Development of Bio-implant materials by Plasma-Spray Coating of Apatite and Their Evaluation

为了制备替代性人工骨材料，作者尝试在金属材料表面等离子涂层氢化磷灰石涂层。然而，等离子喷射层是如此疏松，以至于体液穿透到衬底并攻击它们。此外，由于极高的温度约为2,000℃，氢磷灰石层很容易分解，与基材失去接触。针对这些问题，作者研制了等离子喷涂氢磷灰石涂层材料。(1)H_3PO_4与Ca(OH)_2反应不能生成氢磷灰石，但老化和热处理促进了氢磷灰石的形成。(2)等离子喷涂形成了不含氢磷灰石的涂层。控制粉末半径有利于氢磷灰石的形成。(3)等离子喷涂的氢磷灰石为非晶态，经3h和800℃热处理后结晶。(4)对氢磷灰石涂层纯钛、工业钛棒和SUS316不锈钢在3.5%的氯化钠溶液中进行了腐蚀试验。氢磷灰石涂层只对纯钛有改善作用。这可能是由于氢磷灰石层与基材之间的结合紧密所致。研究还发现，热扩散处理改善了它们的连接。

In order to fabricate substitute artificial bone materials, the author tried plasma-coating of hydroapatite layer on metallic materials. However, the plasma-sprayed layers are so porous that body liquid penetrates to the substrates and attacks them. Moreover, because of extremely high temperature of ca.2,000℃, hydroapatite layer may easily decomposes and lose contact to the substrates. The author solved these problems and developed the plasma-sprayed hydroapatite coating materials. (1)The reaction of H3PO4 and Ca(OH)2 could not give hydroapatile but aging and heat-treatment promoted change into hydroapatite. (2)Plasma-spraying of, hydroapatite formed the coating layer without hydroapatite. However, controlling of the powder radius improved formation of hydroapatite. (3)Plasma-sprayed hydroapatite was amorphous, but crystallized by 3 hour and 800℃ heat-treatment. (4)Corrosion test of the hydroapatite-coated pure titanium, commercial Ti rod and SUS316 stainless steel was performed in 3.5%NaCl solution. Only the pure titanium was improved by hydroapatite coating. This is probably because joint between the hydroapatite layer and the substrate was tight. It was also found that the heat diffusion treatment improved their jointing.