织构PNN-PZT陶瓷的光固化成型制备及其电学性能研究

为高效制备织构压电陶瓷,以球状Pb(Ni_1/3Nb_2/3)O₃-PbZrO₃-PbTiO₃ (PNN-PZT) 为基体粉体,片状BaTiO₃ （BT）为模板粉体,采用光固化成型技术代替传统流延技术制备织构压电陶瓷。研究了粉体形貌对打印浆料流动性的影响、浆料的光敏参数以及不同BT含量织构陶瓷的晶体结构和电学性能。结果表明,球状粉体浆料具有低黏度的特性,能够有效提高打印浆料的固含量,最大固含量可达86%（质量）。此时陶瓷浆料的临界曝光量与透射深度分别为127.5 mJ/cm²和21.1 μm。打印后的PNN-PZT-BT陶瓷沿[00l]_c方向生长,BT模板粉体含量从1%增长到5%,陶瓷的织构度由42%增到92%。当BT含量为3%时,样品具有最高的压电常数d₃₃=1047 pC/N。与传统的流延法相比,SLA技术的工艺优势在于制备周期短,稳定性高,能够有效降低织构陶瓷的制备难度。     

铌酸钾钠无铅压电陶瓷水系流延浆料的工艺研究

模版晶粒生长技术制备织构化铌酸钾钠无铅压电陶瓷是提高其压电性能的重要途径,为了获得较高的织构度,水系流延浆料的制备是关键技术.本研究以固相法合成的铌酸钾钠粉体和片状Nb2O5模板晶粒为固含量,以去离子水为溶剂,研究不同含量的分散剂、粘结剂和增塑剂对流延浆料性能的影响.研究结果表明,当粉体固含量为55wt％,分散剂PVP含量为5.5wt％,粘结剂苯丙乳液含量13.5wt％,增塑剂丙三醇含量为5.5wt％时,制备的流延浆料粘度适中,流延后可制得表面光滑、质地均匀、塑性较好、可任意卷曲的流延膜片.     

硅烷偶联剂对氧化铝陶瓷浆料流动性能和3D打印性能的影响

基于光固化3D打印技术需要高固相含量、低黏度的陶瓷浆料以防止烧结陶瓷部件产生裂纹、孔洞、翘曲等缺陷,通过测试流变性能与固化性能,本文优化了树脂单体的选用及配比,采用KH550、KH560、KH570三种硅烷偶联剂对Al₂O₃粉体表面改性,以改善陶瓷浆料的流变性能和稳定性,探讨了硅烷偶联剂降低Al₂O₃陶瓷浆料体系黏度的机理,获得了固相含量为75%(质量分数)(体积分数为45.5%)、黏度为4 540 mPa·s的Al₂O₃陶瓷浆料,并提出了一种光固化Al₂O₃陶瓷浆料制备的优化方法,这有望对用于制备复杂陶瓷的高固含量、低黏度的3D打印Al₂O₃陶瓷浆料提供帮助。     

国内工业陶瓷文献题录及文摘（四十一）

流延法制备铌酸钾钠无铅压电陶瓷的工艺研究·陶瓷学报,2011,01以Na2CO3,K2CO3,Nb2O5等为原料,采用固相法合成了K0.5Na0.5NbO3的粉体,并以此粉体为主要原料,添加适量的分散剂、粘结剂及除泡剂制备浆料,采用流延法制备K0.5Na0.5NbO3膜片,研究了K0.5Na0.5NbO3固相含量、分散剂、粘结剂及除泡剂的种类及含量对流延浆料流延性能和对K0.5Na0.5NbO3陶瓷的影响。     

光固化氧化铝陶瓷浆料流变性能研究进展

立体光固化成型技术是一种生产高精度、高性能陶瓷部件的新兴增材制造工艺。制备具有良好流动性和高固相含量的陶瓷浆料是立体光固化增材制造工艺的优势。本文讨论了固相含量、单体、分散剂、粉体级配等因素对浆料流变性能的影响规律,总结了目前配制高固相含量和低黏度光固化Al₂O₃陶瓷浆料的材料选择原则,归纳了制备高固相含量、低黏度Al₂O₃陶瓷浆料的指导方法,指出了高性能光固化Al₂O₃陶瓷浆料开发的主要趋势和面临的挑战。     

流延法制备铌酸钾钠无铅压电陶瓷的工艺研究

以Na2CO3,K2CO3,Nb2O5等为原料,采用固相法合成了K0.5Na0.5NbO3的粉体,并以此粉体为主要原料,添加适量的分散剂、粘结剂及除泡剂制备浆料,采用流延法制备K0.5Na0.5NbO3膜片,研究了K0.5Na0.5NbO3固相含量、分散剂、粘结剂及除泡剂的种类及含量对流延浆料流延性能和对K0.5Na0.5NbO3陶瓷的影响。实验结果表明:流延膜的厚度在0.3mm时,选用三乙醇胺作分散剂效果最好,当固相含量在55wt%时,分散剂用量在2%时浆料的粘度为2000mPa.s,适合于流延工艺;粘结剂PVB的含量在8%时膜片强度较高。     

3D打印氧化硅陶瓷的制备及性能研究

随着陶瓷3D打印技术的发展,3D打印高性能陶瓷越来越受关注,在航空航天领域得到快速应用.通过研究分散剂、浆料pH、氧化硅粉体粒径和固相含量对浆料粘度和流动性的影响,可制备出粘度低、固相含量高、流动性好的陶瓷浆料.测试了不同固相含量对SiO2陶瓷的弯曲强度、烧成收缩率、气孔率和致密度的影响.结果表明:在68vol%的固相含量条件下,烧结后SiO2陶瓷的致密度达到74.32%,烧成收缩率为0.95%.     

锆钛酸钡钙(BCTZx)无铅压电陶瓷的制备及性能研究

采用固相反应法制备不同锆含量的锆钛酸钡钙（BCTZ_x）的粉体,然后通过常压固相烧结制备BCTZ_x陶瓷。利用扫描电子显微镜,X衍射分析仪,压电与介电测试仪测量粉体及陶瓷的形貌、相结构及电学性能。结果表明,在研究涉及的不同锆掺量内,体系均为单一的立方相结构,掺杂没有引起结构相的改变;BCTZ_0.05陶瓷样品的致密度最大,压电常数最大为194 pC/N;BCTZ_0.15陶瓷样品的相对介电常数最大为7367,介电损耗最小为0.012。     

光固化3D打印制备莫来石纤维基多孔陶瓷

传统的成型技术已经无法满足各行业对高精度、复杂结构莫来石纤维基多孔陶瓷的需求，光固化3D打印技术可以直接制得近净尺寸的陶瓷材料，是制备复杂结构陶瓷的理想技术。以莫来石纤维(基体)和纳米SiO₂粉(高温黏结剂)为主要原料，采用光固化3D打印技术成功制备了莫来石纤维基多孔陶瓷。研究了纳米SiO₂粉加入量(加入质量分数分别为0、20%、27%、33%和38%)对纤维浆料的分散稳定性、流变特性和光敏性能的影响，以及对莫来石纤维基多孔陶瓷的显微结构和物理性能的影响。结果表明：SiO₂粉使纤维浆料的黏度显著提升，这有助于缓解纤维的沉降、团聚，获得均匀的打印浆料；但过量的SiO₂粉将导致浆料黏度过大，不利于3D打印过程顺利进行。当SiO₂粉加入量为33%(w)时，纤维浆料的性能最适合3D打印，其在1 h内的沉降率小于9.7%,黏度为3.95 Pa·s(剪切速率为30 s^-1);采用上述浆料打印的莫来石纤维基多孔陶瓷表现出最佳的物理性能(体积密度为0.56 g·cm     

分散剂对低温共烧陶瓷流延浆料流变性能的影响

本文探究了蓖麻油、BYK-22552、聚乙烯吡咯烷酮(PVP)、TEGO-700四种分散剂对CaO-B₂O₃-La₂O₃玻璃/氧化铝低温共烧陶瓷(LTCC)流延浆料分散性的影响,并进一步对该体系浆料流变性能、触变性能、固相体积分数以及沉降性能方面进行了研究,通过红外光谱分析研究了四种分散剂的分散机理并给出了解释。结果表明,当分散剂TEGO-700用量为粉体质量的2%时,流延浆料具有最小黏度(1 650 mPa·s)与最佳触变恢复性。在流延成型最佳黏度2 000 mPa·s下,浆料具有最大固相体积分数(37.2%)与优异的沉降性能。该浆料流延成型得到的柔性生瓷带表面平整且厚度均一,表面粗糙度为144 nm。烧结得到的基板材料表面无气孔、裂纹等明显缺陷,烧结致密化程度高,表面粗糙度为210 nm,40 GHz下测得介电常数与介电损耗分别为6.257和1.431×10^-3。     

Effect of different templates on microstructure of textured Na0.5Bi0.5TiO3–BaTiO3 ceramics with RTGG method

One-dimensional needle-like KSr₂Nb₅O₁₅ (KSN) and two-dimensional plate-like Bi_2.5Na_3.5Nb₅O₁₈ (BNN) particles were used as templates to fabricate grain-oriented Na_0.5Bi_0.5TiO₃–BaTiO₃ (NBTBT) ceramics by reactive-templated grain growth. The effects of the template concentration on the microstructure and orientation of NBTBT ceramics were investigated, and the mechanism of grain growth was discussed. The results show that NBTBT textured ceramics cannot be obtained with KSN template, since the needle-like KSN particles were aligned randomly along the tape casting direction. Ceramics contain perovskite NBTBT and tungsten–bronze-type KSN phase. Some cucurbit-like KSN grains resulted from the defects of needle-like KSN templates were detected. Textured ceramics with orientation factor more than 60% were obtained successfully when the plate-like BNN was used as templates. The results show that the texture fraction of NBTBT textured ceramics increase with increasing the content of BNN. The textured ceramics exhibited {h 0 0} preferred orientation have brick wall microstructure with strip-like grains aligning in the same plane as the casting plane. The reaction and crystal formation of textured NBTBT ceramics with plate-like BNN templates are by diffusion–recrystallization process. Finally the selecting rules of suitable templates are proposed.     

均一球形BaTiO3超细粉体的制备技术

BaTiO₃材料因具有高介电常数及铁电、压电等特性广泛用于功能陶瓷等领域外，还因其具有高白度、高反射率等特点而在生物医药及干式诊断等领域也存在着潜在应用。本文介绍了均一粒径的球形BaTiO₃超细粉体的制备技术，简述了水热法、溶胶-凝胶法、沉淀法等制备技术的优势与不足，并对近年来兴起的新合成方法——传统湿化学联用法、新技术-湿化学联用法、全新湿化学合成法作了简要论述。具有操作简便、工艺简单、原料低廉易得等优势的沉淀法仍具有工业化发展前景，在此基础上的超重力沉淀制备技术可得到球形BaTiO₃超细粉体，利于后续工业化生产；而微通道技术有望制备得球形BaTiO₃超细粉体，其发展前景可观。对于新技术合成BaTiO₃机理还需深入研究；目前对均一球形BaTiO₃超细粉体的研究大多处于实验室小规模生产，其工业放大生产所需合成装置有待进一步探索。     

X8R型BaTiO3基细晶陶瓷的制备、结构和性能

由于在-55~150 ℃存在正交-四方和四方-立方相变,相变对应的尖锐介电峰使BaTiO₃陶瓷介电性能难以满足X8R温度稳定性要求。本文采用50 nm的纳米BaTiO₃粉体和少量堇青石(MgO-Al₂O₃-SiO₂, MAS)玻璃,制备了满足X8R介电温度特性的BaTiO₃基细晶陶瓷。结果表明,随着MAS玻璃的加入,BaTiO₃基陶瓷的室温晶体结构从四方相转变成赝立方相,平均晶粒尺寸从纯BaTiO₃陶瓷的1.904 μm显著降低到添加0.5%(质量分数)MAS玻璃的BaTiO₃基陶瓷的183 nm。与此同时,BaTiO₃基陶瓷虽然介电常数有所下降,但是介电损耗和介电性能的温度稳定性大幅度改善。其中添加0.5%MAS玻璃的BaTiO₃基细晶陶瓷介电性能为:在1 kHz时室温介电常数为984,介电损耗为0.006 5,满足X8R温度特性要求。     

Direct writing of textured ceramics using anisotropic nozzles

Direct writing is a unique means to align anisotropic particles for the fabrication of textured ceramics by templated grain growth (TGG). We show that alignment of tabular barium titanate (BT) template particles (20–40 μm width and 0.5–2 μm thickness) in a PIN-PMN-PT matrix powder (d₅₀ = 280 nm) is significantly improved during direct writing using anisotropic nozzles at high printing rates. The particle orientation distribution in as-printed filaments, and the texture orientation distribution in sintered ceramic filaments are shown to directly correlate with COMSOL Multiphysics-predicted torque distributions for direct writing with aspect ratio 2, 3 and 5 oval nozzles. Electromechanical strain properties of the textured piezoelectric ceramics significantly improved relative to random ceramics when printed with anisotropic nozzles. Simulations of aspect ratio 20 nozzles and nozzles with interior baffles demonstrate significantly increased torque and near elimination of constant shear stress cores (i.e. plug flow).     

Textured PMN–PT and PMN–PZT

A promising way to improve the performance of piezoelectric ceramics is grain orientation by templated grain growth. In this work lead-based piezoelectric ceramics Pb(Mg_1/3Nb_2/3)_0.68Ti_0.32O₃ (PMN–32PT) and Pb(Mg_1/3Nb_2/3)_0.42(Ti_0.638Zr_0.362)_0.58O₃ (PMN–37PT–21PZ) ceramics were textured via templated grain growth process. For texturization (001)-oriented BaTiO₃ (BT) platelets (approximately 10 μm × 10 μm × 2 μm) were utilized as templates. The texturized ceramics were accomplished by aligning the templates by tape casting. The template growth into the matrix resulted in textured ceramics with Lotgering factors between 0.94 and 0.99 for both compositions. Consequences of the texture are enhanced dielectric and piezoelectric properties. Unipolar strain-field measurements of textured ceramics showed 0.25% strain s ₃₃ at 3 kV/mm. Large signal d ₃₃^* of up to 878 pm/V were determined directly from strain measurements. Compared with randomly oriented ceramics in texturized samples unipolar strain s ₃₃ and large signal d ₃₃^* was enhanced by a factor of up to 1.8.     

Effect of polyethylene glycol on the microstructure and PTCR characteristics of n-BaTiO3 ceramics

Porous BaTiO₃ (n-BaTiO₃) ceramics doped donor were fabricated by the addition of polyethylene glycol (PEG) into the n-BaTiO₃ powder. The effects of PEG on the microstructure and PTCR characteristics of the porous n-BaTiO₃ ceramics have been investigated. An endotherm was found at 60 °C, with strong exotherm at 262 °C, weight loss commenced at 165 °C and was virtually complete by 265 °C from the differential thermal analysis (DTA) and thermogravimetric analysis (TGA) of the PEG. It was also found that the porosity increased and the grain size decreased with increasing PEG. The crystalline structure of n-BaTiO₃ ceramics was independent on the PEG content and the n-BaTiO₃ ceramics containing PEG showed the presence of (Ba, Sr)TiO₃ peaks only from the XRD results. The n-BaTiO₃ ceramics containing PEG showed higher PTCR characteristics than that of the n-BaTiO₃ ceramics without PEG.     

Templated Grain Growth of <001> Textured PMN-28PT Using SrTiO3 Templates

Highly textured PMN-28PT (0.72Pb(Mg_1/3Nb_2/3)O₃–0.28PbTiO₃) ceramics were produced by templated grain growth on <001> oriented platelet-shaped SrTiO₃ template particles with an aspect ratio of 10–15. The templates were aligned in PMN-28PT matrix powder via tape casting and fired in an O₂–PbO atmosphere at 1150°C for up to 15 h. This resulted in textured ceramics with a 40 micrometer grain size and without residual templates. The volume fraction of textured material (  f  ) and the orientation parameter ( r ) were quantified by fitting X-ray diffraction rocking curve data to the March–Dollase equation. Processing conditions were optimized to achieve the best possible values of f and r for the chosen templates and matrix powder. A texture fraction of at least 81 vol% and an orientation parameter of 0.2 were achieved when all random matrix grains were consumed (a perfect textured ceramic would show a texture fraction of 100 vol% and an orientation parameter of 0).     

Fabrication of Textured Bi3NbTiO9 Ceramics

Highly textured Bi₃NbTiO₉ ceramics are fabricated by normal sintering from molten salt-synthesized plate-like crystallites. Fine Bi₃NbTiO₉ plate-like crystallites (∼1 μm) not only facilitate the densification, but also enhance texture in Bi₃NbTiO₉ ceramics. Weak-agglomerated platelets exhibit higher sinterability and can be densified at a temperature as low as 1000°C, which is about 100°C lower than that of equiaxed powders prepared by directly calcining Bi₃NbTiO₉ precursor. Meanwhile, the orientation degree of textured Bi₃NbTiO₉ ceramics increases with sintering temperature. Highly oriented Bi₃NbTiO₉ (orientation degree of ∼0.91) ceramic with a relative density of ∼92% is obtained at 1150°C. Because of the oriented grain microstructure, textured Bi₃NbTiO₉ ceramic exhibits anisotropic electrical properties.     

Templated Grain Growth of Textured Bismuth Titanate

Textured bismuth titanate, Bi₄Ti₃O₁₂ (BiT), was produced by templated grain growth (TGG). Molten-salt-synthesized BiT platelets were dispersed in a matrix of 200 nm BiT powder and aligned by tape casting. Highly textured BiT was obtained with the use of only 5 vol% template particles by sintering at 1000°C for 1 h. The uniformity of the through-thickness texture is much higher than reported in the literature for BiT tapes cast with 100% platelets. Initial platelet alignment is shown to increase because of frequent interaction with the fine powder particles during tape casting. By avoiding pressure densification techniques and using only a small portion of anisometric particles, TGG is a low-cost option for fabricating textured ceramics.