SPS制备NiTi表面多孔梯度合金的组织与性能研究

发布时间：2018-01-05 00:05

  本文关键词：SPS制备NiTi表面多孔梯度合金的组织与性能研究　出处：《昆明理工大学》2017年硕士论文　论文类型：学位论文

  更多相关文章： 镍钛梯度合金 烧结温度 微观组织演变 表面孔隙特征 力学性能

【摘要】：NiTi合金不仅具有高比强度、低弹性模量、良好耐磨耐蚀性、高抗疲劳性等优点,而且还具有优异形状记忆效应和超弹性性能,在脊椎矫形、颅骨修补、牙齿正畸及心血管支架等方面得到了广泛应用。但是该合金属表面无生物活性,很难与骨组织形成长期稳定的骨性结合。通过在NiTi合金中引入孔隙结构形成多孔合金,不仅显著降低了合金弹性模量,而且可以与生物硬组织形成良好匹配提高了生物活性。但是当孔隙率高于某一水平后,多孔合金的强度下降明显,不能满足临床的要求。因此,本文在前期利用SPS技术制备孔隙均匀、不含其他杂质相的多孔NiTi合金基础上,设计并制备了新型NiTi表面多孔梯度合金,其中内层为NiTi合金、外层为多孔NiTi合金层。通过基体保证材料整体力学性能的同时,来提高它的生物活性实现镍钛医用合金性能的多功能化。在此基础上,研究了 SPS烧结温度对NiTi表面多孔梯度合金的显微组织、界面结合情况、孔隙特征、力学性能以及生物相容性的影响及机理。并得出以下结论:(1)利用放电等离子体烧结制备了多孔镍钛合金:烧结温度在800℃～1050℃范围较好,孔隙率随着烧结温度呈递减趋势,由51.6%下降到43.5%。利用放电等离子体烧结制备了N Ti表面多孔梯度合金:650℃时由于烧结温度过低,合金相成分不均匀,单质Ti、Ni相的衍射峰占主导;随着烧结温度升高Ti2Ni、Ni3Ti杂峰和NiTi峰增强,单质相峰逐渐减弱;当烧结温度达到750℃后,单质相的衍射峰基本完全消失,主要由NiTi相组成。650℃时基体与多孔层界面结合较差,随着温度的升高,内外界面逐渐形成稳定的冶金结合,晶粒细化,烧结效果良好。同时温度的提高也使孔内壁内部表面也逐渐变得光滑,表面多孔层的孔隙率呈缓慢下降趋势。但是烧结温提高到800℃后,界面区域不规整统一,达不到梯度合金的设计要求。(2)所制备NiTi表面多孔梯度合金压缩弹性模量随烧结温度升高变化不明显,且与人骨弹性模量非常接近;而抗压强度随烧结温度升高呈显著增大趋势。在模拟人体体液中浸泡两周后,致密镍钛合金并无任何差别,多孔镍钛合金和梯度合金中的多孔结构处沉积一定的磷酸盐颗粒。梯度合金镍离子溶出速率在致密镍钛合金和多孔合金之间,且均低于人体致毒剂量。同致密镍钛合金、多孔镍钛合金相比750℃烧结温度下制备的NiTi表面多孔梯度合金不仅具有良好的界面结合和表面孔隙特征(孔隙率46.1%、平均孔径296μm)、较高的抗压强度(1350MPa)及较低的弹性模量(10.1 GPa),优异的超弹性性能(循环加载卸载27次),而且还具有一定的生物相容性。
[Abstract]:NiTi alloy not only has the advantages of high specific strength, low modulus of elasticity, good wear resistance and corrosion resistance, high fatigue resistance, but also has excellent shape memory effect and hyperelastic properties in spinal orthopedic and skull repair. Dental orthodontics and cardiovascular stents have been widely used, but the metal surface has no biological activity. It is difficult to form a long-term stable bony bond with bone tissue. By introducing pore structure into NiTi alloy to form porous alloy, not only the elastic modulus of the alloy is significantly reduced. But when the porosity is higher than a certain level, the strength of the porous alloy decreases obviously, which can not meet the clinical requirements. In this paper, a new porous NiTi alloy with uniform pores and no other impurity phase was designed and prepared by SPS technique. The inner layer is NiTi alloy and the outer layer is porous NiTi alloy layer. On the basis of this, the microstructure and interfacial bonding of SPS sintering temperature on porous gradient alloy on NiTi surface were studied. Pore characteristics. The influence of mechanical properties, biocompatibility and mechanism. The following conclusion is drawn: 1) porous Ni-Ti alloy was prepared by spark plasma sintering. The sintering temperature is better in the range of 800 鈩，

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