摘要
多孔Y2SiO5陶瓷具有高熔点、抗氧化、低热导率的特点，在高温隔热领域具有很高的应用价值，其同时兼具低介电和低损耗的特性，具有良好的透波应用潜力，是一种潜在耐高温透波材料。但是目前对多孔Y2SiO5陶瓷的研究相对较少，且在制备过程中存在一定的问题，如采用两步法制备多孔Y2SiO5陶瓷，过程复杂，所得样品孔隙率较低、介电性能研究较少。通过凝胶注模和原位反应烧结工艺制备高气孔率多孔Y2SiO5陶瓷，采用非水基的（N，N-二甲基甲酰胺）DMF基凝胶注模体系，对浆料流变性和稳定性及凝胶化行为进行了研究，通过优化坯体的干燥和排胶工艺，获得了收缩小且形貌完整的多孔坯体，研究了原位反应烧结温度对多孔Y2SiO5陶瓷物相、孔隙率及微观组织结构的影响规律，对所制备的多孔Y2SiO5陶瓷的力学和介电性能进行了表征，最终获得了高气孔率且力/电性能优良的多孔Y2SiO5陶瓷。future什么意思
hd什么意思以氧化硅和氧化钇为原料，采用DMF为溶剂，丙烯酰胺为单体，通过凝胶注模成型工艺制备多孔坯体。通过优化排胶工艺获得了形貌完整的坯体。研究了溶剂种类、分散剂种类、催化剂和引发剂含量对浆料及凝胶行为和坯体完整性的影响。研究结果表明，凝胶注模成型工艺中选用DMF为溶剂，分散剂选用聚丙烯酸（含量为粉体质量的1.6%），引发剂过硫酸铵和催化剂四甲基乙二胺用量分别为单体质量的20%和1%时，可以获得表面光滑完整、没有裂纹、收缩较小的完整坯体。通过TG/DSC对生坯的排胶工艺进
行分析，制订了最佳的排胶工艺为：以0.2℃/min 的升温速率加热到700℃，其中在150℃、380℃、540℃和700℃各保温2h。
研究了烧结温度和固相含量对多孔Y2SiO5陶瓷物相、孔隙率、及孔径分布和微观组织结构的影响。研究发现，当烧结温度低于1450℃时，所制备的多孔Y2SiO5陶瓷中含有未反应的氧化硅和氧化钇。高于此温度时，可以获得纯相的多孔Y2SiO5陶瓷。通过控制烧结温度和固相含量可以实现对孔隙率和孔径分布的调节，随着烧结温度的升高，多孔Y2SiO5陶瓷的烧结收缩率增加、孔隙率下降、孔径尺寸减小，烧结温度一定时，随着固相含量的增加，多孔Y2SiO5陶瓷的烧结收缩率下降、孔隙率下降、孔径尺寸减小。依调节烧结温度和固相含量的不同，所制备的多孔Y2SiO5陶瓷的孔隙率分布在64.59-81.00%的范围，平均孔径大小在1-2.3µm范围。当烧结温度为1450℃时，固相含量为10%时，所制备的多孔Y2SiO5陶瓷可以获得
最高孔隙率为81.00%。
对所制备的多孔Y2SiO5陶瓷的力学和介电性能进行了表征。结果表明：在力学性能方面，依调节固相含量和烧结温度的不同，所制备的多孔Y2SiO5陶瓷的压缩强度在1.12-18.84MPa范围内，当固相含量为20%，烧结温度为1500℃时，多孔Y2SiO5陶瓷的压缩强度最高为18.84MPa；在高温稳定性方面，
专升本第一学历本论文所制备的多孔Y2SiO5陶瓷经过高温处理后，试样的孔隙率、孔径大小以及物相组成均没有发生明显改变；在介电性能方面，随着孔隙率从81.00%下降到64.59%，多孔Y2SiO5陶瓷的介电常数从1.78增加到2.49，当在1500℃烧结，固相含量为10%的多孔Y2SiO5陶瓷具有最低的介电常数为1.78。
关键词：多孔Y2SiO5陶瓷；DMF基凝胶注模；压缩强度；介电性能
Abstract
Porous ceramics with high porosity,low density,low dielectric constant and low thermal conductivity is finding wider and wider application in the field of heat insulation and air wave.However there are relatively few studies on porous Y2SiO5 ceramics，and there are some problems in the preparation process.If the porous Y2SiO5 ceramics are prepared by two-step method,the process ia complicated and the porosity of the obtained samples is low and the dielectric properties are less.Preparation of high porosity porous Y2SiO5ceramics by gel-casting,(N,N-dimethyl formamide)DMF-bad gel-casting system was ud tostudy the rheological and stability and gelation behavior of the slurry,By optimizing the drying and discharging process of the green body,the porous body with small shrinkage and complete appearance,The effects of the in situ reaction sintering temperature on the p
orous Y2SiO5ceramic pha and the microstructure of the porous Y2SiO5ceramics were characterized.The mechanical properties and dielectric properties of the prepared porous Y2SiO5ceramics were characterized.Finally,porous Y2SiO5ceramics with high porosity and excellent force/electrical properties were obtained.
SiO2and Y2O3as raw materials,using DMF ass solvent,acrylamide as monomer, through the gel-casting preparation of porous body.Through the optimization of the discharge process to obtain a complete shape of the body.The effects of solvent type, dispersant type,catalyst and initiator content on slurry and gel behavior and bulk integrity were studied.The results showed that DMF was ud as the solvent in the gel-casting,and the polyacrylic acid(1.6%of the powder content)was ud as the dispersant.The amount of the initiator ammonium persulfate and the catalyst tetramethylethylenediamine was monomer20%of the quality and1%,you can get the surface smooth and complete,no cracks,shrink the smaller integrity of the body.The optimum dyeing process was carried out by TG/DSC.The optimum conditions were as follows:heating to700℃at a heating rate of0.2℃/min,and insulation for2h at150℃, 380℃,540℃and700℃.
The effects of sintering temperature and solid content on the pha,porosity,pore size distribution and microstructure of porous Y2SiO5ceramics were studied.It was found that when the sintering tem
perature was lower than1450℃,the prepared porous Y2SiO5ceramics contained unreacted silica and yttrium oxide.Above this temperature, pure pha porous Y2SiO5ceramics can be obtained.By adjusting the sintering temperature and solid content,the porosity and pore size can be adjusted.With the
25 ceramics increas,the porosity decreas,the pore size decreas,and the sintering temperature decreas.With the increa of solid content,the sintering shrinkage rate of porous Y2SiO5ceramics decread,the porosity decread and the pore size decread. The porosity of the prepared porous Y2SiO5ceramics is in the range of64.59-81.00% and the average pore size is in the range of1-2.3μm according to the different sintering temperature and solid content.When the solid content is10%and the sintering temperature is1450℃,the prepared porous Y2SiO5ceramics can obtain the highest porosity of81.00%.
The mechanical and dielectric properties of the prepared porous Y2SiO5ceramics were characterized.The results show that the compressive strength of the prepared Y2SiO5ceramic is in the range of1.12-18.84MPa,and when the solid content is20% and the sintering temperature is1500
℃,the compressive strength of the prepared porous Y2SiO5is in the range of1.12-18.84MPa.,The maximum compressive strength of porous Y2SiO5ceramics is18.84MPa.In the high temperature stability,the porosity, pore size and pha composition of the porous Y2SiO5ceramics prepared by this paper have not changed obviously after high temperature treatment.The dielectric constant of the porous Y2SiO5ceramics incread from1.78to2.49with the porosity decreasing from81.00%to64.59%.When the porosity was sintered at1500℃,the porous Y2SiO5 ceramics with the solid content of10%had the lowest electrical constant of1.78. Keywords:Porous Y2SiO5ceramics;DMF-bad gel-casting;compression strength;
dielectric properties
目录
摘要............................................................................................................................III 第1章绪论.. (1)
1.1课题背景 (1)祝你生日快乐英文
1.2Y2SiO5概述 (2)
四级英语培训1.2.1Y2SiO5的晶体结构 (2)
1.2.2Y2SiO5的性能 (2)
1.2.3Y2SiO5的合成 (4)
1.3多孔陶瓷的制备方法 (5)
1.3.1造孔剂法 (5)
北卡罗来纳州立大学1.3.2挤压成型法 (6)
1.3.3发泡法 (6)
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1.3.4颗粒堆积法 (6)
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1.3.5有机泡沫浸渍法 (7)
1.3.6冷冻干燥法 (7)
1.3.7溶胶-凝胶法 (8)
1.3.8凝胶注模法 (8)
1.3.9多孔陶瓷制备方法的对比分析 (10)
1.4多孔Y2SiO5陶瓷的研究现状 (10)
1.5研究目的、意义和内容 (13)
第2章试验材料与研究方法 (15)
2.1试验原料 (15)
2.2多孔Y2SiO5陶瓷的凝胶注模工艺 (16)
2.3材料性能测试方法 (19)
2.3.1原料粉体粒径表征 (19)
2.3.2浆料的剪切粘度 (19)
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2.3.3TG/DSC分析 (19)
2.3.4孔隙率和体积密度 (19)
2.3.5孔径分布 (20)
