint ................................................ 34
3.1.1 Composition of hip joint ................................................................................... 34
3.1.2 Wear particles ................................................................................................... 35
3.2 Classification of artificial hip joint .............................................................................. 37
3.2.1 Metal femoral heads articulating against UHMWPE cups ................................. 37
3.2.2 Ceramic femoral heads articulating against UHMWPE cups ............................. 37
3.2.3 Metal femoral heads articulating against metal cups ......................................... 38
3.2.4 Ceramic femoral heads articulating against ceramic cups .................................. 39
3.2.5 DLC coated artificial hip joint .......................................................................... 40
3.3 Adhesion and interface layers in biomedical materials ................................................. 41
References ........................................................................................................................ 44
4. Experimental methods for characterization of DLC coatings .......................................... 49
III
4.1 Morphology and structure of DLC coatings ................................................................. 49
4.1.1 Coating thickness and roughness ...................................................................... 49
4.1.2 Scanning electron microscopy (SEM) ............................................................... 49
4.1.3 Energy dispersive X-ray spectroscopy (EDX) ................................................... 51
4.1.4 Raman spectroscopy ......................................................................................... 52
4.2 Tribological evaluation of DLC coatings ..................................................................... 58
4.3 Cavitation erosion test ................................................................................................. 59
4.4 Particle size distribution analysis ................................................................................. 61
References ........................................................................................................................ 64
5. Experiments for deposition of interface layer and DLC coatings ..................................... 67
5.1 Deposition of interface layer (Ti) by cathodic arc evaporation ..................................... 67
5.1.1 Deposition setup (Cathodic arc evaporation) ..................................................... 67
5.1.2 Deposition Process ........................................................................................... 68
5.2 Relationship between deposition pressure and arc voltage and current ......................... 70
5.3 Deposition of DLC coatings by new vacuum arc equipment ........................................ 72
5.3.1 Deposition setup (Transition between the cathodic arc and anodic arc) ............. 72
5.3.2 Deposition Process ........................................................................................... 73
References ........................................................................................................................ 74
6. Parameters of analysis of Raman spectra and wear tests ................................................. 75
6.1 Analysis of Raman spectra .......................................................................................... 75
6.2 Parameters of tribological test ..................................................................................... 80
6.3 Parameters of cavitation erosion test ........................................................................... 87
6.4 Parameters of particle size distribution analysis ........................................................... 91
References ........................................................................................................................ 96
7. Influence of substrate bias on the particle size distribution of DLC coatings .................. 99
7.1 Anode-cathode diameter ratio of d /d = 1/3 ................................................................ 99
a c
7.1.1 Density and deposition rate of DLC coatings .................................................... 99
7.1.2 Raman spectra of DLC coatings ..................................................................... 100
7.1.3 Tribological properties of DLC coatings ......................................................... 103
7.1.4 Particle size distribution of DLC coatings ....................................................... 104
7.1.5 Conclusion ..................................................................................................... 107
7.2 Anode-cathode diameter ratio of d /d = 1/1 .............................................................. 108
a c
7.2.1 Density and deposition rate of DLC coatings .................................................. 108
7.2.2 Raman spectra of DLC coatings ..................................................................... 109
7.2.3 Tribological properties of DLC coatings ......................................................... 112
7.2.4 Particle size distribution of DLC coatings ....................................................... 113
7.2.5 Conclusion ..................................................................................................... 115
7.3 Anode-cathode diameter ratio of d /d = 3/1 .............................................................. 116
a c
7.3.1 Density and deposition rate of DLC coatings .................................................. 116
7.3.2 Raman spectra of DLC coatings ..................................................................... 117
7.3.3 Tribological properties of DLC coatings ......................................................... 121
IV
Contents
7.3.4 Particle size distribution of DLC coatings ....................................................... 122
7.3.5 Conclusion ..................................................................................................... 124
References ...................................................................................................................... 125
8. Influence of d /d on the particle size distribution of DLC coatings ............................... 127
a c
8.1 Substrate bias at –250 V ............................................................................................ 128
8.1.1 Density and deposition rate of DLC coatings .................................................. 128
8.1.2 Raman spectra of DLC coatings ..................................................................... 128
8.1.3 Particle size distribution of DLC coatings ....................................................... 130
8.1.4 Conclusion ..................................................................................................... 131
8.2 Substrate bias at –500 V ............................................................................................ 131
8.2.1 Density and deposition rate of DLC coatings .................................................. 131
8.2.2 Raman spectra of DLC coatings ..................................................................... 132
8.2.3 Particle size distribution of DLC coatings ....................................................... 133
8.2.4 Conclusion ..................................................................................................... 134
8.3 Substrate bias at –750 V ............................................................................................ 135
8.3.1 Density and deposition rate of DLC coatings .................................................. 135
8.3.2 Raman spectra of DLC coatings ..................................................................... 136
8.3.3 Particle size distribution of DLC coatings ....................................................... 137
8.3.4 Conclusion ..................................................................................................... 138
8.4 Substrate bias at –1000 V .......................................................................................... 138
8.4.1 Density and deposition rate of DLC coatings .................................................. 138
8.4.2 Raman spectra of DLC coatings ..................................................................... 139
8.4.3 Particle size distribution of DLC coatings ....................................................... 140
8.4.4 Conclusion ..................................................................................................... 140
References ...................................................................................................................... 141
9. Influence of substrate bias and d /d on adhesion (Cavitation erosion) .......................... 142
a c
9.1 Anode-cathode diameter ratio of d /d = 1/3 .............................................................. 142
a c
9.2 Anode-cathode diameter ratio of d /d = 1/1 .............................................................. 145
a c
9.3 Anode-cathode diameter ratio of d /d = 3/1 .............................................................. 148
a c
References ...................................................................................................................... 152
10. Conclusion and Future Work ......................................................................................... 153
10.1 Contributions .......................................................................................................... 153
10.2 Conclusions ............................................................................................................ 154
10.3 Limitations .............................................................................................................. 156
10.4 Future work............................................................................................................. 158
References ...................................................................................................................... 160
Acknowledgments ................................................................................................................. 161
Appendix ............................................................................................................................... 163
Lebenslauf ............................................................................................................................. 166
V
List of Figures
Figure 1.1 Tribological process diagram .............................................................................................................. 5
Figure 2.1 The sp3, sp2, sp1 hybridised bonding [1] ........................................................................................... 10
Figure 2.2 Carbon structure in (a) diamond, (b) graphite and (c) amorphous diamond-like carbon [2-4] ..........11
Figure 2.3 Ternary phase diagram for various DLC coatings with respect to sp3, sp2 and
hydrogen contents [7] ........................................................................................................................11
Figure 2.4 DLC coated products (a) Stent [1] (b) Left ventricular assist device heart pump [2]
(c) artificial joint [2] (d) Ankle joint [3] (e) Hip Joint [4] ................................................................ 15
Figure 2.5 DLC coated products (a) End mill (b) Step drill (c) Engine piston (d) Gears
(e) Engine tappets [58] ..................................................................................................................... 18
Figure 2.6 Hard disk architecture [59] ............................................................................................................... 18
Figure 2.7 DLC coated IRST Dome [68] ........................................................................................................... 19
Figure 2.8 Coaxial speaker (DLC-coated titanium centre cap) [71] .................................................................. 20
Figure 2.9 Schematic of cathodic vacuum arc [1] .............................................................................................. 26
Figure 2.10 Schematic diagram of a various filters: (a) 90º filter (b) 45º filter (c) S-filter [23]......................... 27
Figure 2.11 Schematic diagram of anodic vacuum arc deposition setup [32] .................................................... 28
Figure 3.1 The normal hip joint and arthritic hip joint [1] ................................................................................. 34
Figure 3.2 Schematic of a normal hip joint (left [2]), corresponding artificial hip joint (right [3]) ................... 35
Figure 3.3 Metal-on-UHMWPE hip joint [25] ................................................................................................... 37
Figure 3.4 Ceramic-on-UHMWPE hip joint [25] ............................................................................................... 38
Figure 3.5 Metal-on-Metal hip joint [25] ........................................................................................................... 39
Figure 3.6 Ceramic-on-Ceramic hip joint [37] ................................................................................................... 40
Figure 4.1 Schematic diagram of scanning electron microscope (SEM) ........................................................... 50
Figure 4.2 Interaction between electron beam and surface layer of the specimen ............................................. 50
Figure 4.3 Vibrational energy level diagram of Rayleigh scattering and Raman scattering............................... 53
Figure 4.4 Characteristic Raman spectra of some carbon-based materials at 514.5 nm [19,20] ........................ 54
Figure 4.5 Amorphization trajectory [13] ........................................................................................................... 55
Figure 4.6 Schematic diagram of influence on the Raman spectra .................................................................... 57
Figure 4.7 The tribological test setup [30] ......................................................................................................... 58
VI