【作者】 陈希来；

【导师】 李远兵；

【作者基本信息】 武汉科技大学 ， 材料学， 2007， 硕士

【摘要】 Ti(C_1-xN_x)（0≤x≤1）,具有高的熔点、高的硬度、相对高的热导率和导电性能,优良的抗磨损等性能,使其在各个领域都具有广泛的应用前景。目前,在工业化生产中普遍采用碳热还原法来制备Ti（C, N）,但该方法存在原料混合难以均匀,反应时间较长,合成温度高等缺点;熔盐法在制备陶瓷粉体方面具有显著降低合成温度和缩短反应时间、较好的控制合成粉体的尺寸和形貌、适应性强、成本低等独特的优势,若将二者结合起来,则可能制备出性能优良的Ti（C, N）粉末。目前,将Ti（C, N）应用在耐火材料中却鲜有报道,如果将Ti（C, N）等非氧化物作为添加剂引入到高炉用炭砖中,则可能提高炭砖的强度、耐磨性、抗热冲击和抗熔体侵蚀性等。本文就以下三部分进行了研究:第一部分通过对不同的工艺因素研究表明:在熔盐介质中以TiO₂和炭黑为原料来合成Ti（C, N）,在氮气或埋炭气氛下,最佳的碳钛摩尔比约为2 : 1,反应在氮气气氛下进行的更充分;在埋炭气氛下,添加10wt%熔盐且热处理温度为1300℃×3h较好;熔盐为多组分且含有加热过程中能分解放出气体的对反应有利;原料混合时间一般为湿混30min;炭黑的粒度小、活性大对反应有利;小批量生产验证了实验的可行性。第二部分通过熔盐浴中合成Ti（C, N）的研究表明:熔盐对合成Ti（C, N）有极大的促进作用,能有效降低反应温度和控制粒子形貌;制备的Ti（C, N）粒子的平均尺寸约为2⁶μm,且形状规则,颗粒间团聚较小;分析其反应过程为TiO₂→Ti₄O₇→Ti₃O₅→TiO_xN_y→Ti（C, N）。第三部分研究了Ti（C, N）等不同添加剂对炭砖性能影响,结果表明:添加TiC和TiO₂+Al试样的体积密度最大,显气孔率最小,且加入TiO₂+Al试样的耐压强度最大;物相分析表明,金属Si在热处理过程中转化为SiC、Si2N2O以及石英,同时,TiO₂转化为Ti（C, N）;600℃下,添加TiC试样的导热系数最大,其值为15.03W/m.k;添加TiO₂+Al试样的小于1μm孔容积值最大,为78.5%,且孔径主要集中在200nm左右;显微结构分析发现,添加TiO₂+Al试样的结构最致密,而只加TiO₂的结构疏松且有很多明显的气孔和裂纹;通过比较发现,以TiO₂+Al作为添加剂来改善和提高炭砖的性能最佳,但其配比和加入量需进一步研究。更多还原

【Abstract】 Ti(C_1-xN_x)（0≤x≤1） has many excellent advantages, such as high melting point, big hardness, relatively high thermal and electrical capability, good abrasion resistance, which make it has various applications in different areas. At present, carbothermic reduction and nitridation method is generally used to fabricate Ti（C, N） powder, however, such disadvantages as non-mixed mixtures, long reaction time and high combustion temperature existing. Molten salt method owes exclusive super-advantages in preparing ceramics powders, it can decrease initial synthesis temperature and reduce reaction time remarkably, effectively control the powder’s particle size and morphology, has wide application and low cost etc. If the two methods are combined, it is likely to synthesize Ti（C, N） powder with excellent properties. Nowadays, Ti（C, N） used in refractory materials is extremely less reported. The properties of carbon brick such as strength, wear resistance, thermal shock resistance and molten iron corrosion resistance may be improved significantly when the non-oxides of titanium as Ti（C,N） is added. The work investigated contains three parts as follows:Firstly, the affection parameters in experimental procedure are investigated and the results indicate that, in the presence of molten salt and using TiO₂ （anatase type） and carbon black as raw materials, the reasonable molar ratio of C and TiO₂ determined was 2 in both atmospheres of coked condition and nitrogen gas, however, the reaction performed more completely in nitrogen gas atmosphere. Ideal yield of Ti（C, N） powder was obtained in the presence of 10wt% molten salt at 1300oC for 3h. Molten salt containing several kinds and one or more can dissolve and give out gas is favorable for the formation of Ti（C, N）. The wet mixing time for the raw materials chosen was 30 min. Carbon black is as the most effective carbon source because of it’ smaller particle size and high reactive ability. The possibility of mass production was identified by mid factory production.Secondly, Ti（C, N） prepared in molten salt bath shows that molten salt has a positive effect on the reaction occurrance, which effectively decreased initial reaction temperature and well controlled the particle morphology. The Ti（C, N） obtained, mean particle size was about 2⁶μm, uniform shape and less extent agglomeration. The possible reaction route was TiO₂→Ti₄O₇→Ti3O5→TiOxNy→Ti（C, N）.Thirdly, effects of different kinds of additives on coked carbon brick’ properties were investigated and the results show that the specimens containing TiC and TiO₂+Al as additives, have the biggest bulk density and the smallest apparent porosity, meanwhile, the specimen containing TiO₂+Al has the biggest cold compressive strength. The XRD analysis point out that metallic silicon converted into SiC、Si₂N₂O and quartz, meanwhile, TiO₂ transformed to Ti（C, N） after coking. The thermal conductivity coefficient of fired carbon brick was measured in 600oC and the results showed that the specimen adding TiO₂+Al has the biggest value of 15.03W/m.k.The value of <1μm pore volume, 78.5% in TiO₂+Al specimen was the biggest , and the pore size was mainly concentrated at about 200 nm. By comparing specimens’microstructures, it is found that the TiO₂+Al specimen has the densest structure while the TiO₂ specimen has a loose structure with many optical pores and cracks apparently. Conclusions can be drawn from the results above mentioned, TiO₂+Al can be used as the effective additive to improve the carbon brick’ properties, but the ration and addition content of TiO₂ and Al should be investigated furthermore.更多还原