应力对钛在模拟体液中沉积磷灰石的影响

发布时间：2018-06-26 10:08

本文选题：碱热处理 + 应力　；参考：《山东大学》2012年硕士论文

【摘要】：本文以工业纯钛为研究对象,通过碱热处理和模拟体液(SBF)浸泡的方法,在其表面生成羟基磷灰石层(HA),用折弯法模拟了人体内部应力环境,并采用X射线衍射仪(XRD)、场发射扫描电子显微镜(FE-SEM)、能谱仪(EDS)和金相显微镜等表征分析仪器,研究了应力作用下HA涂层的组织结构形态、相组成和应力影响特征。结果表明,在应力作用下,生成的HA的厚度随应力改变呈规律性变化,这也说明应力影响了钛表面的生物活性。当处于压应力作用下,磷灰石层的厚度比正常状态下薄很多,但是随着压应力增大,磷灰石层厚度不再发生明显变化；当处在拉应力作用下,磷灰石厚度比无应力状态下厚,且应力值越大,厚度越大。这主要是由于在压应力作用下,碱热层(或钛)表面孔隙闭合,导致磷灰石的沉淀速度下降；在拉应力作用下,孔隙张开,更大的孔隙有利于磷灰石的沉淀。从钛试样正面观察应力的作用效果发现,磷灰石层上普遍存在裂纹,在无压力的状态下,这些裂纹夹角呈120。；在应力作用下,磷灰石层被裂纹分割成近似长方形板块,并随着拉应力增大板块被拉长,随着压应力板块被压缩。这说明压力影响了钛表面磷灰石的生长方式。这种现象可能是由于表面的孔隙会促进磷灰石的沉积,应力的作用会使碱热层表面的缝隙沿着垂直应力的方向延伸或闭合,这样就会促进或减缓该方向的磷灰石沉积,使磷灰石的生长产生方向性。当磷灰石方向生长时,与该方向垂直的方向就会呈现磷灰石较薄的趋势,这使得该方向上裂纹容易出现,压力越大,磷灰石的方向性生长也就越明显,从而裂纹的延伸也就越明显,就呈现出这种应力对于裂纹的指向性现象。本文着眼于生物材料植入人体时,应力对初期的磷灰石附着情况的影响,利用SBF溶液,动态的模拟金属钛在人体环境中在体液和应力的综合影响下表面发生的一系列变化。本文的试验目的是希望通过对应力影响磷灰石生长的研究,说明在生物材料设计和使用过程中,这种磷灰石生长的差异性,可能会导致生物材料在使用时的失效,以及在界面上发生与无应力分析不同的反应,进而证明应力很可能成为今后生物材料研究中比较重要的一个影响因素,特别是在体外模拟试验中,更可能是不可或缺的影响因素。
[Abstract]:In this paper, hydroxyapatite layer (HA) was formed on the surface of titanium by alkali heat treatment and simulated body fluid (SBF) immersion. The stress environment of human body was simulated by bending method. X-ray diffractometer (XRD), field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDS) and metallographic microscope were used to study the microstructure, phase composition and stress effect of HA coating under stress. The results show that the thickness of the generated HA changes regularly with the stress change under the stress, which also indicates that the stress affects the bioactivity of titanium surface. Under compressive stress, the thickness of apatite layer is much thinner than that under normal condition, but with the increase of compressive stress, the thickness of apatite layer does not change obviously, and when under tensile stress, the thickness of apatite layer is thicker than that of non-stress state. And the greater the stress value, the greater the thickness. This is mainly due to the closure of pores on the surface of alkali hot layer (or titanium) under compressive stress, which results in the decrease of the precipitation rate of apatite, and the opening of pores under tensile stress is favorable to the precipitation of apatite. Observing the effect of stress on the front of titanium specimen, it is found that there are generally cracks in apatite layer, and the angle of these cracks is 120.Under the stress, the apatite layer is split into nearly rectangular plates by cracks. The plate is elongated with tensile stress and compressed with compressive stress. This indicates that pressure affects the growth mode of apatite on titanium surface. This phenomenon may be due to the fact that the pores on the surface promote the deposition of apatite, and the effect of stress on the surface of the alkali thermosphere extends or closes along the direction of vertical stress, which in turn promotes or slows down the apatite deposition in that direction. Direct the growth of apatite. When the apatite grows in the direction of the apatite, the vertical direction of the apatite tends to be thinner, which makes the cracks in this direction easy to appear, and the higher the pressure, the more obvious the directional growth of the apatite. The more obvious the crack extension is, the more directionality of the stress to the crack. This paper focuses on the effect of stress on initial apatite adhesion when biomaterials are implanted into human body. By using SBF solution, the dynamic simulation of a series of changes on the surface of titanium under the combined influence of body fluid and stress in human body environment is carried out. The purpose of this paper is to study the effect of stress on the growth of apatite, and to show that the difference of the growth of this kind of apatite in the design and use of biomaterials may lead to the failure of biomaterials in use. And the reaction at the interface is different from non-stress analysis, which proves that stress is likely to be an important factor in biomaterials research, especially in vitro simulation experiments. It is more likely to be an indispensable factor.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R318.08

【相似文献】