【作者】 王毅；

【导师】 陈传忠；

【作者基本信息】 山东大学 ， 材料学， 2016， 硕士

【摘要】 钛及钛合金具有较好的生物相容性、耐腐蚀性和生物学稳定性,被视为理想的生物医用材料,应用前景非常广阔。但钛合金作为植入体生物活性较差,与机体结合强度低,愈合时间长。为了提高钛及钛合金的生物活性,促进其与生物骨组织的化学键合,目前常用的方法是在金属材料表面进行生物活化改性处理。在众多表面改性技术中,微弧氧化技术能够制备多孔结构、结合力强且具有生物活性的陶瓷膜层,备受关注。通常,微弧氧化表面制备HA都需要后续水热处理或碱热处理,直接通过微弧氧化制备HA的研究很少。本试验试图通过对微弧氧化电解液进行设计,直接在纯钛表面原位生成HA膜层。本文主要从以下几方面对纯钛表面微弧氧化膜层进行研究。以乙酸钙(CH3COO)2Ca)为钙源,以磷酸氢二钠(Na2HP04)、六偏磷酸钠((NaPO3)6)、磷酸钠(Na3PO4)及甘油磷酸二钠(C3H4Na2O6P-5H2O)四种不同的磷酸盐为磷盐,设计不同钙磷比的12组电解液成分,进行微弧氧化处理,探究不同钙磷体系下微弧氧化膜层的组织结构及生物活性,以实现对电解液的优化,该电解液成分将做为后续颗粒优化微弧氧化膜层制备的基础电解液。随后,探究CaHPO4·2H2O和Ca10(PO4)6(OH)2颗粒加入以及加入量对微弧氧化膜层组织结构及生物活性的影响。使用X射线衍射仪(XRD)、扫描显微镜(SEM)、傅里叶红外光谱仪(FT-IR)及电化学工作站表征不同电解液制备的微弧氧化膜层的组织结构及物理化学性能。通过在模拟体液(SBF)中进行仿生沉积,使用SEM,EDS,XRD及FT-IR测定膜层诱导生成羟基磷灰石能力,以评价其体外生物活性。试验结果表明,仅通过微弧氧化技术可在纯钛表面原位生成含氟羟基磷灰石(Ca10(PO4)6(OH)2-xFx)的生物膜层。以(CH3COO)2Ca 为钙盐,以 Na2HP04 和Na(P03)6为磷盐,钙磷比为3:1时,在纯钛表原位可生成(Ca10(PO4)6(OH)2-xFx)磷灰石膜层,所制备的膜层具有较高的钙磷含量,且在模拟体液中诱导生成磷灰石能力较强。在SBF中浸泡7天后,微弧氧化孔洞内团聚沉积成直径为6μm的微球,且小球周围有明显的鳞片状磷灰石层。膜层厚度随磷盐浓度的增加而不断增加。膜层主要组成相有Anatate,Rutile,CaF2和CaTi03,含氟相主要在微弧氧化后期出现。以C3H7Na2O6P·5H2O为磷盐的膜层并不具有很好的生物活性,在SBF中诱导生成HA能力较差,经模拟液体浸泡后保持了原有形貌,耐蚀性较强,腐蚀电流优于其它膜层三个数量级。FT-IR说明在模拟体液浸泡过程中膜层中的HA发生溶解或转化,生成Ca5F(PO4)3,浸泡后结构O-H消失。加入颗粒优化后各膜层表面更为平整。加入CaHPO4·2H2O制备的膜层最为平整光滑。膜层厚度在37-43μm范围之间,膜层厚度相差不大,说明颗粒加入并没有影响电解液的导电率和微弧氧化成膜速率。CaHPO4·2H2O和HA的加入不会改变微弧氧化膜层的相组成,区别是优化后基本没有基体Ti的峰。加入CaHPO4·2H2O的膜层中并未发现CaHPO4·2H2O相,说明CaHPO4·2H2O并不是以颗粒状进入膜层,而是参与了化学反应,生成羟基磷灰石。超声波空化作用能有效地提高电解液的分散度,电解液分散度增强,有利于微弧氧化反应更加均匀。在SBF浸泡试验中,添加不同的颗粒以及添加量对诱导生成的磷灰石能力都有影响。添加CaHPO4·2H2O时,膜层形成弥散分布的细小颗粒,同时也有弥散微球生成;添加HA时,膜层形成疏松的层状磷灰石。颗粒添加量较大时诱导生成磷灰石能力更强。添加CaHPO4·2H2O所形成的膜层较添加HA形成的膜层耐蚀性更高,当CaHPO4·2H2O加入量为4g/L时,膜层耐腐蚀性能明显提高。通过试验,推测微弧氧化在模拟体液中诱导生成羟基磷灰石的形成机制,可能是膜层表面形成了大量的Ti-OH功能团,与溶液中的Ca2+和PO43-反应,促进了磷灰石的形核生长。更多还原

【Abstract】 Titanium and its alloys are expected to be ideal materials for medical application because of its biocompatibility,high corrosion resistance and bio-stability.However,unlike bioactive ceramics,bio-glass,hydroxyapatite(HA),titanium implants have low bioactive and cannot bond directly to the bone.Various surface modification approaches have been used for biological properties improvement.Among various surface modification techniques,micro-arc oxidation(MAO),which can produce porous,adhesive and bioactive coatings,has aroused considerable attention.Generally,the titanium oxide layer can further crystallized into HA through a hydrothermal treatment or alkali heat-treatment.Few studies prepared HA coating by micro-arc directly.In this study,we aim to prepare HA containing coatings on titanium by adjusting the electrolytes.In this study,calcium acetate(CH3COO)2Ca)as the calcium compound,disodium hydrogen phosphate(Na2HPO4),sodium hexametaphosphate((NaPO3)6),sodium phosphate(Na3PO4),disodium glycerophosphate(C3H4Na2O6P-5H2O)four different phosphate salts as phosphate compounds,which were chosen to prepare 12different groups electrolytes.The microstructure,corrosion resistance and biological activity were studied.An optimization electrolyte will be used as the basis electrolyte for further study.Then,explore the influence of particles adding(CaHP04-2H2O and Ca10(PO4)6(OH)2)on the MAO coating properties.Structure,physical and chemical properties of MAO coatings prepared by different electrolytes are characterized by X-ray diffraction(XRD),scanning electron microscope(SEM),Fourier transform infrared spectroscopy(FT-IR)and electrochemical characterization workstation.The apatite inducing property in SBF is characterized by using SEM,EDS,XRD and FT-IR.The results showed that only by micro-arc oxidation technology directly can prepared(Ca1o(PO4)6(OH)2-XFX))containing coatings.When(CH3COO)2Ca as the calcium salt,Na2HPO4 and(NaPO3)6 as a phosphate salt,calcium and phosphorus ratio of 3:1,apatite coatings can be prepared directly.The coatings have a high content of calcium and phosphorus,and have a good ability in apatite inducing in SBF for 7 days.Round-shapes deposition with a diameter of microspheres of 6 μm can be observed in micro-holesl.Thickness increases with the increasing of phosphorus concentration.The main phases are Anatate,Rutile,CaF2 and CaTiO3,and the fluorine-containing phase appeared in the late period of micro-arc oxidation process.C3H7Na2O6P·5H2O does not have good biological activity in SBF.Though biological active is bad,the corrosion resistance of C4 is strong.The corrosion current was better than others by three orders of magnitude.There was a dissolution or transition of HA when the coatings are immersed in SBF.The addictive of particles can make the MAO coating smooth.CaHPO4·2H2O-doped coatings are smoothest.Thickness is in the range of 37 to 43μm.So particles have no effects on conductivity of the electrolyte.CaHPO4.2H2O and HA-doping do not change the phase composition,but the peak of Ti became weak.There was no CaHPO4-2H2O in the coatings,which indicating that CaHPO4·2H2O did not enter the granular coatings,but involved in chemical reactions.Ultrasonic cavitation can effectively improve the dispersion of the electrolytes,and the electrolytes dispersion can in favor of the uniform of the coatings.In the SBF immersion test,particle-doping has an impact on the capacity of inducing apatite.When CaHPO4·2H2O adding,there fine particles dispersed on the coating after immersion in SBF;when HA adding,there loose apatite dispersed on the coating after immersion in SBF.Larger amount of particles adding can induce apatite stronger.CaHPO4-2H2O-doped coatings have better corrosion resistance than that the HA-doped coatings.When the amount of CaHPO4·2H2O was 4g/L,the corrosion resistance of the coating could significantly be improved.The reseaon for apatite-forming ability in SBF is that abundant Ti-OH groups were formed on the surfaces of the coatings during the SBF immersion process.Ti-OH reacts with the Ca2+ and PO43-,promoting the growth of the nucleation of apatite.更多还原