Advantages of HydroxyapatiteThe beneficial biocompatible properties of hydroxyapatite are well documented. It is rapidly integrated into the human body, while at the same time the body is none the wiser as to the invasion by a foreign body, albeit a friendly invasion. Perhaps its most interesting property is that hydroxyapatite will bond to bone forming indistinguishable unions. di羟基磷灰石的悲伤然而，机械性能（特别是疲劳性能）意味着不能以批量形式用于骨质轴承应用，例如骨科。 Hydroxyapatite CoatingsCoatings of hydroxyapatite have good potential as they can exploit the biocompatible and bone bonding properties of the ceramic, while utilising the mechanical properties of substrates such as Ti6Al4V and other biocompatible alloys. While the metallic materials have the required mechanical properties, they benefit from the hydroxyapatite which provides an osteophilic surface for bone to bond to, anchoring the implant and transferring load to the skeleton, helping to combat bone atrophy. Coating Techniques下表中总结了一些尝试的技术。
|
浸涂层 |
0.05-0.5mm |
便宜 涂料迅速施加 可以覆盖复杂的基材 |
需要高烧结温度 Thermal expansion不匹配 |
溅射涂层 |
0.02-1μm |
平面基材上的均匀涂层厚度 |
Line of sight technique 昂贵的 Time consuming CAnnot coat complex substrates Produces amorphous coatings |
脉冲激光沉积 |
0.05- 5μm |
As for sputter coating |
As for sputter coating |
热压和热等坐骨 |
0.2-2.0mm |
产生密集的涂料 |
惠普不能覆盖复杂的底物 需要高温 热膨胀不匹配 Elastic property differences 昂贵的 Removal/Interaction封装材料 |
Electrophoretic Deposition |
0.1-2.0mm |
Uniform coating thickness 快速沉积速率 可以覆盖复杂的基材 |
difficult to produce crack-free coatings 需要高烧结温度 |
Thermal Spraying |
30-200μm |
高沉积率
|
Line of sight technique High temperatures induce decomposition Rapid cooling produces amorphous coatings |
Sol-Gel |
<1μm |
可以覆盖复杂的形状 Low processing temperatures Relatively cheap as coatings are very thin |
Some processes require controlled atmosphere processing 昂贵的raw materials |
Information in the table above has been sourced from various scientific publications. Some of the coating techniques have been purely experimental. 血浆喷涂羟基磷灰石涂料在上面概述的技术中，特别是热喷涂，血浆喷涂是产生羟基磷灰石涂层的唯一商业上接受的方法。 尽管血浆喷涂是一个充分了解的过程，但对变量的控制非常复杂。处理变量的小变化可以极大地影响最终涂层的特性。 在羟基磷灰石涂层的情况下，由于其热不稳定性，这种类型的问题可能会加剧。诸如粉末原料等事物的变化可能会产生可溶性涂层。原因是羟基磷灰石遇到的高加工温度会诱导某些分解磷酸钙化合物。 Clinical BehaviourPlasma sprayed hydroxyapatite coated implants have become widely used over the last twenty years, with several companies manufacturing devices for orthopaedic and dental applications. 通常，植入物的性能很好。实际上，当从患者（有时搞砸）与周围骨骼分离时，骨/涂料界面失败了。这表明骨骼和涂层之间的键比金属替代和羟基磷灰石涂层之间的键形成了更强的键。 |