【作者】 吴晨曦；

【导师】 陈晓明；

【作者基本信息】 武汉理工大学 ， 材料学， 2004， 硕士

【摘要】 氧化铝生物陶瓷具有硬度高、耐磨损、良好的生物相容性和化学稳定性等特点，是制作人工关节的优良材料，但其脆硬特性却给加工带来了很大的困难，限制了在临床上的广泛应用。本文以氧化铝陶瓷人工关节股骨头经济、高效的制备工艺和加工方法作为研究目标，以期为产业化创造条件。采用数控车削方法，从材料的制备成型、加工工艺、自动编程、加工性能及切削用量优化等方面进行实验分析和研究。 选择高纯超细α-Al₂O₃粉为原料，以MgO-ZrO₂（Y₂O3）为复合添加剂，采用氨水沉积包裹法配料，经脱水、烘干、煅烧处理，得到烧结活性良好的粉料。粉料经预模压后冷等静压成型，能得到均匀致密的陶瓷坯体。压制后的坯体经干燥和1150℃预烧，使之具备适宜的机加工强度，然后根据人工关节股骨头假体的尺寸设计图在数控车床上精密车削成型。成型后的坯体经1600℃保温2.5小时烧结，获得致密的烧结体，经研磨、抛光等后序工艺处理，最终能获得表面近似镜面光洁度并与股骨柄配合良好的氧化铝陶瓷股骨头。 在基于计算机辅助设计与制造软件Pro／Engineer的平台上，开发了面向指定机床的数控自动编程系统，实现了设计与加工一体化。首先，由CAD建模和生成制造模型，系统提取其特征信息，自动生成加工轨迹；然后应用仿真功能，在虚拟环境下仿真加工的过程与结果；最后经后置处理生成特定机床的数控代码，实现自动编程。利用CAD／CAM一体化技术，能检验产品的正确性，提高机床利用率。 分析了烧结工艺对氧化铝预烧坯体加工性能的影响。分别讨论了改变升降温速率、预烧温度和保温时间与坯体加工性能之间的关系；采用1150℃预烧，保温2小时，及分段控制升温速率的工艺，获得了适合机加工的坯体，能避免加工时的断裂、破碎或崩边。通过对1150℃预烧后的坯体进行加工实验，讨论了主轴转速、进给速度、背吃刀量等切削参数与加工成本之间的关系，并得出了以最低成本为目标的切削参数值。武汉理工大学硕士学位论文 上述研究表明:从材料的制备与加工工艺、数控编程方法、加工成本等因素考虑，氧化铝陶瓷人工关节股骨头的数控加工技术能适应产业化的要求。更多还原

【Abstract】 With high hardness, high abrasive resistance, good biocompatibility and chemistry stability and so on, alumina ceramic has been considered as an excellent material for making artificial joints. However, the extensive applications were limited due to its hard and brittle properties that brought great difficulties in manufacturing. In this paper, high efficiency and economic manufacturing means were studied for industrial production of the alumina ceramic femoral head prostheses. By the way of the numerical control machining, the optimization related to preparation, process, automatically programming and cutting parameter were studied.Firstly, high pure a-Al2O3 and MgO-ZrO2 (Y2O3) composite additives were mixed with the method of the ammonia precipitating-enwrapping. After dehydrating, drying and calcinating, the powder with good sintering activity was acquired. The ceramic green was shaped by pressing and cold isostatic pressure, then an uniform and compact ceramic green was produced. The ceramic green was pre-calcined at 1150 C to have proper strength for machining and then the femoral head prostheses on the basis of the required design drawing was shaped through precisely turning on the NC lathe. The shaped prostheses was sintered at 1600 C for 2.5 hours in an electrical furnace. Finally, the surface of the alumina femoral head was ground and polished, which made the surface reaching the degree of approximate mirror finish and matching the femoral stem well.Based on the Pro/Engineer-a software for Computer Aid Design and Manufacture the automatic programming system for the specific NC machine was developed, so the integration of design and machining can be realized. First of all, those features from CAD/CAM manufacturing model were chosen for generating machining track. Then the process and outcome were simulated on the screen. Finally the NC codes were generated after post process and the automatic programming was completed. NC Machine’s utilization ratio as well as yield was enhanced by this CAD/CAM integration technique.The relationships between the presintering process including the ratio of heating-up, presintering temperature and holding time to alumina and the machiningperformance of its presintered briquet were studied respectively. The alumina briquet was acquired which was presinetered at 1150 C, 2 hours holding time and heating-up curve with several heating-up ratios, and which could avoid rapture or breaking when machined. The machining experiment has been studied to the briquet presintered at 1150 C. The machining cost related to cutting parameters, such as shaft speed, feedrate and cutting depth has been discussed. Then the best cutting parameters have been obtained which led to the least cost.From above study, it would be concluded that the NC machining can meet the request of industrialization of femoral head prosthesis for alumina ceramic.更多还原