导　　师： 涂铭旌

学科专业： 080502

授予学位： 博士

作　　者： ;

机构地区： 四川大学

摘　　要： 在刀具材料中，从综合性能、经济成本和资源利用等角度考虑，Ti/(C，N/)基金属陶瓷都比WC基硬质合金具有优势。因而，Ti/(C，N/)基金属陶瓷是刀具材料的研究重点之一。近年来发现，用粒度小于1μm的亚微、超细、纳米硬质相粉末制备或添加改性金属陶瓷，可以大大提高Ti/(C，N/)基金属陶瓷的使用性能。然而，现今供商业出售的Ti/(C，N/)粉末的粒度范围一般为0.5～2μm，因而TTi/(C，N/)粉末的细化已成为当今Ti/(C，N/)基金属陶瓷领域的研究焦点之一。 本文在分析现有Ti/(C，N/)粉末制备法的基础上，首先以锐钛型纳米TiO/_2和纳米碳黑为原料，通过低成本的碳热还原氮化法制备Ti/(C，N/)。为进一步促进TiO/_2碳热氮化反应和合成纳米产物，结合高能球磨，在Ti/(C，N/)粉体制备中首次提出“机械激活”与“多重激活”等创新思路，并对其展开了研究。用X射线衍射/(XRD/)、差示扫描量热法/(DSC/)、热重分析法/(TGA/)、X射线光电子能谱/(XPS/)、扫描电镜/(SEM/)、透射电镜/(TEM/)等分析手段对机械球磨和反应过程及产物进行研究。 TiO/_2碳热氮化反应过程的机理目前尚不甚清楚，因此对其进行了研究。结果表明，该过程可分为三个连续阶段：第1阶段为TiO/_2的碳热还原，生成物为一系列中间钛氧化物Ti/_nO/_/(2n-1/)，此阶段反应速率从慢到快；第Ⅱ阶段为Ti/_2O/_3的碳氮化反应或Ti/_3O/_5的氮化反应，生成物为Ti/(C，N，O/)或Ti/(N，O/)，该阶段反应速率最快；第Ⅲ阶段为Ti/(C，N，O/)或Ti/(N，O/)与非金属原子C、N之间的置换反应，最终形成Ti/(C，N/)，这一阶段反应速率最慢。研究也发现，氮气量对反应顺序有重要影响。当密闭反应系统有足够N/_2时为：Anatase→Rutile→Ti/_nO/_/(2n-1/)/(n>10/)→Ti/_nO/_/(2n-1/)/(10≥n≥4/)→Ti/_3O/_5→Ti/(N，O/)→TiN→Ti/(C，N/)；反之，则为：Anatase� Ti/(C,N/)-based cermets has more advantages than WC cemented carbide in tool materials, such as comprehensive properties, economic cost, and resource utilization. Thus it has been one of key research fields in tool materials. Recent years, study results show its performance maybe greatly improved, if Ti/(C,N/)-based cermets was prepared or modified with submicron, ultrafine, or nanosized Ti/(C,N/) powders. However, only commercial submicrometric/(0.5-2μm/) powders are available nowadays on the market. Therefore, many studies have been focused on preparing ultrafine or nanosized Ti/(C,N/) powders. Based on analysis of existing preparation methods, a low-cost method was adopted to prepare Ti/(C,N/) in this study. That is, Ti/(C,N/) was synthesized by Carbothermal Reduction-Nitridation/(CRN/) method from mixtures of nanosized anatase and carbon black. For acceleration of CRN reaction and synthesis of nano-Ti/(C,N/), two new ideas involved in mechanical milling, i.e. mechanical activation and multiple activation, were brought forward and carried out in preparation of Ti/(C,N/) powders. The mechanical milling processes, CRN reaction sequences, and characterization of powders in the various states were analyzed using X-ray diffraction/(XRD/), differential scanning calorimetry/(DSC/), thermogravimetric analyzer/(TGA/), X-ray photoelectron spectroscopy/(XPS/), scanning electron microscope/(SEM/), transmission electron microscope/(TEM/). To this day, reaction mechanism of TiO/_2 CRN was still very unclear, thus it was investigated in this paper. The experiments confirm that TiO/_2 CRN processes can be divided into three continuous stages. In the first stage, TiO/_2 was reduced to a series of intermediate titanium oxide/(Ti/_nO/_/(2n-1/)/), and reductive reaction rate is from slow to fast. In the second stage, Ti/(C,N,O/) was formed by carbonization and nitridation reaction of Ti/_2O/_3,or Ti/(N,O/) was formed by nitridation reaction of Ti/_3O/_5, and its reaction rate is the biggest among three stages. In

关 键 词： 纳米 碳热氮化反应 机械激活 多重激活 反应球磨

领　　域： [一般工业技术]