氧化锆陶瓷注射成形工艺研究

【作者】 聂妍；

【导师】 李益民；

【作者基本信息】 中南大学 ， 材料学， 2004， 硕士

【摘要】 陶瓷注射成形技术(CIM)是一项很有前途的陶瓷成形技术。本文探讨了如何运用注射成形技术制备性能良好的氧化钇部分稳定氧化锆陶瓷制品。 注射成形氧化锆采用油-石蜡基粘结剂体系，粉末装载量为50vol％。实验所用的粘结剂体系能够满足氧化锆粉末(平均粒度为0.8μm)对CIM粘结剂的要求。粘结剂对陶瓷粉末的润湿性能好，且喂料的流变性能良好。粘结剂可以采用分步脱脂法脱除。 对于样品的注射成形来说，注射熔体的温度和注射压力为喂料注射过程的关键工艺参数。实验中喂料的最佳注射参数为：注射温度155±5℃，注射压力为系统总压力的60～70％，其它参数为：模温55±5℃，保压压力为系统总压力的55％左右。 注射坯的溶剂脱脂在恒温水浴装置中进行。粉末的形状和粒度、溶剂种类、生坯的几何形状和脱脂温度均对溶剂脱脂效果有明显的影响。通过对粘结剂和喂料的热分解行为的探讨，试图得到理想的脱脂工艺条件和曲线，使粘结剂完全脱除且脱脂坯无缺陷和变形。经过反复摸索，分别得到各个样品的最佳脱脂工艺曲线。 经过反复实验，得到了较理想的、无烧结缺陷的烧结工艺。生坯的烧结在硅钼棒高温电炉中进行，采用空气气氛。实验确定了烧结的温度-时间曲线，烧结后样品达到致密化，且无晶粒过大。 目前限制CIM技术发展的主要因素是对产品缺陷的控制，而样品的缺陷在每个工艺阶段都有可能出现。本文探讨了样品在注射成形的注射、脱脂和烧结各个阶段可能产生的缺陷及其形成机理。注射阶段产生的最主要缺陷为孔洞和裂纹，须通过对注射压力和温度的调节来消除这些缺陷的产生。脱脂和烧结阶段缺陷的形成机理更为复杂，且很难区分。然而，通过观察可发现，脱脂和烧结阶段出现的缺陷很多是在注射阶段形成的。 烧结后制品的力学性能和其他性能优于目前市场同类氧化锆材料的性能。样品形状和尺寸对制品性能影响较大。与传统P／M法生产的陶瓷制品相比，陶瓷中南大学硕士学位论文摘要品形状和尺寸对制品性能影响较大。与传统P胭法生产的陶瓷制品相比，陶瓷注射成形技术的优势体现在小体积、形状复杂制品的生产制备方面，对于大型制品的制备研究探索还需进一步加强。最后，本文讨论了样品中的缺陷对强度的影响，通过计算得出含裂纹材料的强度曲线图，并与实验结果进行了比较验证。更多还原

【Abstract】 Injection molding of ceramics (CIM) is considered as a promising shaping technique. An investigation was started to test whether injection molding of yttrium oxide stabilized tetragonal zirconia can result in products with good mechanical properties. The results have shown as the following:An oil-wax-based binder system with 50vol% zirconia was injection-molded. The binder system can meet the demand of the zirconia powder (the average size of 0.8lμm ) selected in the experiment. The binder has good wetting qualities with the powder and the feedstock has favorable rheological behavior. The binder can be removed by the step-by-step debinding.For the samples injected, the molding temperature and molding pressure are the key process parameters of the molding process of feedstock. The optimal molding parameters for the feedstock are as following: temperature for molding 155 ±5 ℃, molding pressure 60-70%. Other parameters are as following: temperature of mould 55±5℃, holding pressure about 55%.The next step, solvent debinding was done in water bath equipment. The particle shape and its size, character of solvent, shape of the green parts and temperature has strong influence to the solvent debinding results. The thermal decomposition behaviors of binders and feedstock are also studied to find process conditions during which the binder can be completely removed from the products without damage or dimensional change. After investigating carefully, the best debinding process of different samples have been obtained respectively.After that, by series of experiments, the author of the dissertation has got the optimal sintering process. The sintering of the green products was done in a superkanthal furnace with air atmosphere. A temperature-time profile was determined in which full densification occurred, but no excessive grain growth took place.The main limitation of CIM is the control of defects, however, these can arise in any of the processing stages. The causes of the defects in injection-moulded ceramic samples during injecting, debinding and sintering process were investigated. The mostAbstractsignificant defects that occur during injection molding are voids and cracks, modulated molding pressure and temperature have been used to diminish voids formation. The causes of defects during debinding and sintering are far more complicated and difficult to isolate. However, it has been observed that the defects, which develop during debinding and sintering, may originate from the injection stage. The mechanical properties and other properties of the sintered parts produced compare favorably to those of commercially available zirconia materials. It appears very dependent on the shape and size of the samples. Comparing with the traditional method of P/M of manufacturing ceramics, the advantage of CIM is the fabrication of complex shapes for small section components and the problems of preparing large components continue to be explored. Finally, the effects of defects on the strength of samples were investigated. The strength diagram of materials with crack was calculated and was also compared with experimental results.更多还原