AVS 52nd International Symposium
    Biomaterial Interfaces Monday Sessions
       Session BI-MoP

Paper BI-MoP7
Formation of Highly Oriented Hydroxyapatite Coating by rf Thermal Plasma Spraying

Monday, October 31, 2005, 5:00 pm, Room Exhibit Hall C&D

Session: Biomaterial Interfaces Poster Session
Presenter: M. Inagaki, National Institute of Advanced Industrial Science and Technology (AIST), Japan
Authors: M. Inagaki, National Institute of Advanced Industrial Science and Technology (AIST), Japan
Y. Yokogawa, National Institute of Advanced Industrial Science and Technology (AIST), Japan
T. Kameyama, National Institute of Advanced Industrial Science and Technology (AIST), Japan
Correspondent: Click to Email
Hydroxyapatite (Ca@sub 10@[PO@sub 4@] @sub 6@ [OH] @sub 2@; HA) has been used for medical applications to promote the osteoconductivity of implanted materials.@footnote 1@ The HA crystal has hexagonal structure with space group of P63/m and has anisotropic properties of matter with respect to the crystallographic axis due to crystal structure of itself. Moreover, the HA crystal has two major surfaces i.e. (100) surface (a-surface) and (001) surface (c-surface) with different properties, such as protein absorption@footnote 2@ and dissolution behavior.@footnote 3@ In this study, highly oriented hydroxyapatite (HA) coatings were successfully obtained on titanium (Ti) substrates through a radio-frequency thermal plasma spraying method. XRD patterns showed that the HA coating layer had an apatite structure with (00l) preferred orientation vertical to the coating's surface. TEM observation showed that 200-800 nm-width prismatic crystals were formed in HA splats and the longitudinal axis of such prismatic crystals oriented vertical to the coating's surface. TEM images also indicate that the interface between prismatic crystals became compacted. SAD pattern show that the longitudinal axis of prismatic crystals corresponds to the (001) axis of HA. Protein absorption behavior of such a crystal oriented surface was also studied. @FootnoteText@ @footnote 1@ L. L. Hench, J. Am. Ceram. Soc., 81, (1998) 1705.@footnote 2@ T. Kawasaki, J. Chromatogr., 544, (1991) 147.@footnote 3@ H. Aoki, Surface Science, 10, (1989) 96.