Hydroxyapatite and Other Biomedical Coatings by Electrophoretic Deposition - Biological and Biomedical Coatings: Processing and Characterization - page 127

Processing parameters
• Applied voltage and deposition time
• Electrical conductivity of substrate
• Surface area of substrate
• Electrode separation
The DLVO and other theories assume that the surface charge of particles is isotropic.
While this is the case in cubic and amorphous materials, this is not so with other crystal-
line materials. Hence, the present work introduces a new consideration in the form of the
(1) effect of anisotropic surface charge on the suspension and electrophoretic deposition of
powders and (2) effect of surface charge saturation. These considerations were explained
briefly in the text but they were clarified more fully in graphical form.
A large range of published studies of the electrophoretic deposition of hydroxyapatite
has been presented. This coverage was categorized according to the following topics:
• Electrophoretic deposition
• Ceramic-metal interfaces
• Metallic substrates
• Interfacial stresses and adhesion
• Hydroxyapatite-polymer composite coatings
• Biomedical considerations
Probably the most encouraging information is embodied in the recent work on hydroxy-
apatite-chitosan composites, where the polymer phase provides both bonding between
the ceramic particles and to the metallic substrate, thereby obviating the need for high-
temperature densification and fixation to the substrate, which often is associated with
intractable shortcomings in the resultant materials.
The present work has been complemented by extensive tabulated data that summarize
the materials, processing parameters, and outcomes of published work in the following
areas:
• Electrophoretic deposition of alumina, zirconia, and other oxides in aqueous and
organic media
• Electrophoretic deposition of zirconia on insulating substrates
• Electrophoretic deposition of hydroxyapatite in organic media
References
1. L. Hench, Bioceramics, J. Am. Ceram. Soc. , 81 [7] 1705-28 (1998).
2. D. Manno, G. Micocci, R. Rella, A. Serra, A. Taurino, and A. Tepore, Titanium Oxide Thin Films
for NH 3 Monitoring: Structural and Physical Characterizations, J. Appl. Phys. , 82 [1] 54-59
(1997).