Application of new zirconia/alumina composite ceramics to bearing surfaces of artificial joint prostheses

研究了Ce-TZP/Al_2O_3纳米复合材料的生物相容性、相稳定性和磨损性能。生物相容性测试：将CeTZP/Al_2O_3和氧化铝圆柱体标本植入雄性Wistar大鼠椎旁肌内。CeTZP/Al_2O_3的生物相容性与氧化铝基本相同。两种陶瓷均在1周时出现中度软组织反应，此后巨噬细胞和淋巴细胞逐渐减少。24周时，两种陶瓷均形成稳定的囊膜，有少量纤维细胞，几乎没有炎细胞。CeTZP/Al_2O_3纳米复合材料的膜厚与Al_2O_2无显著差异。老化试验：将CeTZP/Al_2O_3和YTZP在不同老化条件下(兔胫骨、62℃生理盐水或高压灭菌器)保存。用薄膜X射线衍射仪对时效处理后的样品表面进行了观察，并测定了单斜晶相的体积分数。虽然Y-TZP在体外有明显的相变，但在所有条件下Ce-TZP/Al_2O_3的单斜率几乎没有变化。磨损试验：在水润滑(接触压力为11.3 Mpa)下，氧化铝销钉的平均磨损率为2.12±0.37×10~(-7)mm~(-3)/Nm，Ce-TZP/Al_2O_3为0.55±0.04×10~(-7)mm~(-3)/Nm。在30%的血清润滑下(接触压力为50 Mpa)，未老化的Ce-TZP/Al_2O_3、Y-TZP和氧化铝试件的磨损率无显著差异。Y-TZP陶瓷的磨损率明显高于Ce-TZP/Al_2O_3非晶复合材料的磨损率

We have investigated the biocompatibitity, phase stability and wear properties of Ce-TZP/Al_2O_3 nanocomposite1. Biocompatibility test: We implanted cylinder specimens of CeTZP/Al_2O_3 and Alumina into paraspinal muscles of male Wistar rats. The biocompatibility of CeTZP/Al_2O_3 was almost the same as that of Alumina. For both of ceramics, moderate soft tissue responses were noted at 1 week, and thereafter macrophages and lymphocytes decreased gradually. At 24 weeks, stable encapsulating membranes with some fibrocytes and almost no inflammatory cells were observed for both of ceramics. There were no significant differences of the membrane thickness between CeTZP/ Al_2O_3 nanocomposite and Alumina2. Aging test: Test specimens of CeTZP/AI2O3 and YTZP were kept under various aging conditions (rabbit tibiae, 62°C saline or autoclave). The surface of the specimens was examined after the aging treatments by thin-film X-ray diffraction, and the volumetric fraction of the monoclinic phase was determined. Although Y-TZP showed remarkable phase transformation under in vitro conditions, almost no change m the monoclinic rate was observed for Ce-TZP/Al_2O_3 under all conditions3. Wear test : In water lubrication ( contact pressure ;11.3MPa), the average wear rate of the pin was 2.12±0.37× 10^<-7>mm^3/Nm for Alumina and 0.55±0.04× 10^<-7>mm^3/Nm for Ce-TZP/Al_2O_3. In 30 vol% serum lubrication ( contact pressure ;50 Mpa), there were no remarkable differences in the wear rates of Ce-TZP/Al_2O_3 nonocomposite, Y-TZP and alumina specimens without aging (36 h autoclave). However, the wear rates of Y-TZP with aging were much higher than that of Ce-TZP/Al_2O_3 nonocomposite with agingThe present results suggest that this ceramic is very promising as a bearing component in artificial joint