title: [Laser surface modification of medical titanium].
abstract: OBJECTIVE
  Titanium, by far one of the oldest materials in medical implants used for hard tissue replacement and rehabilitation, was used widely as implant material. The objective of the present study was to fabricate the TiN modified layer on the surface of medical pure titanium and improve its surface properties. Thus the wear resistance, biocompatibility and antisepsis were improved.
  
  
  METHODS
  A continuous-wave 2 kW Nd: YAG laser was used to irradiate the sample in the environment of N2 with concentration of 99.995%. Titanium nitride surface coatings had been extensively used as corrosion resistant and biocompatible layers on titanium and its alloys. The microstructure and composition of the laser nitrided coating were studied by scanning electron microscopy and X-ray diffraction. Microhardness of the modified sample was also analyzed by micro-hardmeter.
  
  
  RESULTS
  TiN modified layer with the thickness of about 400 microm was obtained. TiN distributed gradually from surface to the substrate. There was a good metallurgical bonding between the nitrided layer and the substrate. The hardness of the modified layer was reduced from the surface to the inside.
  
  
  CONCLUSIONS
  With optimum process parameters, a compact laser modified gradient coating reinforced with fine TiN was achieved on the surface of medical titanium.
authors.affiliation: Department of Dental Materials, School of Stomatology, China Medical University, Shenyang 110002, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Song
authors.initials: S
authors.lastname: Zhang
authors.forename: De-Song
authors.initials: DS
authors.lastname: Zhan
authors.forename: Jin-Ling
authors.initials: JL
authors.lastname: Hu
mesh_terms: D001672:Biocompatible Materials; D003343:Corrosion; D007834:Lasers; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D019736:Prostheses and Implants; D013499:Surface Properties; D014025:Titanium; D014961:X-Ray Diffraction
chemical_list: D001672:Biocompatible Materials; C041500:titanium nitride; D014025:Titanium