导　　师： 傅正义;张金咏

学科专业： 080502

授予学位： 硕士

作　　者： ;

机构地区： 武汉理工大学

摘　　要： TiB/_2陶瓷具有优良的物理化学性能和机械力学性能，它除了具有非常高的硬度和弹性模量外，还表现出一系列良好的特性——导电性、高熔点、耐磨损、重量轻以及高的化学稳定性，其应用前景十分广阔。但是TiB/_2材料较高的制作成本以及较差的烧结性为制备带来了困难，同时TiB/_2的常温脆性阻碍了它的实际应用。本文选择AlN为第二相，采用热压法制备TiB/_2-AlN复相陶瓷，研究了不同的AlN含量和烧结工艺对材料机械性能的影响，分析了材料显微结构和性能之间的关系，并研究了不同的烧结助剂对TiB/_2-AlN材料性能的影响。 AlN的加入可以明显提高材料的烧结性能，在AlN含量为0-30vol.％变化时，材料的相对密度都达到96％以上，可以发现在AlN含量时5vol.％得到材料的相对密度最高，达到97.2％。随着AlN含量的增加，材料的机械性能先上升后下降，在5vol.％含量时，性能最好。 选择相同AlN含量和纵向压力/(30MPa/)研究了烧结温度/(1700℃-1900℃/)和保温时间/(0.5h-3h/)对烧结过程的影响，当烧结温度升高时，材料的硬度和弯曲强度是先增大后减小，延长保温时间也得到相同的规律。得到实验结果为：在烧结温度为1800℃，保温时间为1小时，AlN含量为5vol.％时，可以得到显微硬度为23.3GPa；弹性模量和抗弯强度分别为461GPa和648MPa；材料的断裂韧性达到6.91 MPa·m~/(1／2/)。 Y/_2O/_3和NbB/_2做为烧结助剂都可以提高TiB/_2-5vol.％AlN的相对密度，但Y/_2O/_3的加入使得TiB/_2-AlN材料的机械性能有了明显的下降，添加NbB/_2到材料中可以使其相对密度达到98.7％，并提高了材料的机械性能，在添加量为5vol.％时复合材料可以获得682MPa的抗弯强度和7.06 MPa·m~/(1／2/)的断裂韧性值。 显微结构研究表明：TiB/_2颗粒大小比较均匀，AlN比较均匀的分散在TiB/_2� TiB/_2 ceramics have excellent physical-chemical properties and mechanical properties. Apart from its extremely high hardness and elastic modulus, TiB/_2 exhibits high electrical conductivity; melting temperature and wear resistance, low specific weight and relatively good chemical stability. TiB/_2 ceramics are very promising in modern industry. The main problems that the application of TiB/_2 ceramics include: high price of TiB/_2 raw materials, low sintering activity and the inherent brittleness. Adding of secondary phase is an important way to improve the mechanical properties of ceramics. In this paper, TiB/_2-AlN multiphase ceramics were prepared by hot pressing technology with A1N as an additive. The effects of aid content, sintering temperature and holding time on mechanical properties of TiB/_2 ceramics were studied, the relationship between microstructure and mechanical properties was analyzed. And the effect of other aid to TiB/_2-AlN ceramics was discussed. It improved the sintering ability that AlN was added. Relative density of the ceramic got above 96/%, compared with 90/% when added none into TiB/_2. And materials showed the high relative density /(97.2/%/) when A1N content was 5vol./%. With the increasing of A1N content, mechanical properties increased to max. at 5vol. /% and then decreased. The effects of the sintering temperature /(1700°C-1900°C/) and holding time /(0.5h- 3h/) to properties were studied at the same A1N content. With the prolong of soaking time, the hardness and the blending strength of the materials increased to max. and then decreased. The same trend was found at sintering temperature increased. It was found that the better properties were got when sintered at 1800°C for holding 1h. The specimen sintered at this condition gave 23.3GPa for Vickers hardness, 461GPa for bending strength, 648MPa for young's modulus and 6.91 MPa·m ~/(1//2/) for fracture toughness. Adding Y/_2O/_3 /& NbB/_2 could improve the relative density of TiB/_2-5vol./%

关 键 词： 陶瓷 热压烧结 机械性能 显微结构

领　　域： [化学工程] [化学工程]