New materials for artificial joint -Development of hydroxyapatite containing glass coated titanium composite-

众所周知，羟基磷灰石（HA）是一种生物活性陶瓷，与机体环境具有良好的生物相容性，纯钛和具有足够机械强度的Ti-6Al-4V等钛合金是具有良好生物稳定性和亲和力的合适金属。近年来，羟基磷灰石涂层种植体被广泛应用于髋关节假体和牙体假体，其中羟基磷灰石层通过等离子喷涂、溅射、热压和激光沉积等方法涂覆在钛基表面。在这些技术中，等离子喷涂是商业产品中常用的一种方法。但在等离子体高温下，羟基磷灰石会发生热分解，导致化学成分和结构发生变化，厚度超过50 μ m的羟基磷灰石涂层表现为脆性陶瓷，容易剥落。此外，在拉伸载荷作用下，更多HA涂层与钛或Ti-6Al-4V基体的线性热膨胀系数差异较大，会导致疲劳失效。从这一角度来看，采用新制备的玻璃和传统的搪瓷工艺制备了含HA玻璃涂层钛复合材料（HA- g - ti复合材料），而无需使用等离子喷涂等高温工艺。该复合材料包括涂有含HA的玻璃层的基板，其中，所述层包括具有分散HA颗粒的连续玻璃相，并且表面制备为粗化状态。HA- g - ti复合材料由于HA和钛的机械强度而具有潜在的生物活性，是一种生物相容性的复合材料，尤其适用于种植体的应用。结果表明，不同HA浓度的含HA玻璃的物理性质适合于构成生物活性植入物的HA- g - ti复合材料，并能使含HA玻璃与基质之间具有良好的粘附性。少

It is well known that the hydroxyapatite (HA) is a bioactive ceramic having excellent biocompatibility with the body environment, and that pure titanium and titanium alloy such as Ti-6Al-4V with sufficient mechanical strength are suitable metals exhibiting good biological stability and affinity. In recent years, paticular attention has been drawn to the use of HA-coated implants for hip prostheses and a dental implants in which HA layr is coated on the surface of titanium substrate by plasma spraying, sputtering, hot pressing, and laser deposition, etc. Among these techniques, plasma spraying is a method commonly used in commercial products. However'there is a problem of change of chemical composition and structure due to the themal decomposition of HA under high temperature in plasma, and the HA coating layr with more than 50 mum in thickness behave like a brittle ceramic and leads to the peeling. Furthemore, the large difference in the linear thermal expansion coeffcient between the … More HA coating layr and the titanium or Ti-6Al-4V substrate can cause fatigue failure under tensile load.From the point of view, a HA containing glass coated titanium composite (HA-G-Ti composite) was developed with newly prepared glass and conventional enameling technique without using high temperatures such as plasma spraying. This composite consists of a substrate coated with a HA containing glass layr, wherein the layr comprises a continuous glass phase with dispersed HA particles and the surface is prepared in a roughened state. It has been found that the HA-G-Ti composite provides both bioactivity potential due to the HA and the mechanical strength of titanium, and the composites are useful for biocompatible composite materials which are especially suitable for implant applications. It is demonstrated that the physical properties of the HA containing glass with different concentration of HA are suitable to constitute the HA-G-Ti composite for bioactive implant and to make an excellent adhesion between the HA containing glass and the substrate. Less