TiSiN纳米晶复合陶瓷材料合成、结构表征及性能研究

发布时间：2018-04-30 10:00

本文选题：纳米晶-非晶复合结构 + 力学性能　；参考：《武汉大学》2016年博士论文

【摘要】：切削加工行业正在向着高速干切削的方向发展,对刀具及其涂层材料提出了更高的使用要求。TiSiN材料具有高硬度、高热稳定性以及高耐蚀的特点,在刀具上具有良好的应用前景,但对其结构、性能以及应用的系统研究较少。本文采用多弧离子镀(CAIP)技术在纯氮气氛下沉积了不同硅含量靶材的TiSiN单层及多层复合涂层,利用SEM、 XRD、XPS、TEM、AFM等测试方法表征涂层的结构,并利用纳米压痕技术与摩擦磨损仪器测试了涂层力学性能与摩擦性能,探讨了TiSiN涂层工艺参数与性能之间的关系以及多层复合技术带来的性能改善。其次,本文系统研究了TiSiN涂层的高温抗氧化性能、抗腐蚀性能以及抗辐照性能,探讨TiSiN作为抗氧化与防腐蚀保护涂层的应用可能性并提出了TiSiN的辐照损伤机理。此外,本文利用SPS技术成功制备三维块体TiSiN材料,提出了其结构与硬度强化机理。主要结果如下：(1)采用CAIP技术在纯氮气中,利用合金靶材作为硅源,成功制备高硬度、低摩擦的纳米复合结构TiSiN涂层；沉积过程中氮气气压升高会影响到涂层化学成分,并且晶体生长从(111)转为(200),晶粒尺寸减小,涂层硬度与电阻值升高,摩擦系数也逐渐增大,当氮气升高到2.5Pa之后,合金靶材出现中毒现象；另外,随着靶材Si含量升高,涂层中Si含量随之升高,最后趋于稳定,涂层中TiN晶体由(111)生长方向逐渐转向(200)方向,涂层晶粒尺寸由18.9nm逐渐减小到5.6nm,硬度值随之增高,最大硬度40.7GPa在靶材Si含量为20 at.%时获得；TiSiN多层复合涂层实验表明,多层涂层的层间界面能够增强涂层硬度并且降低涂层摩擦系数,沉积过程中转速会改变涂层的调制周期,当TiN/TiSiN涂层调制周期减小时,TiN(111)晶面强度升高,当调制周期为23nm时,涂层获得最大硬度3413HV,与最小摩擦系数0.49。(2)TiSiN涂层摩擦系数与磨损率均小于TiN涂层,涂层的摩擦系数以及磨损速率均随着Si含量增加而升高；并且随着Si含量升高,涂层摩擦方式由粘着磨损、磨屑磨损变为单一的磨屑磨损；TiSiN涂层具有优异的抗腐蚀性能,并且随着Si含量升高抗腐蚀性能增强,长时间浸泡实验表明,涂层腐蚀主要是表面颗粒与孔洞优先腐蚀,使得过渡层与基底被腐蚀,导致涂层与基体剥离；TiSiN涂层高温氧化实验表明该涂层可以在800℃温度使用,涂层中细小晶粒以及内部致密的Si3N4非晶结构能够有效阻碍内部合金元素以及外部氧元素的扩散,延缓氧化进行。(3)辐照条件下,TiSiN涂层出现了非晶化,由此导致涂层的硬度、杨氏模量的下降；并且研究发现,TiSiN涂层抗辐照性能随着涂层内部晶粒减小而增强,其原因在于涂层内部纳米晶-非晶界面能够促进辐照过程中间隙原子与空位点缺陷的融合,但存在一个最优化的晶粒尺寸。(4)三维TiSiN块体材料为纳米TiN与非晶Si3N4复合结构,TiN纳米晶被非晶Si3N4包围,材料致密度、晶粒尺寸随着非晶Si3N4比例升高而减小,硬度与杨氏模量则随之升高,但当Si3N4的晶粒细化与硬度强化都具有一个临界比例。Si3N4在烧结过程中能够阻挡原始纳米TiN晶粒融合长大的过程以及晶体内部位错运动,因此带来晶粒细化与硬度强化效果,但是Si3N4比例升高将会提高材料TiSiN所需的烧结温度,因此导致材料内部出现空隙,致密度下降,引起晶粒粗大与硬度降低。
[Abstract]:The cutting and machining industry is developing towards the direction of high speed dry cutting, and the higher use of cutting tools and their coating materials requires that.TiSiN materials have high hardness, high thermal stability and high corrosion resistance, and have good application prospects on the cutting tools. But there is less research on the structure, energy and application of the materials. TiSiN monolayer and multilayer composite coating with different silicon content were deposited by arc ion plating (CAIP) technology in pure nitrogen atmosphere. The coating structure was characterized by SEM, XRD, XPS, TEM, AFM and other testing methods. The mechanical properties and friction properties of the coating were tested by nano indentation and friction and wear instruments. The process parameters of TiSiN coating were discussed. The relationship between performance and the performance improvement of multi-layer composite technology is improved. Secondly, the high temperature oxidation resistance, corrosion resistance and radiation resistance of TiSiN coating are systematically studied. The application possibility of TiSiN as antioxidation and corrosion protection coating is discussed and the radiation damage mechanism of TiSiN is proposed. In addition, this paper uses SPS The structure and hardness strengthening mechanism of 3D block TiSiN materials are successfully prepared by technology. The main results are as follows: (1) using CAIP technology in pure nitrogen and using alloy target as the silicon source, the nano composite TiSiN coating with high hardness and low friction is successfully prepared. The increase of nitrogen gas pressure in the process of deposition will affect the chemical composition of the coating. And the crystal growth changed from (111) to (200), the grain size decreased, the hardness and resistance value of the coating increased and the friction coefficient increased gradually. When nitrogen increased to 2.5Pa, the alloy target was poisoned. In addition, the content of Si in the coating increased with the increase of the target Si content, and finally tended to be stable. The TiN crystal in the coating was produced by (111). In the direction of gradually turning (200), the grain size of the coating gradually decreases from 18.9nm to 5.6nm, the hardness value increases and the maximum hardness 40.7GPa is obtained at the target Si content of 20 at.%. The TiSiN multilayer composite coating experiment shows that the interlayer interface of multilayer coating can enhance the hardness of the coating and reduce the friction coefficient of the coating. When the modulation period of the coating is changed, when the modulation period of the TiN/TiSiN coating is reduced, the strength of the TiN (111) crystal surface increases. When the modulation period is 23nm, the coating obtains the maximum hardness 3413HV. The friction coefficient and wear rate of the 0.49. (2) TiSiN coating are both less than the TiN coating, and the friction coefficient and wear rate of the coating increase with the Si content. And as the content of Si increases, the friction mode of the coating is worn from adhesive wear to the single abrasive wear. The TiSiN coating has excellent corrosion resistance, and the corrosion resistance of the coating is enhanced with the increase of Si content. The corrosion of the coating in a long time shows that the corrosion of the coating is mainly corrosion of the surface particles and holes. The layer and substrate are corroded, resulting in the stripping of the coating and the matrix, and the high temperature oxidation experiment of TiSiN coating shows that the coating can be used at 800 temperature. The fine grain in the coating and the dense Si3N4 amorphous structure can effectively obstruct the diffusion of the internal alloy elements and the external oxygen elements and delay the oxidation. (3) TiSiN coating under irradiation conditions. The crystallization of the coating leads to the hardness of the coating and the decline of the young's modulus, and it is found that the radiation resistance of the TiSiN coating increases with the decrease of the internal grain size of the coating. The reason is that the nanocrystalline amorphous interface in the coating can promote the fusion of the gap atoms and the vacancy point defects in the irradiation process, but there is an optimization. The grain size. (4) the three-dimensional TiSiN block material is the composite structure of the nano TiN and the amorphous Si3N4, and the TiN nanocrystals are surrounded by amorphous Si3N4, the density of the materials, the grain size decreases with the increase of the amorphous Si3N4 ratio, and the hardness and Young's modulus increase, but the grain refinement and hardness strengthening of Si3N4 have a critical proportion of.Si3N4 in burning. During the process, the process of grain fusion and growth of the original nanocrystalline TiN and the internal dislocation movement in the crystal bring about grain refinement and hardness enhancement, but the increase of Si3N4 ratio will increase the sintering temperature required for the material TiSiN, thus leading to the appearance of void in the material, the decrease of density, and the coarse grain and the decrease of hardness.

【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG174.4;TG71

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