| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1996: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1995: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Research Abstract |
The purpose of this work was to use ion-beam sputter deposition and ion-beam-assisted sputter deposition techniques for production of HAp coated implants. The calcium-phosphate compounds which stoichiometrically differ from HAp, are unstable in water, in PBS (phosphate-buffered saline) solutions, and in the human body. This is also in agreement with some of our experiments. This instability appears in two ways, either the films dissolve and disappear, or absorb the (OH-) and change to a more stable form. In the second case, if the TCP-coated device is inserted in a Ca-contained environment like PBS+, the film surface changes extensively and under certain conditions, the coating grows thicker. Using ion-beam-assisted sputter deposition method the adhesion of hydroxy apatite thin films has improved significantly, and increased to a level comparable to Ti and Al oxide thin films. In several cases, the Ca/P atomic ratios were almost similar to that of the theoretical value (1.67). Other components of the HAp, and TCP (O and H) deviated from the stoichiometric values, owing to absorbing the H20 vapor. The relative concentration of Ca, and P were affected by assisting-beam current density. The behavior of these films in water contained environment was different. The films which were stoichiometric or near-stoichiometric were more stable than non-stoichiometric films and they were not affected by accelerated aging in elevated temperature environment of saline water and PBS.
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