EVALUATION OF MECHANICAL CHARACTERISTICS OF BIO-CERAMIC FUNCTIONALLY GRADIENT COATING IMPLANT

本研究的目的是从残余应力和附着强度的角度评价生物陶瓷功能梯度涂层植入体的力学特性。采用常压等离子喷涂工艺制备了生物陶瓷功能梯度涂层。随后在钛基体表面涂覆四层羟基磷灰石与钛的体积混合比逐渐变化的膜层。每层厚度为20μm。比较了功能梯度涂层与羟基磷灰石涂层的力学特性。(1)采用x射线衍射法测量涂层中产生的残余应力。采用mo - k - α的特征x射线。本实验选择羟基磷灰石的（002）晶格面。以下结果得到确认。(a)功能梯度涂层存在224MPa的残余压应力。(b)仅羟基磷灰石涂层试样的涂层层残余压应力为295MPa。(c)采用功能梯度涂层后，生物陶瓷涂层试样涂层层的残余压应力减小。(2)采用三点弯曲法对涂层的附着力进行评价。对60×10×2mm^3弯曲试样进行羟基磷灰石和钛包覆。三点弯曲跨度为42mm。试件加载至最大挠度为3mm。测量了涂层分层面积的大小。以下结果得到确认。(a)功能梯度涂层和仅羟基磷灰石涂层试样的分层面积分别为4.6mm^2和10.9mm^2。(b)功能梯度涂层试样与羟基磷灰石涂层试样相比，涂层的粘附强度更强。少

The purpose of research is to evaluate the mechanical characteristics of a bio-ceramic functionally gradient coating implant from a point of view of residual stress and adhesion strength. The bio-ceramic functionally gradient coating specimen was made using atmospheric plasma-spray processing. Four layers in which the volume mixture ratio of the hydroxyapatite and the titanium gradually change were subsequently coated on the surface of titanium substrate. The thickness of each layer was 20μm. The mechanical characteristics of the functionally gradient coating specimen were compared with those of the specimen coated only with hydroxyapatite.(1) The residual stress generated in the coating layer was measured using X-ray diffraction method. The characteristic X-ray of Mo-Kα was used. The (002) lattice plane of hydroxyapatite was selected in this experiment. The following results were confirmed.(a) Compressive residual stress of 224MPa existed in the functionally gradient coating layer.(b) … More Compressive residual stress of 295MPa in the coating layer of the specimen coated only with hydroxyapatite was measured.(c) The compressive residual stress in the coating layer of the bio-ceramic coating specimen decrease when using a functionally gradient coating.(2) The adhesion strength of the coating layer was evaluated using three-point bending method. The bending specimen of 60×10×2mm^3 was coated with hydroxyapatite and titanium in the same manner as state above. The span for three-point bending was 42mm. The specimen was loaded until the maximum deflection became 3mm. The size of delaminated area of coating layer was measured. The following results were confirmed.(a) The delaminated areas of the functionally gradient coating specimen and the specimen coated only with hydroxyapatite were 4.6mm^2 and 10.9mm^2, respectively.(b) The functionally gradient coating specimen is superior in the adhesion strength of coating layer in comparison with the specimen coated only with hydroxyapatite. Less