【作者】 王川；

【导师】 郑治祥；

【作者基本信息】 合肥工业大学 ， 材料学， 2004， 硕士

【摘要】 可切削微晶玻璃因其可用常规工具加工而倍受瞩目。在云母基可切削微晶玻璃中，云母结构中层面间的弱连接是导致材料强度低的主要原因。针对此问题，采用Ca²⁺替代部分K⁺可增强云母结构的结合力，提高云母晶体自身的强度；同时掺杂氧化锆来增强和增韧，可制得高强度可切削微晶玻璃。本研究对以钙云母为主相的可切削微晶玻璃的制备工艺、结构特点、增强增韧机理及力学性能等进行了初步的研究。 本论文探讨了CaO-MgO-Al₂O₃-SiO₂-F系氟硅酸盐微晶玻璃的析晶机理。K⁺促进了云母相基本基团[AlSiO₃]的形成。实验证明钙云母晶体的生长过程受界面跃迁过程控制。分析了相组成和显微结构对力学性能的影响及其增强增韧机理。含有大量细小板条形钙云母晶体的微晶玻璃，强度较高。微晶玻璃的断裂韧性随云母晶粒长径比的提高而提高，且存在有多种增韧作用：t-ZrO₂相变增韧、裂纹偏转增韧等。论述了云母基微晶玻璃的增强机理，计算晶粒长径比大于8时，晶体可通过裂纹偏转、晶粒补强增韧使材料具有较好的力学性能。讨论了不同长径比晶粒的增韧效果。 按材料特点设计组成，采用二步法热处理，制得了以钙云母为主相的微晶玻璃，强度高达235MPa，断裂韧性最高2.17Mpa.m^1/2。此材料具有一定的可切削性。更多还原

【Abstract】 Machinable glass ceramics (MGC) can be machined with conventional tools. In the conventional mica-based MGC, the weak bonding between tetrahedron-octahedron-octahedron at layers of mica leads to low strength. In the paper on the base of materials design and calculation in mica MGC system, the partly-substitution K+ by Ca2+ doubly strengthens bonding force between layers, then increases the strength of mica crystal in itself. At the same time, high strength mica-based MGC can be prepared by doping zirconia to strengthen and toughen. The study on preparation process, microstructure, strengthening and toughening mechanisms of MGC mainly containing Ca-mica were investigated, together with mechanical properties and machinability.Crystallization mechanisms were probed in the CaO-MgO-Al2O3-SiO2-F system in the study. K+ promoted mica’s basic unit [AlSiO3] to form zirconia provided nucleating site for planar like mica crystal. The fracture toughness of the material improved with the increase in aspect ratio of mica crystal, and several existing toughening mechanisms were the phase transformation from t-ZrO2. The better mechanical properties attributed to the reinforcement and the crack deflection of crystals with aspect ratios over 8. Effect of different aspect ratios of crystals on toughen was discussed.With the special design, the MGC mainly containing Ca-mica crystals was prepared using two-stage heat treatment; the highest bending strength is 235MPa and the corresponding toughness is 2.17 MPa.m1/2, which was better than that of currently MGC. The results of machinability evaluation test showed that the material is easy to machine.更多还原