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

目前已有研究利用羟基磷灰石（HAP）和部分稳定氧化锆（PSZ）的粉末混合物制备出与骨组织有亲和力的人工骨材料，具有较高的机械强度和断裂韧性，但效果不理想。本研究采用干冲击共混法对较大粒径的球形细小HAP颗粒（Dm=9.32mum）与较小粒径的球形细小PSZ颗粒（Dm=0.12mum）进行表面涂覆。利用NHS-0型杂交系统（Nara Machinery Co.）将球形HAP细颗粒与PSZ细颗粒混合。球形HAP细颗粒表面完全包覆了PSZ细颗粒。100% HAP的烧结体断裂韧性为1.1MPam^<0.5>，而HAP/PSZ重量比为10/2、10/5和10/10的烧结体断裂韧性分别为1.8、2.8 MPam^<0.5>。断裂韧性值2.8 MPam^<0.5>接近人工骨所需的3.0 MPam^<0.5>。通过电镜观察发现，很少观察到彼此直接连接的细小HAP粒子。复合细颗粒的烧结体包括三维连续网状的PSZ相，其中分散着球形的HAP细颗粒。由此可以理解，PSZ的断裂韧性仍然存在于复合细颗粒烧结体中。x射线衍射结果表明，HAP/PSZ比值分别为10/2、10/5和10/10的烧结体由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.