New method for hydroxyapatite coating of titanium by the hydrothermal hot isostatic pressing technique

Takamasa Onoki, Toshiyuki Hashida

Research output: Contribution to journalArticlepeer-review

48 Citations (Scopus)


A new hydrothermal method is proposed, which enables us to prepare thin hydroxyapatite (HA) ceramic coatings on Ti substrates with a curved surface at low temperatures. The method uses double layered capsules in order to produce a suitable hydrothermal condition; the inner capsule encapsulates the coating materials and a Ti substrate, and the outer capsule is subjected to isostatic pressing under the hydrothermal condition. In this study, it is demonstrated that a pure HA ceramic layer with the thickness of 50 μm could be coated to a Ti cylindrical rod at the low temperature as low as 135 °C under the confining pressure of 40 MPa. The HA coating layer had a porous microstructure with the relative density of approximately 60%. Pull-out tests were conducted to obtain an estimate for the adhesion properties of the HA coating prepared by the double capsule method. The shear strength obtained from the pull-out tests was in the range of 4.0-5.5 MPa. It was also shown that the crack propagation occurred within the HA coating layer, not along the HA/Ti interface in the pull-out tests. This observation suggests that the fracture property of the HA/Ti interface was close to or higher than that of the HA ceramics only. It is expected that the low temperature double capsule method may provide a useful method for producing bioactive HA ceramic coatings on curved prostheses surfaces.

Original languageEnglish
Pages (from-to)6801-6807
Number of pages7
JournalSurface and Coatings Technology
Issue number24
Publication statusPublished - 2006 Aug 1


  • Double capsule
  • Hydrothermal
  • Hydroxyapatite
  • Pull-out testing
  • Titanium

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry


Dive into the research topics of 'New method for hydroxyapatite coating of titanium by the hydrothermal hot isostatic pressing technique'. Together they form a unique fingerprint.

Cite this