【作者】 殷卫海；

【导师】 刘宁；

【作者基本信息】 合肥工业大学 ， 材料学， 2006， 硕士

【摘要】 细化晶粒,是提高合金强韧性的有效方法。本文即是出于此目的,考虑在原料成分和制备工艺一定的情况下,观察原始粉末尺寸对Ti(C,N)基金属陶瓷组织性能的影响,找出粉末粒度因素与材料的组织和性能之间的规律关系。 首先,本文简要地概述了Ti(C,N)基金属陶瓷的发展背景、目前面临的问题和以后的发展趋势,以及当前Ti(C,N)基金属陶瓷的几大研究热点:硬质相/粘结相的相界面研究、各种添加剂的作用以及原料粉末尺寸因素的影响。 其次,本文第三章介绍了材料的制备过程,指出:制备过程中,粉体混合的均匀程度、压制压力的选择以及烧结工艺的选择和过程的控制是决定材料组织和性能的关键步骤。第四章介绍了Ti(C,N)基金属陶瓷材料的几个主要性能参数,并简要说明了其测试方法和所用仪器。 最后,本文第五章分析了原始粉末粒度对材料组织和性能的影响,第六章指出了该方面下一步的工作重点: (1) 粒度的变化,材料中没有新相生成;随着粒度的减小,Ni/Co粘结相的固溶元素的量增多,XRD衍射峰的偏移量增大; (2) 显微组织中出现较多的“黑芯-灰壳”结构,随着原始粉末TiC、TiN粒度的变细,材料组织中硬质相的粒度也变细,并且组织中“白芯-灰壳”结构也出现的越多。EDS分析可知,黑色芯部主要为TiC或Ti(C,N),灰色的壳层为(Ti,W,Mo)(C,N),而白色的壳层多为含W、Mo的粘结相Ni/Co;白色芯部主要为WC或(W,Mo)(C,N)固溶体;组织中还出现数量较少的白色内壳层。 (3) 随主要硬质相TiC/TiN粒度的减小,材料的抗弯强度逐渐增强,并且幅度变化较大;材料的断裂韧性却会降低,这主要是因为细粉制备的材料粘结相中固溶元素较多,粘结相强度增大,而韧性降低;以及细原料粉中吸附的氧或杂质量比较高,减弱了粘结相/硬质相之间的相界面结合强度,材料断裂韧性降低。粒度对硬度的影响不大。 (4) 以后的研究重点应该放在更微观的相界面研究上。更多还原

【Abstract】 As we know, grain refinement is an effective method to improve the strength and toughness of the alloy material. From this view, we have researched the influence of powder size on the microstructure and mechanical properties of Ti(C,N)-based cermets on the condition of identical component and fixed preparation technology, and have found the relationship of initial powder size and the microstructure and mechanical properties.Firstly, we briefly introduced the development history, the questions and difficulty in the present study and the future trend of Ti(C,N)-based cermets. At the same time, several present researching emphasis were reviewed, such as: the study on the phase interface between hard phase and binder, the effectiveness of addition agents and powder size on the microstructure and mechanical properties.Secondly, In chapter three ,we pointed out that the homogeneous degree of powder mixture, the choice of pressure force in pressing and the control of the technology in sintering were the key steps to determine the microstructure and properties of cermets in the preparation process. In chapter four, we simply instructed the equipment needed by testing method of main mechanical properties parameters of Ti(C,N)-based cermets,Finally, we analyzed the effectiveness of initial powder size on the microstructure and properties of cermets in chapter five. And we pointed out the future emphasis in this aspect in chapter six. Results show that:(1) Though powder size changed, no new phase formed. With the refinement of the powder size, the amount of solid solution element in Ni/Co binder and the side-play amount of XRD diffraction peak increased.(2) There are many black-core and gray-rim phases in microstructure. With the refinement of the initial powder size of TiC/TiN, the grain size of hard phase become fine, and white-core phase become more. By EDS energy spectrum analyzing, we know that the black-core phase is mostly made up of TiC/ Ti(C,N),gray rim is (Ti,W,Mo)(C,N),the white rim is Ni/Co binder which contains more W and Mo elements and the white-core phase mostly is WC or (W,Mo)(C,N) solid solution;Besides, we also found few white-inner rim in the microstructure.(3) With the refinement of the initial powder size of TiC/TiN, the binding strength increases and changes more, the fracture toughness reduces, and thehardness varies little. The cause is as follows: (a)In the cermets made from the fine powders, the amount of solid solution element in Ni/Co binder is greater, so toughness reduces;(b) the surface energy of fine grain is greater and the raw material contains too more oxygen or other contaminates which reduces the wettability between binder and hard phase, the bond strength of phase interface is weakened, so the fracture toughness of cermets reduces.(4) The future emphasis of investigation on Ti(C,N)-based cermets should focus on the research of the phase interface between hard phase and binder,更多还原