(K0.5Na0.5)(TaxNb1-x)O3无铅压电陶瓷的性能特征

采用传统电子陶瓷制备工艺制备了(K0.5Na0.5)(TaxNb1-x)O3无铅压电陶瓷。研究了不同Ta含量下(K0.5Na0.5)(TaxNb1-x)O3陶瓷的晶相组成及性能特征。结果表明,(K0.5Na0.5)(TaxNb1-x)O3陶瓷在低Ta含量时形成单一斜方相固溶体,但Ta含量达到0.08mol后则有K6Ta10.8O30次晶相产生。随着Ta的加入,陶瓷的体积密度逐渐增大,居里温度(Tc)逐渐降低。当Ta含量为0.08mol时陶瓷具有良好的铁电、压电性能和介电稳定性能,其压电常数d33为76pC/N。     

氧化铋掺杂对铌酸钾钠无铅压电陶瓷性能的影响

用传统固相反应法制备了结构致密的铌酸铋钾钠[(Na0.5K0.5)1-3xBixNbO3,0≤x≤0.05]无铅压电陶瓷,研究了掺杂氧化铋(Bi2O3)对铌酸钾钠(Na0.5K0.5)NbO3(NKN)晶体结构和压电性能的影响.结果表明:当Bi2O3含量x＜0.02时,能得到具有纯钙钛矿结构的(Na05K0.5)1.3xBixNbO3陶瓷.最佳烧结温度随Bi2O3含量的增加而升高,与纯铌酸钾钠陶瓷相比,样品密度显著提高.Bi2O3掺杂量对铌酸钾钠的压电性能有很大影响,其压电常数(d33),机电耦合系数(kp,kt)随Bi2O3含量的增加先升高而后降低,并在x=0.01时达到最大值,机械品质因数(Qm)有明显提高.实验表明:当x=0.01时,(Na0.5K0.5)1-3BixNbO3无铅压电陶瓷的密度达4.42g/cm3,表现出优异的压电性能:d33=154×10-6C/N,kp=45%,kt=46%,介电损耗tanδ=3.5%,相对介电常数ε=598,Qm=138.     

含有压电陶瓷颗粒的结构陶瓷基复合材料的制备与性能

为了研究压电陶瓷颗粒对结构陶瓷力学性能的影响,把不同的压电陶瓷 颗粒加入到Al2O3结构陶瓷,发现LiTaO3与Al2O3在烧结时能稳定共存,烧结温度高于1400℃时,LiTaO3发生化,冷却后呈网状分布在AlO3基体晶界;低于1400℃烧结,LiTaO3颗粒弥散分布在Al2O3基体中,采用200MPa冷等静压成型,1300℃（保温3小时）空气气氛下无压烧结,最后于1300℃,150MPa（保温保压1h)氩气气氛下热等静压制备了LiTaO3/Al2O3陶瓷复合材料,对其显微结构与力学性能进行了研究,结果表明,LiTaO3体积分数为5％的陶瓷复合材料具有最高的抗弯强度与断裂韧性值,分别达到438．7MPa和5．4MPa.m^1/2,电畴运动和／或压电 应引起的能量耗散是一种新的陶瓷强韧化机制。     

无铅压电陶瓷的电学和力学性能(英文)

利用常规烧结方法制备出了多种A位离子掺杂的钛酸铋纳[(Bi1/2Na1/2)TiO3,BNT]无铅压电陶瓷。对BNT基陶瓷的电学性能和力学性能进行了研究。在(1-x)(Bi1/2Na1/2)0.900Ba0.088Sr0.012TiO3-x(Bi1/2K1/2)TiO3(x=0-0.14)陶瓷体系中,当x=0.10时,可获得最大压电常数(168 pC/N)。在1 kHz,这种陶瓷的介电常数、介电损耗和平面机电耦合系数分别为1 221,0.036 1和0.228 1。Curie温度随x的增加先增加,当x=0.12时,达到最高值(300℃),随后,当x值进一步增加,Curie温度降低。该种无铅压电陶瓷的Vickers硬度和断裂韧性分别为5.0 GPa和2.0 MPa.m1/2,均高于Pb(Zr,Ti)O3陶瓷。     

锑掺杂PZSN压电陶瓷烧结工艺的研究

为制备大功率低损耗压电陶瓷材料，对改性锆钛酸铅压电陶瓷Pb0.9Ba0.05Sr0.05（Zn1／3Nb2／3）0.06（Sn1/3Nb2/3）0.05Ti0.44Zr0.44O3＋0．5％Mn（NO3）2（质量分数，下同）＋x％Sb2O3的烧结工艺进行比较研究，结果表明体系优化结工艺为以300℃／h的升温速率，在1250℃处保温3h，此时对0．1％～0．4％（质量分数）的Sb2O3掺杂，均可制备出综合性能优良的压电陶瓷。当掺杂量为0．1％（质量分数）时，其tanδ，Qm，Kp，d33和ε4分别为0．47％，2251，0.538，336pC／N和1897，可满足大功率应用的要求。     

BNKT-NKS压电陶瓷的制备及电学性能研究

以碳酸盐和氧化物为原料,无水乙醇为研磨介质,采用固相法合成压电陶瓷体系0.995Bi0.5(Na0.8K0.2)0.5Ti O3-0.005(Na1-xKx)Sb O3(BNKT-NKS),并对其微结构、表面形貌、电学性能进行了分析测试。结果表明,压电陶瓷样品都能形成单一钙钛矿固溶体结构,具有较好的电学性质:x=30%时,d33=149 p C/N,kp=0.315,Qm=139,tanδ=0.037;x=10%时,tanδ=0.037。     

BNKT-NKS压电陶瓷的制备及电学性能研究

以碳酸盐和氧化物为原料,无水乙醇为研磨介质,采用固相法合成压电陶瓷体系0.995Bi0.5(Na0.8K0.2)0.5Ti O3-0.005(Na1-xKx)Sb O3(BNKT-NKS),并对其微结构、表面形貌、电学性能进行了分析测试。结果表明,压电陶瓷样品都能形成单一钙钛矿固溶体结构,具有较好的电学性质:x=30%时,d33=149 p C/N,kp=0.315,Qm=139,tanδ=0.037;x=10%时,tanδ=0.037。     

不同压电陶瓷体积分数对1-3-2型压电复合材料性能的影响

以环氧树脂为基体,铌镁锆钛酸铅[0.375Pb(Mg1/3Nb2/3)O3·0.375PbTiO3·0.25PbZrO3,PMN]为压电功能体,采用切割-浇注法制备了1-3-2型压电复合材料.分析讨论压电陶瓷体积分数(φ,下同)对1-3-2型压电复合材料压电性能、介电性能及声阻抗的影响.结果表明:随着PMN的φ的增加,复合材料的压电应变常数(d33)和声阻抗(2)增大;相对介电常数(εr)几乎呈线性增加,且当PMN的φ为47.47%时,复合材料的εr=1 660,远小于纯PMN陶瓷的(εr=4000).压电电压常数(g33)及介电损耗(tan δ)则呈下降趋势;与PMN相比较,1-3-2型压电复合材料厚度方向的谐振明显增强,机械品质因数(Qm)显著降低;随着PMN的φ的增加,复合材料的平面机电耦合系数(Kp)减小,而厚度机电耦合系数(Kt)增加.     

超声压电马达用陶瓷材料的研究

研究了钡锶锑锰等离子掺杂对锆钛酸铅(PZT)系压电陶瓷的介电、压电性能和体积密度的影响。实验结果表明:对于Pb0.95Ba0.03Sr0.02(Zr1-yTiy)O3+xwt%MnSb2O6(PBSZTMS),在x=1.5、Zr/Ti=52/48附近获得了优越的压电活性。对于Pb0.95Ba0.03Sr0.02(MnSb2O6)x/3(Zr54Ti46)1-xO3(PBSMSZT),综合性能较好的组成点出现在x=0.05处。对于PbaBabSrc(MnSb2O6)x/3(Zr1-yTiy)1-xO3+zwt%MnSb2O6系列配方,发现Sr2+和Ba2+的共同添加会使样品致密度降低,介电常数、介质损耗和压电常数增加;当a=1,b=0,c=0,x=0.03,y=0.48,z=0.76时,获得了综合性能较好的陶瓷材料,有望应用于大功率超声压电马达器件领域。     

Ba(Zr_(0.055)Ti_(0.945))O_3含量对[(Na_(0.80)K_(0.16)Li_(0.04))_(0.5)Bi_(0.5)]TiO_3陶瓷性能的影响

系统研究(1-y)[(Na0.80K0.16Li0.04)0.5Bi0.5]TiO3-yBa(Zr0.055Ti0.945)O3无铅压电陶瓷,获得压电应变常数高达185pC/N的0.94[(Na0.80K0.16Li0.04)0.5Bi0.5]-TiO3-0.06Ba(Zr0.055Ti0.945)O3压电陶瓷。样品的晶体结构为三方相、四方相共存,处于准同型相界(morphotropic phase boundary,MPB)附近。该类陶瓷室温MPB的摩尔(下同)含量为0.050y0.065。样品y=0.060在40°左右的(003)、(021)双峰与46.5°左右的(002)、(200)双峰分裂最明显。随着Ba(Zr0.055Ti0.945)O3含量的增加,铁电相-反铁电相相变温度(θd)升高、反铁电相-顺电相相变温度(θm)降低;θd和θm的温差越来越小,材料的弛豫性逐渐降低。     

射流撞击过程中的高频压力脉动特性

引　言利用两束射流相互撞击或单射流撞击靶在微细颗粒制备、多相流快速微观混合及团聚颗粒单分散过程中具有特殊优点。用作预混合器或反应器 ,能够强化微细颗粒的成核与生长环境在微观尺度上的均匀性 ,尤其对于快速反应体系 ,可实现液液或液固多相流快速微观混合 ,有效控制反应过程和产物指标 .Ｍａｈａｊａｎ等[1] 利用两束撞击流实现流体的快速微观混合以合成超细微粉 ,并用萘酚与重氮苯磺酸两步反应表征两束撞击流体数十毫秒的微观混合时间 ,关联微观混合时间与射流速度的关系 ,通过控制射流的微观混合时间控制合成超细微粉的粒度分布 .…     

Current Oscillation of Piezoelectric–Ceramic Vibrators Driven by a Constant High Electric Field

Current oscillation will occur when a piezoelectric ceramic vibrator is driven by a high electric field. The mechanism of current oscillation is discussed, based on the results of the present experiment. Ring-shaped lead zirconate titanate (PZT) piezoelectric vibrators are driven by a 5.65 V electric field with a fixed frequency of slightly less than resonance, to form an oscillating current. The sample current, temperature, and phase between the driven electric field and sample current are recorded. The resonance frequency of PZT rings shifts in the direction of low frequency under a high electric field due to the heat produced by dissipated power, and then shifts back due to the effects of aging, which results in current oscillation. The oscillation phenomenon is explained according to the production of strong internal stresses due to abrupt change in temperature, and then, aging process through the rearrangement of domains to relieve various stresses.     

含N,N-二硝基哌嗪无烟改性双基推进剂的燃烧性能

以CMDB推进剂为基础,用N,N-二硝基哌嗪(DNP)替代推进剂中的RDX,研究了DNP含量、燃烧稳定剂(CaCO3、TiO2、MgO及Al2O3)、燃烧催化剂(铅盐、铅盐/铜盐、铅盐/铜盐/炭黑)对DNP-CMDB推进剂燃烧性能的影响。结果表明,DNP可明显降低无烟CMDB推进剂的燃速,当DNP完全替代RDX时,在18MPa压强下推进剂的燃速降低约68%;铅盐/铜盐/炭黑燃烧催化剂复配体系能够有效降低DNP-CMDB推进剂的燃速压强指数,使其出现平台燃烧效应。     

新型弛豫铁电单晶及其超声医学应用

新型弛豫铁电单晶是一类钙钛矿结构的固溶体材料,具有比传统压电陶瓷Pb(Zr,Ti)O_3更为优越的压电性能,在医用超声成像、声纳、微位移器等方面具有广阔的应用前景。综述了Pb(Zn_(1/3)Nb_(2/3))O_3-PbTiO_3(PZNT),Pb(Mg_(1/3)Nb_(2/3))O_3-PbTiO_3(PMNT)等新型弛豫铁电单晶在生长、性能等方面的研究进展,介绍了弛豫铁电单晶在医用超声换能器方面的应用。     

Preparation of tritium breeding Li2TiO3 ceramic pebbles via newly developed piezoelectric micro-droplet jetting

Wet methods as an emerging technique for the preparation of millimeter-sized tritium breeding ceramic pebbles, but the imposed air pressure as the driving forces to extrude slurry droplets are fluctuating during the reciprocating extrusion process, which caused a slight inconsistency in pebble sizes. In this study, a piezoelectric micro-droplet jetting approach was proposed by introducing a piezo-driven valve and modifying the slurry barrel mechanism to realize the air pressure invariable. A self-developed piezoelectric micro-droplet jetting device was successfully utilized to prepare Li₂TiO₃ green pebbles with coefficients of variation being lower than 2.7%. The size of the green pebbles could be precisely controlled in the range of 0.88–1.37 mm by manipulating the nozzle diameter, the air pressure, and the jetting time. The pebbles sintered at 1000°C for 3 h possessed a small grain size of ∼5.9 μm, a satisfied relative density of ∼84.8% T.D., and a high crush load of ∼25.7 N, implying the prepared pebbles could be used as a promising solid tritium breeding material in fusion reactors. These findings are anticipated to provide new opportunities for the highly efficient preparation of size-controllable tritium breeding ceramic pebbles.     

Fabrication and characterization of a tiny PZT thick-film longitudinal-bending coupled drive vibrator using electrohydrodynamic jet printing

This paper describes a fabrication method of a novel type of micro piezoelectric thick-film longitudinal-bending coupled (LBC) vibrator with a length of 8 mm and thickness of 0.34 mm using electrohydrodynamic jet (E-jet) printing. The LBC micro-vibrator was designed, and a frequency sensitivity analysis of the structural parameters was implemented. When the thickness of the lead zirconate titanate (PZT) thick-film element of the vibrator reached 76 μm, tuning of the composite-mode frequency consistency could be achieved. The micro-vibrator was then fabricated by depositing the PZT thick film directly on the surface of the elastic body using E-jet printing, and the film thickness was flexibly adjusted by tuning the number of prints, thus avoiding the problems of insufficient PZT thin film thickness (≤1 μm) and excessive bulk PZT ceramic volume. Micro-morphological observations showed that the printed thick film was dense and smooth, with a thickness of approximately 76 μm. Furthermore, the vibration mode frequency of the vibrator differed from the test resonant frequencies by only 0.92%, and the vibrator could achieve driving motion with a volume and an excitation voltage approximately one-tenth of that of a bulk piezoelectric motor. Moreover, the unit power density was 0.36 W kg⁻¹ V⁻¹, which is 1.6 times higher than that of a large bulk piezoelectric motor, indicating that the vibrator has good potential for small-space and low-voltage applications.     

Improved strain and transduction values of low-temperature sintered CuO-doped PZT-PZNN soft piezoelectric materials for energy harvester applications

In this study the low-temperature sintering effects and improved piezoelectric properties of CuO-doped 0.69 Pb(Zr0.47Ti0.53)O3-0.31[Pb(Zn0.4Ni0.6)1/3Nb2/3]O3 ceramics were investigated. At high temperatures, a sintered Pb(Zr,Ti)O3–Pb(Zn,Ni)NbO3 material has excellent piezoelectric properties such as a high piezoelectric charge coefficient (d33), high electromechanical coupling coefficient (kp), and high relative dielectric permittivity (εr). However, low-temperature sintering of functional ceramics is important for industrial device applications. For sensor applications, sintering or fabrication temperature is important because processing temperatures can interfere with process and material compatibility. Therefore, in this study, low-temperature sintering effects were investigated by employing low-temperature sintering aids while maintaining the piezoelectric properties. CuO was selected as the sintering aid for these applications. We will investigate and discuss the effects of the low-temperature sintering aid of CuO on the Pb(Zr,Ti)O3–P(Zn,Ni)NbO3 material in device applications. By employing the CuO dopant to Pb(Zr,Ti)O3–P(Zn,Ni)NbO3 material, the strain and transduction values were increased while reducing the sintering temperature.     

Preparation of low residual silicon content Si-SiC ceramics by binder jetting additive manufacturing and liquid silicon infiltration

Complex silicon carbide (SiC) ceramic components are difficult to fabricate due to their strong covalent bonds. Binder jetting (BJ) additive manufacturing has the outstanding advantages of high forming efficiency and no thermal deformation, especially suitable for printing complex structure SiC components. This study tried to obtain low silicon content silicon carbide ceramics by binder jetting followed by phenolic resin impregnation and pyrolysis (PRIP) and liquid silicon infiltration (LSI). BJ was used for the SiC green parts fabrication, and the highest compressive strength (7.7 ± 0.3 MPa) and lowest dimensional deviations (1.2–1.6 mm) were obtained with the printing layer thickness of 0.15 mm. Subsequently, PRIP treatments were introduced to increase the carbon content for the following LSI process. As the number of PRIP cycles increased, the carbon density of SiC/C preform increased and the porosity decreased. After the LSI treatment, the final Si-SiC composites processed with 2 PIRP cycles reached the highest flexural strength (257 ± 14.26 MPa) and the best wear resistance. This was attributed to the low residual silicon content (10.2 vol%) and almost no residual carbon. Furthermore, several complex structural components were fabricated using these methods. The preparation of complex components verifies the feasibility of BJ and LSI for manufacturing high-strength and high-precision SiC ceramics. Besides, this work hopes to provide technical guidance for the preparation of complex SiC composites in the future.     

大型射流流化床的流型转变与射流深度

在高 8m、直径 0 .5m的大型射流流化床中 ,通过摄像分析法 ,研究了射流、喷流两种流型的转变 .结果表明在低静床高、大射流气速下易出现喷流 ;喷流出现时 ,功率谱主频射流气速曲线上出现一转折点 .转折点射流气速与摄像法得出的流型转变射流气速相同 .提出了射流、喷流流型转变关系式 .同时发现射流深度随射流气速变大而增大 ,结合二维射流床射流深度的研究结果 ,得出了射流深度的预测式