【作者】 赵文济；

【导师】 李戈扬；

【作者基本信息】 上海交通大学 ， 材料学， 2007， 硕士

【摘要】 以TiN为代表的陶瓷硬质薄膜在刀具涂层上的成功应用有力地推动了制造业的发展。高速、干式切削等加工技术的进步对刀具涂层提出了更高的要求。作为一种通过微结构设计强化的材料,纳米多层膜不仅可因其超硬效应获得高硬度,而且可以通过选择材料组合获得其他优异性能,因而纳米多层膜作为新一代刀具涂层材料而备受关注。鉴于已有的纳米多层膜产生强化的超硬效应研究,以及纳米多层膜中晶体层强制非晶层晶化的模板效应的微结构研究,其理论分析和实验研究多以NaCl结构的立方晶系所展开,本论文采用六方晶系的纤锌矿结构AlN（h-AlN）作为纳米多层膜的晶体层,研究了SiO₂和Si₃N₄非晶层在h-AlN晶体层上的晶化现象以及AlN/SiO₂和AlN/Si₃N₄纳米多层膜的生长结构、超硬效应和强化机制;考察了AlN/SiO₂纳米多层膜的高温抗氧化性,并且讨论了氧化物层的加入对纳米多层膜抗氧化性的影响。研究结果表明:在AlN/SiO₂和AlN/Si₃N₄纳米多层膜中,六方晶体的AlN模板层能够使沉积态为非晶的SiO₂和Si₃N₄在调制层厚度小于约0.6 nm时晶化为六方结构的赝晶体,并与AlN层形成共格外延生长结构,多层膜呈现出硬度升高的超硬效应,最高硬度分别达到29.1 GPa和32.8 GPa。SiO₂和Si₃N₄随层厚的进一步增加又逐渐转变为以非晶态生长,多层膜的外延生长结构遭到破坏,硬度亦随之降低。对于AlN/SiO₂和AlN/Si₃N₄纳米多层膜,根据模量差理论定量计算所得的硬度增量远小于实际测量值,表明模量差强化仅仅占到多层膜硬度提高的一小部分。基于高分辨透射电子显微镜观察到多层膜中存在晶格错配而产生拉压交变应力场,本论文利用共格应变的理论模型进行计算,得到的硬度增量与实际的增量相当。分析认为,两调制层形成共格更多还原

【Abstract】 The application of ceramic thin hard films, such as TiN, on cutting tools remarkably promoted the development of manufacturing industry. With the advancement of high-speed and dry cutting technology, it needs much high requirements for the protection coatings on cutting tools. As the kind of materials that are reinforced by microstructure design, nano-multilayers can not only reach high hardness by the superhardness effect, but also obtain other excellent properties by properly choosing the combination of modulation materials. As a result, nano-multilayers are receiving increasing attentions and researches as a new generation of protection coating.Former researches on superhardness effects and template effects in multilayers are mainly on NaCl structure materials. However, this thesis adopt h.c.p. structured wurtzite AlN（h-AlN） as the crystal layer in the multilayers. The crystallization behavior of SiO₂ and Si₃N₄ under the effects of h-AlN is studied. The superhardness effects as well as the mechanism of hardness enhancement are also investigated. In this thesis, the high temperature oxidation resistance of AlN/SiO₂ are experimental studied. And the effects of SiO₂ addition to the high temperature ability of the multilayers are also discussed.The results are showed as follows. In AlN/SiO₂ and AlN/Si₃N₄ nano-multilayers, due to the h.c.p. AlN template layers, normally amorphous SiO₂ and Si₃N₄ crystallize and form h.c.p. pseudo-crystal structure when their thickness is below 0.6 nm. The crystallized materials grew epitaxially更多还原