【作者】 王卫卫；

【导师】 张显； 曾庆丰；

【作者基本信息】 西安电子科技大学 ， 工程硕士（专业学位）， 2019， 硕士

【摘要】 氧化锆生物陶瓷具有良好的生物相容性,与羟基磷灰石、磷酸钙为代表的生物陶瓷材料相比,其具有优越的机械性能。3D打印方法具有独特的优势,能够对材料的外形和内部孔隙结构进行设计,从而为患者个性化设计骨修复支架。但是3D打印方法所设计的孔径均为宏孔结构,无法对微孔结构进行设计。造孔剂法是常用于制备微孔结构的方法,造孔剂法制备多孔陶瓷的优势在于可以往陶瓷中引入大量孔隙,缺点是连通率低。本文将3D打印方法与造孔剂法相结合制备出具有宏孔/微孔结构的多孔氧化锆生物陶瓷。以去离子水作为溶剂,添加分散剂、粘结剂和增塑剂,通过对浆料的粘度和稳定性的测试与分析,获得满足3D打印要求的陶瓷浆料。研究了坯体干燥和排胶工艺,获得形貌完整的陶瓷坯体。研究了烧结温度对氧化锆陶瓷物相、相对密度、孔隙率和显微形貌的影响。通过添加淀粉作为造孔剂制备出具有宏孔/微孔结构的多孔氧化锆陶瓷,并对其进行表征与分析,最终获得高气孔率和高强度的多孔氧化锆生物陶瓷。主要研究结果如下:(1)实验中以3mol%钇稳定氧化锆为原料,采用柠檬酸作为分散剂,聚乙烯醇作为粘结剂,聚乙二醇作为增塑剂。通过3D打印方法成型出宏孔结构的坯体。通过优化干燥、排胶工艺获得完整的坯体。研究了分散剂种类及含量,粘结剂、固含量和增塑剂含量对氧化锆陶瓷浆料的影响。研究结果表明,当柠檬酸含量为0.4 wt.%、聚乙烯醇含量为0.6 wt.%、聚乙二醇含量为0.25 wt.%、固含量为44 vol%时制备出的氧化锆陶瓷浆料具有良好的稳定性和较低的粘度。在3D打印方法挤出过程中,浆料呈丝状均匀挤出,未出现断裂。坯体排胶制度确定为:从25℃~200℃升温速率为3℃/min,从200℃升温到600℃,升温速率为1℃/min并在600℃保温2 h。(2)研究了烧结温度对多孔氧化锆陶瓷物相、体积密度、相对密度、孔隙率、收缩率以及显微形貌的影响。研究发现,烧结温度从1400℃升高到1500℃,四方相含量逐渐增多而单斜相减少。当烧结温度在1550℃时,单斜相相对增加,但增加量较少。随着烧结温的升高,氧化锆陶瓷的体积密度、相对密度和收缩率都逐渐增大,气孔率逐渐减小。当烧结温度为1500℃时,陶瓷体积密度为5.93 g/cm~3,相对密度为97.2%。收缩率为18.3%,气孔率为2.78%,烧结温度升高至1550℃,其变化量较小。氧化锆陶瓷样品随烧结温度的升高,晶粒分布均匀,气孔尺寸逐渐缩小,但是当烧结温度为1550℃时,大晶粒数量显著增加,过烧现象尤为明显。烧结温度在1500℃时,烧结效果较好。(3)研究了淀粉不同添加量对氧化锆陶瓷体积密度、孔隙率、收缩率及孔径分布的影响,同时对其力学性能和显微形貌进行表征。结果表明,淀粉添加量从10 wt.%增加到50 wt.%,烧结出的多孔氧化锆陶瓷孔隙率与收缩率逐渐增加,体积密度逐渐降低。当淀粉添加量达到50 wt.%时,多孔陶瓷的孔隙率达到57.03%,体积密度为2.62 g/cm~3,收缩率为23.82%,其抗弯强度可以达到14.5 MPa。制备出的多孔氧化锆陶瓷气孔分布均匀,孔径尺寸均与淀粉粒径相当。通过对淀粉添加量的控制可以实现对氧化锆陶瓷中微孔的孔隙率和孔径分布的有效调控,制备出具有孔隙可设计的宏孔与微孔结构的多孔氧化锆生物陶瓷。更多还原

【Abstract】 Zirconia bioceramics have good biocompatibility and superior mechanical properties compared with hydroxyapatite and calcium phosphate bioceramics.The 3D printing method has unique advantages in that it is able to design the shape and internal pore structure of the material,so as to design personalized bone repair scaffolds for patients.However,the pore sizes designed by this method are all macroporous structures,it is impossible to design microporous structures.Pore-forming method is often used to prepare microporous structure.The advantage of pore-forming method in preparing porous ceramics is that it can introduce a large number of pores into the ceramics,but the disadvantage is that the connectivity rate is low.With deionized water as the solvent,dispersant,binder and plasticizer were added.Through the test and analysis of viscosity and stability of the slurry,the ceramic slurry meeting the requirements of 3D printing was obtained.The drying and debinding process of the green body was studied,and a ceramic body with complete morphology was obtained.The effects of sintering temperature on the phase,relative density,porosity and microstructure of zirconia ceramics were investigated.The porous zirconia ceramic with macroporous/microporous structure prepared by adding starch as a pore-forming agent,and it was characterized and analyzed.Finally a porous zirconia bioceramic with high porosity and high strength was obtained.The main findings are as follows:(1)In the experiment,3 mol%of yttria-stabilized zirconia was used as a raw material,citric acid was used as a dispersant,polyvinyl alcohol was used as a binder,and polyethylene glycol was used as a plasticizer.The green body of the macroporous structure was formed by a 3D printing method.A complete blank was obtained by optimizing the drying and debinding process.The effects of the type and content of dispersant,binder,solid content and plasticizer content on zirconia ceramic slurry were studied.The results showed that the zirconia ceramic slurry prepared with citric acid content of 0.4 wt.%,polyvinyl alcohol content of 0.6 wt.%,polyethylene glycol content of 0.25 wt.%,and solid content of 44 vol%had better stability and lower viscosity.During the extrusion of the slurry in the 3D printing process,the slurry was uniformly extruded in a filament form without cracking.The debinding system was formulated as follows:from 25℃to 200℃,the heating rate was 3℃/min,from 200℃to 600℃,the heating rate was 1℃/min and held at 600℃for 2 h.(2)The effects of sintering temperature on the phase,bulk density,relative density,porosity,shrinkage and microstructure of porous zirconia ceramics were investigated.The results showed that the sintering temperature increased from 1400℃to 1500℃,the tetragonal phase content increased and the monoclinic phase decreased.When the sintering temperature was at 1550℃,the monoclinic phase was relatively increased,but the amount of increase was small.With the increase of sintering temperature,the bulk density,relative density and shrinkage of zirconia ceramics gradually increased,and the porosity decreased.When the sintering temperature was 1500℃,the ceramic bulk density was 5.93 g/cm~3 and the relative density was 97.2%.The shrinkage rate was 18.3%,the porosity was 2.78%,and the sintering temperature was increased to 1550℃,and the amounts of change were small.With the increase of sintering temperature,the zirconia ceramic samples had uniform grain distribution and narrow pores.However,when the sintering temperature was at 1550°C,the number of large crystal grains increased remarkably,and the over-burning phenomenon was particularly obvious.When the sintering temperature was at 1500°C,the sintering effect was better.(3)The effects of different starch additions on the bulk density,porosity,shrinkage and pore size distribution of zirconia ceramics were investigated,and their mechanical properties and microstructure were characterized.The results showed that the amount of starch added increased from 10 wt.%to 50 wt.%,and the porosity of the sintered porous zirconia ceramics increased gradually,the bulk density decreased,and the shrinkage rate gradually increased.When the amount of starch added reached 50 wt.%,the porosity of the porous ceramic reached 57.03%,the bulk density was 2.62 g/cm~3,the shrinkage rate was23.82%,and the flexural strength can reach 14.5 MPa.The prepared porous zirconia ceramic had a uniform pore distribution and the pore size was equivalent to the starch particle size.By controlling the amount of starch added,the microporous porosity and pore size distribution of zirconia ceramics can be effectively controlled,and porous zirconia bioceramics with macroporous and microporous structures with pore design can be prepared.更多还原