【作者】 时丽；

【导师】 白玉； 张志勇；

【作者基本信息】 内蒙古工业大学 ， 工程硕士（专业学位）， 2019， 硕士

【摘要】 羟基磷灰石（Hydroxyapatite,简称HA）涂层,是目前骨修复和骨替换材料领域的研究热点之一。但随着创伤人数的增加及置换手术患者的年轻化,人们对植入体的要求越来越高。HA涂层在体液中溶解速率过快,植入体内易引发失效,导致骨结合失败;以及抑菌性差,易引发感染、种植体松动等问题,难以满足实际临床需求。由于氟离子（F^-）具有一定的抑菌作用,且半径比羟基（OH^-）的半径小,F^-的掺入导致HA晶格常数变小,晶体稳定性提高,能够降低在人体内的溶解度。另外,目前应用最为广泛的制备HA涂层的方法是大气等离子喷涂,但由于其对粉体要求较高,需进行二次造粒,导致涂层制备成本增加,材料浪费严重。基于此,本论文利用悬浮液等离子喷涂（SPS）技术,在钛基体表面制备了兼具抗溶解性及抗菌性的氟代羟基磷灰石（FHA）生物涂层,这对促进HA生物涂层的发展应用具有重要意义,具体结果如下:（1）本文以化学共沉淀法合成了FHA粉体,制备了满足SPS需要的FHA水基悬浮液,初步探究了分散机理。结果表明,当加入分散剂焦磷酸钠1wt.%时,FHA粉体沉降时间最长,悬浮液的稳定性最高（粘度为2.38 mPa?s,表面张力为52 N/m）。球磨前后,FHA粉体粒径分布始终保持在0.1³0μm之间,但通过增加粉体与分散剂的混合接触,进一步提高了FHA悬浮液的稳定性。（2）利用SPS技术在钛基体表面制备了FHA涂层,考察了不同工艺参数（喷涂距离、雾化压力、喷涂功率）对FHA涂层的显微形貌、成分及组织结构的影响。XRD结果显示,在制备态涂层中除了主晶相HA之外,还包含少量的α-TCP,β-TCP和TTCP等分解相。FT-IR和XPS结果确认了在经过等离子喷涂的高温过程以后F离子仍以取代OH的形式存在于HA晶格中。（3）根据SEM及力学性能分析可知,随着喷涂距离的增加,粉体在等离子体火焰中的熔化效果变差。喷涂距离为40mm时,FHA涂层硬度最大,致密度最高,结合力最好。雾化压力的大小直接影响了进入等离子火焰的液滴大小和速度,进而影响了粉体颗粒的熔化效果。雾化压力为1.25bar时,FHA涂层硬度最大,致密度最高,结合力最好。另外,随着喷涂功率的增大,明显提高了FHA涂层的沉积效率及熔化效果。当喷涂功率达到45kW时,FHA涂层硬度最大,致密度最高,结合力最好。（4）电化学试验结果表明,对于钛基体而言,FHA制备态涂层对基体有较好的保护效果。但不同工艺制备的FHA涂层抗腐蚀性能略有不同,喷涂距离40mm、雾化压力1.25bar、喷涂功率45kW这三种工艺制备的涂层对基体保护效果分别为86.86%、90.32%及81.16%,抗腐蚀性能最佳。（5）溶解性实验结果显示,在柠檬酸修饰的PBS缓冲溶液（pH=4）中,FHA涂层释放的Ca²⁺浓度远远低于HA涂层,表明F离子的掺入,明显提高了HA涂层的抗溶解性。（6）根据体外生物性能测试结果可知,F离子的引入并没有降低HA涂层表面的成骨细胞活性。与HA涂层相比,粘附在FHA涂层表面的金黄色葡萄球菌数目较少,表明FHA涂层具有一定的抗菌性能。总之,SPS技术的工艺参数对涂层形貌、成分、结构及性能有着至关重要的影响。F离子的掺入,导致FHA涂层的抗溶解性、抗菌性等生物性能均优于HA涂层。利用SPS技术制备FHA涂层,有望在人体硬组织替换、修复领域获得广泛应用,对提高人体植入体的寿命具有重要意义。更多还原

【Abstract】 Hydroxyapatite（HA）has a similar chemical structure as that of human bone and teeth.Owing to its excellent biocompatibility,it has been extensively used in many prosthetic applications to improve the direct contact of bone-implants and ultimately minimize the healing time.However,with the increase in the number of traumas and more and more young replacement surgery patients,the requirements for implants are getting higher and higher.The dissolution rate of the HA coating in the body fluid is too fast,and it is easy to cause failure in the implanted body,resulting in failure of bone binding.As well as the coating’s poor antibacterial properties,it is easy to cause infection,implant loosening and other issues,it is difficult to meet the actual clinical needs.Fluoridated hydroxyapatite（FHA）,in which F-partially replaces OH-in the HA structure,is considered an alternative material for bone repair because it exhibits low solubility and good biocompatibility.In addition,The HA coatings are fabricated mostly by atmospheric plasma spraying（APS）process as the process is relatively cheaper and has the ability to coat large areas of complex shapes.However,the conventional plasma spray process requires hydroxyapatite powders with good flowability and to prepare such freely flowing powders,tedious agglomeration processes such as spray drying,fusing and crushing are being used.Suspension plasma spraying saves one step in comparison to conventional plasma spraying as fine particles can be directly sprayed onto the plasma in the form of suspension instead of the agglomerated particles.Therefore,we have prepared FHA coating by suspension plasma spraying.This coating has both anti-solubility and antibacterial properties,which is of great significance for the application of implants.Specific conclusions are as follows:1.The FHA powder was synthesized by chemical coprecipitation method,and the FHA water-based suspension satisfying the SPS requirement was prepared.When the dispersant sodium pyrophosphate was added 1.0%,the FHA powder had the longest settling time and the suspension had the highest stability（viscosity 2.38 mPa?s,surface tension 52 N/m）.2.FHA coatings were prepared on the surface of titanium substrate by SPS technique.The effects of different process parameters（spray distance,atomization pressure,spray power）on the microstructure,composition and microstructure of FHA coating were investigated.The XRD result showed that all coatings contained a HA major phase and the decomposition phases（α-TCP,β-TCP and TTCP）.FT-IR and XPS confirmed the presence of fluorine in the as-sprayed coatings.3.According to the SEM and mechanical properties analysis,as the spraying distance increases,the coating melting effect becomes worse.When the spraying distance is 40mm,the FHA coating has the highest hardness,the highest density and the best bonding force.The atomization pressure directly affects the droplet size of the suspension and entering the plasma flame and velocity,which in turn affects the melting effect of the coating.When the atomization pressure is 1.25 bar,the FHA coating has the highest hardness,the highest density and the best binding force.In addition,as the spraying power increases,the deposition efficiency and melting effect of the FHA coating are significantly improved.When the spraying power reaches 45kW,the FHA coating has the highest hardness,the highest density and the best bonding force.4.The corrosion behavior was studied in a SBF solution using potentiodynamic polarization test,and the results indicated that the coatings enhanced the corrosion resistance of the Ti substrate.The coatings prepared by the three processes of spraying distance of 40 mm,atomization pressure of 1.25 bar and spraying power of 45 kW have the best protection effect on the substrate,which are 80.86%,90.32%and 81.16%,respectively.5.The chemical stability of the FHA coatings was assessed by evaluating the release of Ca²⁺ions.The results indicated that the substitution of fluorine into the hydroxyapatite（HA）structure had a positive effect on the dissolution resistance of the HA.6.The Antibacterial activity revealed that the antibacterial Activity of the FHA coating was greater than that of the pure HA coatings.cell culture tests showed that the FHA Coating did not exhibit cytotoxicity,and the cell proliferation was comparable with That of the HA coatings.In summary,the process parameters in SPS technology have a crucial impact on the morphology,composition,structure and properties of the coating.The FHA coating has good bioresistance such as solubility resistance and antibacterial properties.The preparation of FHA coating by SPS technology is expected to be widely used in the field of hard tissue replacement and repair.更多还原