【作者】 赵岳；

【导师】 刘宁；

【作者基本信息】 合肥工业大学 ， 材料学， 2002， 硕士

【摘要】 氮化硅复合陶瓷具有优良的物理、力学性能和耐磨、耐腐蚀特性，因而受到人们的广泛关注；但是该材料的脆性断裂特性依然存在，而且其机械可靠性也不尽如意，因此有必要进一步深入研究以充分发挥其性能优点。细化晶粒改善陶瓷性能是当前研究的热点。本文用热压方法制备了细晶氮化硅／氧化铝复合陶瓷，并对该材料的原料粉末的特性、烧结工艺、致密特性及力学性能进行了比较深入的实验研究和理论探讨，为下一步研究打下实验和理论基础。 首先研究了原料粉末的性能。研究发现原料粉末的团聚特性、氧吸附性对材料的烧结工艺、力学性能影响较大；对原料粉末在1200℃下进行热处理，可以使原料粉末转晶和钝化，最终烧结成细晶复合陶瓷。 其次研究了烧结温度和气氛对细晶陶瓷致密特性、力学性能的影响。随着烧结温度升高，材料的致密度上升，抗弯强度和硬度提高，但断裂韧性的变化与添加剂有关；当烧结气氛是氮气时，能有效地抑制原料粉末的分解和氧化；而当烧结气氛是氩气时，则会发生较严重的氧化现象。 再次研究了烧结添加剂种类对该材料的致密特性、力学性能的影响。随着烧结添加剂种类的增加，在相同温度下材料的致密度上升，力学性能提高。但当添加剂中氮含量升高到一定程度时就会得到相反的结果。 最后研究了烧结添加剂的数量对该材料的致密特性、力学性能的影响。随着烧结添加剂量的增加，在相同温度下材料的致密度上升，力学性能的变化与材料中的致密度、第二相粒子及晶间相有关。更多还原

【Abstract】 SisN’-based composite ceramics have attracted attention owing to itsoutstanding physical, mechanical properties and high wear-resistance, gooderosion-resistance. But the fatal brittleness still exists in these materials, and themechanical reliability is also low. The fine crystalline ceramics was researchedpopularly at present. In this thesis, the fine-crystalline Si3N4/Al2O3 compositeceramics were prepared by hot pressing. The phenomena including the properties ofpowder, sintering process, densification and mechanical properties were discussedby the experimented research and theoretical analysis. The experimenta1 andtheoreticaI basis has been presented for further research.First, the research on the properties of powders was done. The resultsrevealed that the formation of agglomerates and the absorbed oxygen affected thesintering process and mechanical properties of these fine-crystalline materials.When the powders have been heat-treated at 1200C, the fine crystalline materia1shave been obtained due to the phase transformation and thermal inactivation.Second, the research on the effect of the sintering temperature and theprotective gas on the densification and the mechanical properties of these materialswas worked on. The higher the sintering temperature, the higher the density. thebetter bend strength and hardness. but the variation of fracture toughness propertiesdepended on the kind of addition. When the protective gas was N2, the oxidationand the decomposition have been pressed. But when Ar was used, the seriousoxidation has been happened.Third, the research on the effect of the kind of addition on the densificationand the mechanical properties of these materials was conducted. Under the sametemperature, with the increase of the sort of the additions, the density and themechanical properties of these materials have increased. But a proper proportion ofnitrogen in the addition should been defined, otherwise, a contrary result has beenrec eived.Last, the research on the effect of the quantity of addition on the densificationand the mechanical properties of these materials was done. Under the sametemperature, with the increase of the quantity of the additions, the density hasincreased, and the variation of the mechanical properties of these materialsdepended on the density and the quantities of the second-phase particle and intercrystalline phase of these materials.更多还原