Modification of titanium by ion implantation of calcium and/or phosphorus

Pretreatment of titanium by implantation of P and Ca is of interest in orde r to improve the quality of hydroxyapatite coatings used to enhance its bio compatibility. A near surface implantation of high doses of calcium results in an oxidation of the modified layer and the formation of CaO. By post-im plantation annealing also Ca4Ti3O10 is formed. For deeper calcium implantat ions, precipitation of the metastable hexagonal modification of calcium has been observed instead of the cubic equilibrium phase. By high dose implant ation of phosphorus, the implanted layer becomes partly amorphized. This hi nders the reaction with oxygen during implantation and room temperature agi ng. The thickness of the surface oxide corresponds to the native oxide laye r. For high dose double implantation with both elements, due to the strong swelling effect and the incorporation of oxygen, the second implant is shif ted to the surface, if the energies are chosen so that the profiles should be overlapping by implantation into pure titanium. No indication for compou nd formation besides calcium oxide has been found as a result of the implan tation. (C) 1999 Elsevier Science S.A. All rights reserved.