Improvement of Mechanical Properties of Artificial Bone Material Composed of Hydroxyapatite and Zirconia

利用羟基磷灰石(HAP)和部分稳定氧化锆(PSZ)的粉末混合物开发出一种与骨组织具有亲和力、具有高机械强度和断裂韧性的人工骨材料，迄今已进行了一些研究，但效果不佳。本研究采用干冲击共混法对较大尺寸的球形微细HAP颗粒(Dm=9.32um)与较小尺寸的PSZ微细颗粒(Dm=0.12um)进行表面包覆。用NHS-0型杂化系统(奈良机械公司)将球形细HAP颗粒与细PSZ颗粒混合。球形细小的HAP粒子表面完全被PSZ微球包裹。HAP/PSZ质量比为10/2、10/5和10/10的烧结体的断裂韧性分别为1.8和2.8MPam；断裂韧性值为2.8MPAM^；0.5；接近人工骨所需的3.0MPAM^；0.5；通过电子显微镜观察发现，很少观察到相互直接相连的细小HAP颗粒。复合细颗粒的烧结体由三维的、连续网状的PSZ相组成，其中分散着球形的细HAP颗粒。由此可见，PSZ的断裂韧性仍然存在于复合细颗粒的烧结体中。X射线衍射仪结果表明，HAP/PSZ为10/2、10/5和10/10的烧结体仅由HAP和PSZ组成，说明HAP没有转化为磷酸三钙。

Several studies have been made using powder mixture of hydroxyapatite (HAP) and partially stabilized zirconia (PSZ) so far to develop an artificial bone material with affinity to bone tissue and exhibiting high mechanical strength and fracture toughness, but with less satisfactory results. In this study surface coating of relatively large-sized spherical fine HAP particles (Dm=9.32mum) with small-sized fine PSZ particles (Dm=0.12mum) by the dry impact blending method conducted. The spherical fine HAP particles were mixed with fine PSZ particles using an NHS-0 Type Hybridization System (Nara Machinery Co.). The surface of the spherical fine HAP particles were completely coated with the fine PSZ paricles. The fracture toughness of the sintered body consisting of 100% HAP was 1.1MPam^<0.5>, while those with the HAP/PSZ weight ratios of 10/2 and 10/5, and 10/10 are 1.8 and 2.8 MPam^<0.5>, respectively. Fracture toughness values of 2.8 MPam^<0.5> is close to the 3.0 MPam^<0.5> required for the artificial bone. By electron microscopic observation, it was revealed that fine HAP particles directly connected to each other are seldom observed. The sintered body of the composite fine particles comprises a three-dimensional, continuously reticulate phase of PSZ in which spherical fine HAP particles are scattered. It could be understand from this observation fracture toughness of PSZ still remains in the sintered body of the composite fine particles. The result of the X-ray diffractometry indicates that the sintered bodies with the HAP/PSZ ratios of 10/2,10/5 and 10/10 consist of HAP and PSZ alone, showing that HAP is not transformed to tricalcium phosphate.