ELECTROPHORETIC NANO-HYDROXYAPATITE COATING FOR ADHESION

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Poor adhesion is the single most severe problem related to the long term viability of implantable hydroxyapatite coatings. An innovative room temperature electrophoretic process is proposed to fabricate nanostructured hydroxyapatite ("n"-HAP) coatings, eliminating problems related to amorphous phase formation and delamination. To date, only micron-sized hydroxyapatite materials have been deposited using electrophoresis. The n-HAP coating will exhibit increased toughness, bond strength, and a high degree of crystallinity. The nature of the bond is metallurgical, resulting in dramatically improved bond strength when compared to mechanical bonds obtained in thermal spray coatings. Electrophoresis also enables multicomponent codeposition. This program consists of (1) synthesizing n-HAP particles, (2) depositing the n-HAP coating, and (3) coating evaluation. while the n-HAP is expected to yield a several4old increase in bond strength, a calcium phosphate cement (CPC) additive will be cc-deposited with the n-HAP to further increase bond strength. A dense graded TiO2 bond coat will be introduced (a few microns thick) between the n-HAP and the titanium substrate in the deposition process, so that body fluids will have no opportunity to attack and degrade the titanium. Inframat is collaborating with Dr. Antoni Tomsia of the Lawrence Berkeley National Lab to evaluate the nanostructured coatings. PROPOSED COMMERCIAL APPLICATIONS: Potential commercial applications include advanced coated implants for hips, knees, and other prostheses in humans and animals. In the US alone,the annual number of hip and knee operations using HAP coated implants is estimated to already produce an annual revenue of $3 billion. With the increasing age of the larger population, the estimated demand for implants will rise significantly in the near future. A comparable European market doubles the potential revenue.