title: Carbon plasma immersion ion implantation of nickel-titanium shape memory alloys.
abstract: Nickel-titanium (NiTi) shape memory alloys possess super-elasticity in addition to the well-known shape memory effect and are potentially suitable for orthopedic implants. However, a critical concern is the release of harmful Ni ions from the implants into the living tissues. We propose to enhance the corrosion resistance and other surface and biological properties of NiTi using carbon plasma immersion ion implantation and deposition (PIII&D). Our corrosion and simulated body fluid tests indicate that either an ion-mixed amorphous carbon coating fabricated by PIII&D or direct carbon PIII can drastically improve the corrosion resistance and block the out-diffusion of Ni from the materials. Our tribological tests show that the treated surfaces are mechanically more superior and cytotoxicity tests reveal that both sets of plasma-treated samples favor adhesion and proliferation of osteoblasts.
authors.affiliation: Department of Physics and Materials Science, City University of Hong Kong, Kowloon, Hong Kong.
authors.forename: R W Y
authors.initials: RW
authors.lastname: Poon
authors.forename: K W K
authors.initials: KW
authors.lastname: Yeung
authors.forename: X Y
authors.initials: XY
authors.lastname: Liu
authors.forename: P K
authors.initials: PK
authors.lastname: Chu
authors.forename: C Y
authors.initials: CY
authors.lastname: Chung
authors.forename: W W
authors.initials: WW
authors.lastname: Lu
authors.forename: K M C
authors.initials: KM
authors.lastname: Cheung
authors.forename: D
authors.initials: D
authors.lastname: Chan
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D040761:Biomimetic Materials / Q000737:chemistry; D001826:Body Fluids / Q000737:chemistry*; D002244:Carbon / Q000032:analysis / Q000737:chemistry*; D002448:Cell Adhesion / Q000502:physiology; D049109:Cell Proliferation; D048429:Cell Size; D002478:Cells, Cultured; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D003343:Corrosion; D004548:Elasticity; D004563:Electrochemistry / Q000379:methods*; D006244:Hardness; D006358:Hot Temperature; D007477:Ions; D008422:Materials Testing; D051379:Mice; D009532:Nickel / Q000032:analysis / Q000737:chemistry*; D010006:Osteoblasts / Q000166:cytology* / Q000502:physiology*; D013499:Surface Properties; D014025:Titanium / Q000032:analysis / Q000737:chemistry*
chemical_list: D020099:Coated Materials, Biocompatible; D007477:Ions; C040654:titanium nickelide; D002244:Carbon; D009532:Nickel; D014025:Titanium