MOSCOW INSTITUTE OF STEEL AND ALLOYS

1. MOSCOW INSTITUTE OF STEEL AND ALLOYS

2. Ti-BASED MULTICOMPONENT COATINGS FOR LOAD-BEARING MEDICAL APPLICATIONS D.V. SHTANSKY, E.A. LEVASHOV, I.A. BASHKOVA, A.N. SHEVEIKO, F.V. KIRYUKHANTSEV-KORNEEV, M.I. PETRZHIK Cancer Research Center of RAMS N.A. GLOUSHANKOVA, M.A. KHARITONOVA, T.G. MOIZHESS, I.V. RESHETOV

3. BIOCOMPATIBLE MULTICOMPONENT COATINGS FOR LOAD-BEARING MEDICAL APPLICATIONS Ti Alloys and Stainless Steel Poor biocompatibility Stress shielding (difference in stiffness of bone and implant) Release metal ions (cause toxic reaction) and wear debris (loosening of implant fixation) Traditional wayincreasing bioactivity– deposition of HA (Ca10(PO4)6(OH)2) Inorganic additives improve mechanical and tribological properties, reduce elastic modulus and induce bioactivity of implant surface ZrO2,SiO2,CaO,TO2 TiCx, TiCxNy- high hardness, wear and corrosion resistance A new approach to combine excellent mechanical and tribological properties with biocompatibility and non-toxicity by doping the TiCx and TiCxNx films with inorganic additives

4. Ti, Ca, Zr, Si, Mn, C, N, O, and P are suitable elements to develop new advanced bio ceramics. TiN - high hardness, remarkable resistance to wear and corrosion. TiO2 - excellent biocompatibility, blood compatibility, and corrosion resistance. C or DLC (metastable form of amorphous carbon) - hard, wear- and corrosion-resistant material which possesses low friction, chemical inertness and moderate biocompatibility. Surfaces containing Ca and/orP induce osteoinduction of new bones and become bioactive. Si - stimulates the growth of human osteoblast-like cells, bone mineralization and soft tissue development. The formation of bone-like apatite is induced by functional groups, such as Si-OH, Ti-OH, Zr-OH, -COOH, PO4H2. Hydroxyapatite (Ca10(PO4)3(OH)2) - close similarity to the chemical and mineral components of teeth and bone. Some ceramics, CaO-SiO2, CaSiO3, CaO-MgO-2SiO2 possess good bioactivity and biocompatibility. ZrO2 - improve mechanical properties without substantial compromise in biocompatibility.

5. Average implant lifetime 10-20 years • Main Requirements • High hardness • Low Young’s modulus close to bone • Excellent fatigue and tensile strength • Superior corrosion and wear resistance • Low friction • Good adhesion to implant surface • Negative surface charge in the body fluid • Bioactive surface • Biocompatibility • Low level of cytotoxicity • Extended lifetime of the implants • Accelerated self-adaptation of the implant material in the living tissue Artificial hip joint

6. Magnetron Sputtering and Ion Implantation Assisted Magnetron Sputtering In vitro Experiments Attachment, spreading and proliferation of cells Morphometric analysisand actin cytoskeleton organization Structural CharacterizationXRD, TEM, SEM, SFM, XPS, AES Multifunctional Coatings SHS Composite Targets In Vivo Experiments Population and differentiation of cells (leucocytes, macrophages, lymphocytes, giant multinucleated cells), adhesion between capsule and film surface Physical, Mechanical and Tribological Properties {Hardness (H), Elastic Modulus (E), Elastic Recovery (We), Surface Charge, Critical Load (Lc), Friction Coefficient (), Wear Rate (Wr)}

7. 1. Composite SHS-Targets Advantages of Composite and FGM targets: The flow of both metal and non-metal atoms and ions is realized from the target to the substrate; FGM targets exhibit required toughness and thermal resistance (resistance to thermal-cycling during high-power magnetron sputtering) needed for PVD targets Composite Targets (TiC0.5 + CaO) (TiC0.5 + ZrO2) (TiC0.5 +CaO+TiO2) TiC0.5+HAP (Ca10(PO4)6(OH)2) TiC0.5+CaO+KMnO4 (Ti5Si3 + ZrO2) (TiC0.5 + Nb2C)

8. Ar / Ar+N2 Magnetron 1 Ion etcher Heater Ion implantor UBIAS Substrate Shutter Magnetron 2 Pumping Ion Implantation Assisted Magnetron Sputtering Accelerating voltage – 20-40 kV Current - 10 mA Flux of ions - 1.5.1014 ions/(cm2 s)

9. Coating characteristics

10. Coating characteristics

11. Ti-Ca-C-O-N Ti-Zr-C-O-N Ti-Nb-C-N Ti-Nb-C-N Load 5 N – hard alloy substrate, load 1 N – titanium alloy substrate FRICTION COEFFICIENTS IN AIR

12. IMPORTANCE OF LOW YOUNG’S MODULUS Resistance to plastic deformation – H3/E2(T.Y. Tsui et al., Mat.Res.Soc.Symp.Proc. 383 (1996) 447. Long elastic strain to failure – H/E, indicator of good wear resistance (A. Leyland et al., Wear 246 (2000) 1.

13. Cytocompatibility in vitro Biocompatibility in vivo Evolution of biocompatibility Cell function tests fist phase of cell/material interactions Cytotoxicity tests Osteoblast differentiation Attachment Adhesion Spreading Proliferation Actin cytoskeleton staining Population of cells Inflammatory response Osteoblast cell growth

14. Cell cultures Fibroblasts and epithelial cells (connective tissue forming cells) Osteoblasts (bone-forming cells) Macrophages cells (large white blood cell that engulf foreign bodies) Leucocytes, lymphocytes, giant multinucleated cells (responsible cells for the inflammatory reaction)

15. IAR-2 (a) (b) (c) Rat-1 (d) (e) (f) Actin cytoskeleton (a,d) Control; (b) Ti-Ca-C-O film (TiC0.5+10%CaO target, =0); (c,e) Ti-Si-Zr-O film (Ti5Si3+10%ZrO2 target, =0); (f) Ti-Ca-C-O-N film (TiC0.5+20%CaO target, =0.14).

16. Implantation study using bone defect model X-ray micrograph of titanium implant Substitution of calvarian bone defect by titanium implant Ti-Ca-P-C-O-N coating Ti plate without coating after 4 weeks Osteoblast cells were growing as a thin carpet on the coating surface and built together a morphological bone cell network.

17. 20 m (a) (b) 10 m Implantation study (a) Macrophages and (b) foreign body giant cell at the surface of Teflon coated with Ti-Ca-C-O film after subcutaneous implantation After 16 weeks of implantation in mice:  Close contact between the capsule and the film surface  Inflammatory reaction as on the control Population of cells: Macrophages – 400-1600 cells/mm2  Foreign body giant cells - low density (1-3% of cells)  Few neutrophils  No lympocytes

18. Coating Characteristics • Reduced Young’s modulus– 170-270 GPa {TiN-440GPa, TiC-480GPa, SiC-450 GPa, Al2O3-390 GPa, stainless steel – 200 GPa, Ti-120GPa} • High adhesion strength up to 50 N • High percentage of elastic recovery up to 75% (Hard elastic materials!) • Low coefficient of friction down to 0.12-0.22 • Low wear rate – 10-6 - 10-7 mm3/Nm • Low roughness Rrms=0.13-1.5 nm • High hardness – 30-40 GPa • High resistance to plastic deformation up to 0.9 GPa which is described by an H3/E2 ratio - a measure of “wear resistance”{The bulk ceramics (TiN, TiO2, SiO2 ZrO2 and SiC) are generally characterized by the H3/E2 parameters below 0.2 GPa} • High H/E ratio (long elastic strain to failure) as an indicator of coating durability and wear resistance • Negative surface charge at pH=7 • Biocompatibility • Low level of cytotoxicity • Inflammatory reactions as on the control

19. Moscow State Institute of Steel and Alloys, Leninsky pr. 4, Moscow119049, Russia Fax: (095)-236-5298, E-mail: shtansky@shs.misis.ru APPLICATION Ti medical nets with Ti-Ca-P-C-O-N coatings for implant fixation Dental implants with Ti-Ca-C-O-N coatings Chemical and biological safety tests of implants with coatings are under way

20. CONCLUSION Combination of excellent physical and mechanical properties with biocompatibility and non-toxicity makes Ti-Ca-C-O-(N), Ti-Zr-C-O-(N), Ti-Ca-P-C-O-(N) and Ti-Si-Zr-O-(N) films promising candidates as tribological coatings for load-bearing medical applications