抄録
This paper describes evaluation process of residual strengths of plasma-sprayed hydroxyapatite(HAp) coatings by Raman spectroscopy. Plasma-sprayed HAp coatings are widely used in the fields of medical implant in order to improve the biocompatibility of substrate alloys in vivo. The strength of the HAp coating is affected by complex factors. One of them is residual stresses that lead to cracking due to its positive value. The thickness of coatings limit methods of residual stress evaluations by using XRD etc and crystal phase is also changed during spraying, which disturb the accurate prediction of residual stress from macroscopic method. The authors then used Raman microscopy to observe residual stress distributions through the coatings. The peak value of Raman shift is moved in the case of plasma-sprayed one compared with bulk sintered one. Residual stress becomes lower in the edge of HAp coatings by cracking. In the cases of HAp coating and HAp+ Ti bond coat, residual stress became lower and no crack was observed. This result can explain the enhancement effect of bond coat on the strength of coatings.
