影响流延成形陶瓷基板的质量因素

流延成形是生产陶瓷基板的主要成形方法。笔者在长期的流延生产实践中,总结出影响陶瓷基板成形的质量因素:流延浆料质量、流延机的控制精度及其流延工艺。     

氧化铝陶瓷基片的非水基流延成型工艺与性能研究

采用非水基流延法制备了氧化铝陶瓷基片,讨论了非水基流延工艺参数对基片性能的影响。实验结果表明:以甲苯和正丁醇混合液为溶剂,PVB为粘结剂,PEG-400为增塑剂,鱼油为分散剂,当混合溶剂的最佳配比为甲苯:正丁醇为5:3、增塑剂与粘结剂的比值为0.4、粘结剂加入量为5wt%、分散剂加入量为0.6wt%时可获得粘度为2100～3500mPa·s的适合流延的浆料,将流延制得的氧化铝基片生坯在1575℃烧成,密度为3.78g/cm3,介电性能优良。     

堇青石陶瓷基片水基流延成型工艺与性能研究

利用水基流延法,选用聚丙烯酸(PAA)为分散剂,聚乙烯醇(PVA)为粘结剂,聚乙二醇(PEG)为增塑剂,正丁醇为除泡剂,成功制备出了表面光滑、结构均匀、柔韧性良好的堇青石流延生带.当发现分散剂PAA含量为0.9%(wt)、粘结剂用量为7%～10%(wt),增塑剂的加入量为粘结剂用量的60%～90%,pH值为10左右时可以制备出稳定性良好、流动性适宜的堇青石流延浆料.然后对流延生带进行差热分析(DTA)和热重分析(TGA),在此基础上确定了流延生带的排胶温度为600℃,以及堇青石流延生带的烧结温度为1440℃,并在该温度保温70分钟的烧结条件下,获得了强度和致密度都较高的流延基片,其中烧结较好的流延基片的相对密度达96.14%.     

水基流延工艺制备陶瓷材料的研究

流延法作为制备片层材料的重要工艺已经被陶瓷研究者广泛应用.但是,有机流延体系带来的环境污染、毒性及易燃性等问题已被社会所关注.因此,研究无毒、无污染的水基流延工艺已得到材料界的广泛重视.本文主要概述了国内外水基流延工艺的研究现状,重点介绍了PVA体系、丙烯酰胺凝胶流延体系、纤维素类粘结剂体系及乳胶体系的不同特点;从粘结剂、分散剂、增塑剂等多个角度分析了影响水基流延工艺的技术因素,并提出了很好的解决方法,最后介绍了乳胶体系水基流延工艺在制备片状或层状陶瓷材料方面的应用.     

钙长石陶瓷基片的水基流延成型工艺研究

采用水基流延成型钙长石陶瓷基片坯体,研究分散剂、pH值、粘结剂及塑化剂对浆料流动性能的影响.实验结果表明:当浆料中固相含量为48vol%时,以聚丙烯酸胺为分散剂,浆料的pH值10,粘结剂含量为6.0wt%～8wt%时,增塑剂含量为4wt%～6wt%时,可以制备出稳定性良好、流动性适宜的钙长石流延浆料.通过SEM可以看出,高分子膜均匀包覆在钙长石颗粒表面,并且钙长石颗粒分布均匀,没有明显较大的孔隙.     

流延法制备陶瓷薄片的研究进展

流延成型是一种目前使用较广泛,能够获得高质量、超薄型陶瓷薄片的成型方法.本文论述了流延成型时有机物(包括溶剂、分散剂、粘结剂、增塑剂等)的选择原则、浆料的制备以及流延工艺过程,并对影响流延膜厚度和流延膜质量的因素进行了分析讨论,同时提出了改进流延膜质量的措施.     

陶瓷材料流延成型工艺的研究进展

流延成型是制备电子器件用陶瓷基板的关键技术,本文系统地论述了流延浆料的组成,如陶瓷粉末、溶剂、分散剂、粘结剂、增塑剂以及其他添加剂,并且介绍了这些组分的功能以及选择的原则;概述了致密陶瓷材料与多孔陶瓷材料的几种新型流延成型工艺的研究现状,如流延-温压成型工艺、凝胶流延成型工艺、等静压流延成型工艺、流延-冷冻法与相转化流延法等;根据流延技术的最新研究成果,对流延成型技术进行展望,并提出了一些见解     

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。     

掺杂CeO2对流延成型制备的氮化铝陶瓷性能的影响

以氮化铝(AlN)粉末为原料,掺杂10%～15%的CeO_2,采用流延成型工艺制备AlN陶瓷生坯;排胶后在氮气气氛下1 775℃保温4h,采用常压烧结制备静电卡盘用AlN陶瓷(体积电阻率为10~(11)～10~9Ω·cm)。研究了排胶升温速率对生坯的表面形貌以及CeO_2掺杂量对烧结体的电学与热学性能、微观组织和物相组成的影响。结果表明:在200～450℃之间升温速率为0.2℃·min~(-1)的条件下排胶后,AlN陶瓷生坯形貌完整、无裂纹和翘曲;在CeO_2掺杂量为14%时,AlN陶瓷烧结体可以获得较优的综合性能,致密度96.82%,热导率99 W·m~(-1)·K~(-1),体积电阻率4.75×10~(10)Ω·cm。显微结构分析表明,随着CeO_2掺杂量的增加,形成的铈铝酸盐晶间相逐渐由点状分布变为连续分布,有利于导电通路的形成,从而降低AlN陶瓷烧结体体积电阻率。     

Mn离子掺杂对Ba_(0.2)Sr_(0.8)Zr_(0.18)Ti_(0.82)O_3陶瓷烧结和电学性能的影响

采用溶胶凝胶法制备x Mn-Ba0.2Sr0.8Zr0.18Ti0.82O3(BSZT)(x=0mol%、1mol%、2mol%、3mol%)的陶瓷粉末,以传统工艺制备Mn离子掺杂的BSZT陶瓷。研究Mn离子掺杂浓度对BSZT陶瓷烧结特性、物相结构、介电性能、击穿场强以及储能密度的影响。结果表明,Mn离子掺杂降低了BSZT陶瓷的烧结温度,同时降低其介电常数以及介电损耗,提高了击穿场强和储能密度。在1400℃下烧结的2mol%Mn离子掺杂BSZT陶瓷较未掺杂BSZT陶瓷的烧结温度降低了100℃,相对密度为96.3%;1 k Hz处介电常数约为497、介电损耗为3.6%;最大击穿场强为12.595 k V/mm;最大储能密度为0.374 J/cm3。     

Effect of La substitution on energy storage properties of (Bi0.2Na0.2Ca0.2Ba0.2Sr0.2)TiO3 lead-free high-entropy ceramics

In this study, a novel lead-free high-entropy ceramic (HEC) system, (Bi_0.2Na_0.2Ca_0.2Ba_0.2Sr_0.2)_(1–3x/2)La_xTiO₃ (0 ≤ x ≤ 0.15) (abbreviated as BNCBST-xLa), was designed to enhance energy storage performance through La substitution and prepared via a hydrothermal method. Results indicate that La doping at A site in BNCBST induces lattice distortion and further improves dielectric relaxation. Moreover, grain growth is inhibited by the La content, which results in an increase in the insulation resistance and thus significant enhancement in the electric breakdown strength (E_b). Accordingly, the system with x = 0.03 exhibits an excellent recoverable energy density (W_rec) of 2.43 J/cm³ and a high energy storage efficiency (η) of 85.5% under a great E_b of 245 kV/cm, together with wide temperature stability (W_rec and η vary within ± 8.3% and ± 1.1% at 30–150°C). The findings of this study suggest that the obtained La-modified BNBCST HECs are promising for energy storage applications.     

Crystal structure,relaxor behaviors and energy storage performance of (Sr0.7Ba0.3)5LaNb7Ti3O30 tungsten bronze ceramics

In this work, a new (Sr_0.7Ba_0.3)₅LaNb₇Ti₃O₃₀ system ceramic with a filled tetragonal tungsten bronze structure was proposed and fabricated by the traditional solid phase method. Crystal structure, relaxor behaviors and energy storage capabilities were studied. Large relaxor activation energy indicates a “weakly coupled relaxor” mechanism, which is advantageous for obtaining better energy storage performance, and lower conductance activation energy can further prove the formation of the filled tungsten bronze structure. More importantly, a dielectric breakdown strength of up to 35.5 kV/mm was obtained. The releasable energy density and efficiency at 24 kV/mm are 1.36J/cm³ and 91.9%, respectively. In addition, due to the high current density and high dielectric breakdown strength, a current density of 477.5 A/cm² and a power density of 42.9 MW/cm³ are achieved, meaning that SBLNT ceramic is a potential candidate dielectric ceramic for energy storage.     

施主掺杂多晶（Sr,Ba）TiO3微观结构和介电性能的研究

系统地研究了施主掺杂对多晶ＳｒＴｉＯ３（Ｓｒ，Ｂａ）ＴｉＯ３微观结构和介电性能的影响。ＳＥＭ观察表明：掺杂不同施主，对多晶ＳｒＴｉＯ３晶粒生长起着不同的作用。施主掺杂量影响多晶ＳｒＴｉＯ３，（Ｓｒ，Ｂａ）ＴｉＯ３晶粒的半导化程度及试样介电特性。     

激励方式对锆钛酸铅钡锶压电陶瓷介电性能的影响

采用扎膜工艺和固相反应法制备了(Pb0.70Ba0.26Sr0.04)(Zr0.52Ti0.48)O3(PBSZT)压电陶瓷。通过扫描电子显微镜和X射线衍射表征PBSZT陶瓷的结构和物相组成,用电容介损测试仪表征压电陶瓷的介电性能与激励场强,通过自建电路集成直流电源、标准电容,在低频频率特性测试仪上得到偏场强度对压电陶瓷介电性能的影响关系。结果表明:压电陶瓷材料的介电性能随着加载的电场强度的增大先逐渐升高,而后出现拐点开始降低;在偏压电场中,自由电容CT随正向偏场强度的增加逐渐减小,但随着反向偏场强度的增加逐渐增大。tanδ则随着正、反偏场强度的增加均呈现上升;压电陶瓷的机电耦合系数kp与偏场强度的关系是以0点为界,随着负偏场增强,kp略显下降,反之,随正偏场增强,kp缓慢增大。因此,压电陶瓷应用时应避开强场损耗高点;并在环境中施加正向偏场,有助于抑制压电陶瓷性能衰减。     

The Influence of La Doping and Heterogeneity on the Thermoelectric Properties of Sr3Ti2O7 Ceramics

La‐doping mechanisms and thermoelectric properties of Sr₃Ti₂O₇ Ruddlesden–Popper (RP) ceramics sintered under air and flowing 5% H₂ at 1773 K for 6 h have been investigated. Changes in lattice parameters and conductivity revealed a limited interstitial anion mechanism (~1 at.%) based on La³⁺ + ½O^2?→Sr²⁺, which resulted in insulating samples when processed in air. In contrast, electronic donor‐doping (La³⁺ + e^? → Sr²⁺) and oxygen loss [O^2? → ½ O₂ (g) + 2 e^?] are the dominant mechanism(s) in 5% H₂‐sintered ceramics with a solution limit of ~5 at.%. The increased solubility limit is attributed to the formation of Ti³⁺ during reduction, which compensates for the extra positive charge associated with La on the A‐site and also to the occurrence of oxygen loss due to the reducing conditions. For 5% H₂‐sintered samples, an insulating surface layer was formed associated with SrO volatilization and oxygen uptake (during cooling) from the sintering. Unless removed, the insulating layer masked the conductive nature of the ceramics. In the bulk, significantly higher power factors were obtained for ceramics that were phase mixtures containing highly conductive perovskite‐based (Sr,La)TiO_3?δ (ST). This highlights the superior power factor properties of reduced perovskite‐type ST phases compared to reduced RP‐type Sr₃Ti₂O₇ and serves as a precaution for the need to identify low levels of highly conducting perovskite phases when exploring rare‐earth doping mechanisms in RP‐type phases.     

Study of the structure,electrical properties,and energy storage performance of ZnO-modified Ba0.65Sr0.245Bi0.07TiO3 Pb-free ceramics

Barium titanate ceramic is frequently used as a ferroelectric material and can be applied in the pulse power field in energy storage devices. Its properties, including dielectric, ferroelectric, and energy storage properties, can be significantly improved through doping. In this work, we prepared a series of (1-x)Ba_0.65Sr_0.245Bi_0.07TiO₃-xZnO (x = 0.005, 0.01, 0.02, 0.03) lead-free bulk relaxor ferroelectric ceramics by a traditional die-pressing processing route. The uniformity of the grain sizes for these ceramics was improved, and the grains were refined when a certain amount of ZnO was introduced into BaTiO₃-based ceramics. In addition, the breakdown strength was improved in the case where the relaxor behavior was not significantly improved. It should be noted that the sample doped with 0.02 mol Zn showed the maximum room-temperature storage density (1.51 J/cm³) at the largest electric field strength (210 kV/cm). At the same time, this ceramic exhibited good stability to temperature (60–150 °C) and frequency (10–100 Hz) variations, as well as fantastic fatigue resistance (10,000 charge-discharge cycles). This paper presents in-depth studies of the structure, morphology, electrical properties, and energy storage performance of ZnO-modified BaTiO₃-based ceramics.     

CuO-B2O3掺杂对Ba4Sm9.33Ti18O54陶瓷烧结性能及微波介电性能的影响

研究了CuO-B2O3助剂对Ba4Sm9.33Ti18O54陶瓷的烧结性能和介电性能的影响,结果表明:通过共添加CuO-B2O3助剂(CB),陶瓷的烧结温度可以从1350℃降低到1050℃左右,当CB添加量达到10％时,产生第二相Ba2Cu(BO3)2,研究了CB的添加,对介电性能的影响,当CB的添加量为1wt％时,有以下微波介电性能ε=62.7,Q·f=4 270 GHz,τf=-11.1 ppm/℃.     

Effects of annealing temperatures on energy storage performance of sol-gel derived (Ba0.95, Sr0.05) (Zr0.2, Ti0.8) O3 thin films

Dielectric polarization and breakdown strength of dielectrics generally show directly and inversely dependent upon their crystallization, respectively. Therefore, achieving the maximum energy storage density should be expected by controlling the crystallization. A serial of ferroelectric (Ba_0.95, Sr_0.05)(Zr_0.2, Ti_0.8)O₃ (BSZT) thin films were prepared by the sol-gel method. Effects of annealing temperatures on the microstructure, dielectric and energy storage performance of the films were investigated. The results indicate that BSZT thin films annealed at 600 °C for 30 min demonstrate the highest recoverable energy density and efficiency (50.5 J/cm³ and 91.9%). Such superior energy storage performance is attributed to an ultrahigh electric breakdown strength (6.65 MV/cm) induced by the dense amorphous-nanocrystalline microstructure. This work creates a new way for optimizing the energy storage performance of dielectric thin films via balancing their dielectric polarization and breakdown strength at appropriate heating processing temperature.     

Critical role of CuO doping on energy storage performance and electromechanical properties of Ba0.8Sr0.1Ca0.1Ti0.9Zr0.1O3 ceramics

CuO doped Ba_0.8Sr_0.1Ca_0.1Ti_0.95Zr_0.05O₃ (BSCTZ) ceramics were prepared by a modified mechano-chemical activation technique with the aim of improving energy storage properties for ceramic capacitor applications. CuO can effectively improve the microstructural characteristics along with a transformation of BSCTZ from classical ferroelectric to relaxor, which is the prime requirement for obtaining high discharge energy density and energy efficiency. The effect of CuO doping on the microstructural, ferroelectric, dielectric, and piezoelectric properties have been systematically studied. The study reveals that an appropriate amount of CuO doping can significantly enhance the morphological properties along with improvement in material density, which is very beneficial in a material for attaining improved energy storage performance. The BSCTZ sample with 3 mol% CuO doping has shown a highly dense microstructure, high saturation polarization (33.01 μC/cm²), low remnant polarization (6.74 μC/cm²), ultrahigh discharge energy density (1.81 J/cm³) and high energy efficiency (81.9%). The CuO doping in BSCTZ has also led to a slight improvement in breakdown strength and electromechanical properties compared to pure BSCTZ ceramics, which is mainly attributed to excellent density and optimum grain size of the material.