Influence of Assist Laser Irradiation Timing on Quality of HAp Coating in LALA Method

In order to create the implant material which has high biocompatibility, a new hydroxyapatite (HAp) coating method, the laser-assisted laser ablation (LALA) method, has been developed. In this method, control of assist laser irradiation timing (delay time after an ablation laser irradiation) is very important for the quality of a HAp coating layer. We studied the influence of the timing on adhesion strength , crystallinity and Ca/P value of the HAp coating. Quality of the HAp coating layer obtained at a delay time of a few microseconds was extremely high. On the other hand, the layer obtained over 10 microseconds had more amorphous component and contained other calcium phosphate compounds from HAp. Using the present method, we succeeded in fabricating thin film (≦1 μm) of HAp with high crystallinity.