Formation of a Layer between Hydroxyapatite and Titanium Substrate Heated by Argon Thermal Plasma.

In applying an inductively coupled thermal plasma of argon to spray of hydroxyapatite (HAp) on titanium substrate, a part of HAp powders reacted with the substrate to form a layer, which could not be identified with any of JCPDS. In order to eliminate any effects due to the spraying from determination of the substrate temperature at which the layer was formed, fine HAp powders on the substrate were heated by the plasma. The temperature dropped from 1123 K to 1013 K, when the plasma working gas of argon was added with hydrogen.