La置换Pb对Sb掺杂PZT压电陶瓷介电和压电性能的影响

研究了Pb1–xLax(Zr1–yTiy)1–x/4O3+1.5%(质量分数)Sb2O5陶瓷(PLSZT)的介电、压电性能及其微观结构,获得了高压电性能、小晶粒尺寸的压电陶瓷材料。结果显示:x≤5%时,晶体结构为纯钙钛矿相;x>5%时,为钙钛矿和焦绿石两相混和物。随着x的增大,介电常数和压电常数均呈现先增大后减小的趋势。介电常数在x=6%、y=0.45时最大,最大介电常数εmax≈3900,介电损耗tgδ≈1.8%;压电性能在x=4%、y=0.45时最强,压电应变常数d33≈600pC/N,径向机电耦合系数kp≈0.7,厚度机电耦合系数kt≈0.51,此时的平均晶粒尺寸约为2μm。     

锑锰掺杂对Pb_(0.80)Ca_(0.20)TiO_3陶瓷显微结构及性能的影响

以Ca CO3、Sb2O3、Pb3O4、Ti O2、Mn CO3为原料,采用传统固相法制备Pb0.80Ca0.20Ti O3陶瓷,研究了掺入2%~10%(摩尔分数)的Sb2/3Mn1/3对Pb0.80Ca0.20Ti O3陶瓷显微结构、电阻率、介电性能、热释电性能的影响。结果表明:当Sb2/3Mn1/3掺杂量≤5%时为单一钙钛矿相,晶粒随掺杂量的增大而减小,致密性逐渐变好。当Sb2/3Mn1/3掺杂量5%时,陶瓷为钙钛矿和焦绿石两相混合物,致密性和晶粒均匀性变差。加入Sb2/3Mn1/3后,陶瓷电阻率数量级由108增加到1012,介电损耗大幅降低,热释电系数增大,探测率优值Fd显著提高。在Sb2/3Mn1/3掺杂量为5%时,获得了高电阻率、综合热释电性能良好、晶粒尺寸小的热释电陶瓷材料。     

(1-x)Ba4Sm9.33Ti18O54-xCa0.61Nd0.26TiO3系微波介质陶瓷

采用固相合成法制备了(1-x)Ba4Sm9.33Ti18O54-xCa0.61Nd0.26TiO3[(1-x)BST-xCNT]系微波介质陶瓷.探讨了组成、烧结温度对微波介质陶瓷结构、介电性能的影响.x＜0.6时,(1-x)BST-xCNT陶瓷为正交结构的新型钨青铜单相.x≥0.6时,相继出现了第二相Sm2Ti2O7和钙钛矿相,最终形成钙钛矿单相.微波介质陶瓷的介电常数ε随x的增大持续升高,品质因子Qf值则先增大后迅速减小再急剧增大.1 325～1 350 ℃烧结样品的微波介电性能达到最佳:x=0时,ε=75,Qf=8985GHz,谐振频率温度系数τf=-8.2×10-6/℃;x=0.2时,ε=75,Qf=9 552GHz,τf=-14.4×10-6/℃;x=1时,ε=108.9,Qf=14919GHz,τf=236.2×10-6/℃.     

BaCu0.5W0.5O3掺杂改性Li0.04Na0.52K0.44Nb0.86Ta0.140Sb0.04O3无铅压电陶瓷

以传统固相法制备了(1-x)Li0.04Na0.52K0.44Nb0.86Ta0.10Sb0.04O3-xBaCu0.5O3[简称(1-x)LF4-xBCW]无铅压电陶瓷,研究了不同BCW掺杂量(x=0%,0.1%,O.2%,O.5%,1%,摩尔分数)对LF4陶瓷的显微结构和电性能的影响.结果表明:引入BCW后,材料仍为钙钛矿结构,当x≥1%时,样品由四方相向正交相转变,出现To-t,Tc则随BCW掺入量的增加向低温区移动.BCW掺杂量对LF4的电性能起到"硬性"掺杂作用,其压电常数d33,平面机电耦合系数kp,介电损耗tan δ和介电常数εr均随着BCW含量的增加而降低,而机械品质因素Qm整体提高.此外,BCW的掺入降低了陶瓷的烧结温度并提高了其密度.     

Sb2O5和Bi2O3添加剂对Ag(Nb1-xTax)O3陶瓷结构、形貌和性能的影响

研究了Sb2O5和Bi2O3添加剂对Ag(Nb1-xTax)O3陶瓷材料的结构、形貌和介电性能的影响.结果表明:当Sb2O5和Bi2O3的质量分数较少(＜2.5%)时,不会影响Ag(Nb1-xTax)O3的钙钛矿结构,但能促进其烧结,使所得陶瓷样品更均匀致密.添加适量的Sb2O5和Bi2O3均可使Ag(Nb1-xTax)O3的介电常数(ε)增大,介电损耗(tgδ)减小,介电性能的温度稳定性得到改善.Bi2O3较Sb2O5对降低Ag(Nb1-xTax)O3陶瓷损耗及改善温度稳定性的效果更佳.     

固溶率因子R对(Pb,Ca,La)(Fe,Nb)O3陶瓷微波介电性能的影响

研究了 A 位La3+的电荷平衡取代[(Pb0.5Ca0.5)1-xLa2x/3](Fe0.5Nb0.5)O3 和电荷非平衡取代(非化学计量化合物)[(Pb0.5Ca0.5)1-xLax]*(Fe0.5Nb0.5)O3+δ(PCLFN)系统的微波介电性能.研究结果表明, 实际的取代式是[(Pb0.5Ca0.5)1-xLa2x/3+R(1-x)](Fe0.5Nb0.5)O3+δ, 其中R是固溶率因子, 它影响着A位La3+取代陶瓷的微波介电性能.当R＞0时, A位的电荷平衡取代[(Pb0.5Ca0.5)1-xLa2x/3](Fe0.5Nb0.5)O3将增加其介电损耗, x=0.05～0.10时, Qf＜800 GHz.A位的电荷非平衡取代[(Pb0.5Ca0.5)1-xLax](Fe0.5Nb0.5)O3+δ却能改善其微波介电性能, 这是因为过剩的La3+与(Pb,Ca)2+的固溶度能够消除氧空位.当x≤0.02时, 能够形成单相的钙钛矿相, 随着La3+取代量的增加,过剩的La3+将导致形成第二相焦绿石相,且第二相的量正比于过剩的La3+量.介电常数K随x增加而下降是由于焦绿石相随x增加的结果.当 x=0.02～0.075, [(Pb0.5Ca0.5)1-xLax](Fe0.5Nb0.5)O3+δ陶瓷有很好的微波介电性能, 介电常数K＞100, Qf值为5 525～6 105 GHz, 频率温度系数αf为7×10-6～15.7×10-6/℃, 当x=0.10时, Qf值达到极大值6 482 GHz.     

Mg4Nb2O9/CaTiO3复合介质陶瓷的结构和介电性能

以1.7%(质量分数)V2O5为烧结助剂,采用传统固相反应法制备了(1-x)Mg4Nb2O9 xCaTiO3[(1-x)MN-xCT]颗粒复合微波介质陶瓷.研究了陶瓷的微观结构和微波介电性能.结果表明:当0.5≤x≤0.7时,经1 150℃烧结5 h制备的(1-x)MN-xCT样品仍为Mg4Nb2O9和CaTiO3相,没有生成其它新相,在不同相之间存在元素扩散.当x从0.3增加到0.7,样品的相对介电常数(εr)和谐振频率(f)温度系数(τf)随x值的增加而增大,而品质因数(Q)却随x增大而降低.当x=0.5,1 150℃烧结5h后,获得的0.5Mg4Nb2O9/0.5CaTiO3 1.7%V2O5微波介质陶瓷的εr=20,Qf=48000 GHz(f=8 GHz),τf=12×10-6/℃.     

添加剂对Ba(Zn_(1/3)Nb_(2/3))O_3-Sr(Zn_(1/3)Nb_(2/3))O_3陶瓷介电性能的影响

研究了MnCO3,BaZrO3对 0 .35Ba(Zn1 /3Nb2 /3)O3(BZN) -0 .65Sr(Zn1 /3Nb2 /3)O3(SZN)陶瓷介电性能的影响。研究表明 :添加MnCO3,BaZrO3时 ,对陶瓷的烧结均起促进作用 ,增大介电常数。加入 1% (质量分数 )的MnCO3可使陶瓷具有较小的介质损耗 ,同时MnCO3对陶瓷的介电常数温度系数具有正向调整作用。加入BaZrO3后通过生成液相而减少了第二相Ba5Nb4O1 5,BaNb2 O6 的生成。所制备的 ( 0 .35BZN -0 .65SZN) 0 .1%MnCO3陶瓷的εr≈ 43.6,αε≈ -8× 10 - 6 /K ,tanδ =0 .6× 10 - 4 ,且烧结温度低于 130 0℃。     

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。     

W、Zr共同掺杂对铌酸钾钠基无铅压电陶瓷的影响

采用传统固相烧结法制备了0.94(Na0.535K0.48)Nb1–x(W0.5Zr0.5)xO3–0.06Li Sb O3(x=0,0.01,0.02,0.03,0.04)无铅压电陶瓷,其中,钨和锆以摩尔比为0.5:0.5组成掺杂共同体取代Nb,改变(W0.5Zr0.5)掺杂量x,观察钙钛矿结构B位异价元素的掺杂对铌酸钾钠基无铅压电陶瓷的影响。结果表明:陶瓷的晶体结构随着x的增加由四方相转变为正交相,晶格间距减小。掺杂量x=1%时,陶瓷的综合性能良好,压电常数为203 p C/N,机电耦合系数为0.309,相对介电常数为813,Curie温度为350℃,烧结性能也得到了提高。     

COMPARISON OF METHODS OF ANALYSIS OF GYPSUM1

The different analytical methods proposed for the evaluation of gypsum have been subjected to an experimental test. A combination method, consisting of a fusion with KHCO₃ and determination of CaO by KMnO₄ titration, the SO₃ by Andrews method of titration of BaCrO₄ has been found to give very reliable results with the least consumption of time.     

茶多酚提取方法进展

本文综述了国内外现有茶多酚提取方法的现状以及近期的研究进展，并对其优缺点进行了评价。这将有助于中低档茶的综合利用和茶多酚的进一步开发应用。     

HEASUREHENT OF INSTANTANEOUS RATES OF LOSS OF VOIATILE COMPOUNDS DURING DRYING OF DROPS

A novel technique serves to monitor instantaneous rates of loss of a volatile solute from a suspended drop during drying. A highly sensitive electron capture detector is used to monitor concentrations of SF6 released into a flowing gas stream from a suspended, drying drop. Simultaneously, the appearance and morphological development of the drop are monitored with a video camera. This provides the wherewithal of relating instantaneous rates of loss of the volatile solute to particular events during the development of particle morphology.

Initial experiments have been carried out with drops of aqueous solutions of glucose, sucrose, maltodextrin and coffee extract. The results clearly display the onset of the volatiles-retentive selective diffusion phenomenon. There is also substantial loss of the volatile component later in the drying process, when the drops undergo repeated ex ansion, bursting and cratering due to the formation of internaf bubbles. These experiments appear to be the first quantitative demonstration of major losses accompanying changes in drop morphology.     

氢气纯度分析方法准确性的探讨

ONACCURACYOFANALYSISOFOFHYDROGEN1前言我公司目前应用的氢气纯度分析方法有两种,一种是爆炸反应法,另一种是焦性没食子酸吸收法。几年来,人们对两种分析方法的准确性曾有过褒贬不一的评论。这里我们也谈谈自己粗浅的观点。2爆炸法测定氢气纯度一定量的氢气样品与适量的空气之均匀混合物因反应后生成液体水而引起气体体积减少,减少的体积等于参加反应气体体积之和。其中l／3为氧气,2／3为氢气。根据氢气取样量和反应前后混气体体积之差,以及氢气在反应中的体积比例关系,可计算出样品的氢气纯度。计算公式式中：A一混…     

SEDIMENTATION OF BINARY MIXTURES OF PARTICLES OF UNEQUAL DENSITIES AND OF DIFFERENT SIZES

A model is developed for the sedimentation from a suspension of two particle species of unequal densities and of different sizes. The composition and the thickness of various layers in the sediments are predicted using graphical and analytical methods. The model predictions were in excellent agreement with experimental results, when the particle size ratio was ≥ 108. When size ratio of the particles was 2.60 and 4.31 the agreement occurred in about 50 percent of the cases.     

环氧树脂羟基值测定方法的研究

利用乙酸酐、吡啶和浓硫酸混合的乙酰化试剂测定环氧树脂中羟基值含量的方法具有操作简便、滴定终点明显和分析结果误差小等优点。     

骑式摩托车油箱喷涂工艺的改进

面对日益激烈的市场竞争,摩托车油箱外观质量越来越成为影响销售的因素之一。文章介绍了改进工艺后的油箱涂装,该涂装体系提高了油箱外观的丰满度,降低了油箱涂装的生产成本。     

ANALYSIS OF RECENT MEASUREMENTS OF THE VISCOSITY OF GLASSES

Viscosity of Simple Soda-Silicate 500° to 1400°C Comparison of the results given by English with those of Washburn, Shelton and Libman, indicates a discrepancy in the absolute values of log₁₀ viscosity amounting to 0.6, those of Washburn et al., being relatively too high. If correction for this is made, the isothermal curves of log₁₀ viscosity as a function of soda content are smooth up to 50% Na₂O, showing no inflection. The observations as a function of temperature T are all represented within accidental error by an equation of the type where all three constants vary regularly with the composition. Change of Viscosity of Glass (6SiO₂, 2Na₂O) due to Molecular Substitution of CaO, MgO and Al₂O₃ for Na₂O The effect is clearly brought out by plotting (from the results of English) the change of log₁₀η due to the substitution as a function of temperature. The curves each show a sharp bend at a temperature between 840° and 1050°C, which is designated the aggregation temperature T_a. If we divide these curves by the corresponding percentage substituted, we get curves for each oxide which are straight and parallel below the aggregation temperatures, the slopes (increase of change of log₁₀η per 100°C) being −0.056 (CaO), −0.055 (MgO), −0.018 (A1₂O₃) per per cent oxide substituted. For substitution of 1/2 molecule the slopes are −0.325 (CaO), −0.23 (MgO) and −0.18 (Al₂O₃) per 100°. At the aggregation temperature the change of log₁₀η per per cent is a minimum, 0.03 to 0.06 for CaO, 0.12 for MgO, 0.07 for Al₂O₃. Evidence of Aggregation in Glasses, from viscosity Measurements The sharp bends in the plots of change of log₁₀η due to substitution of an oxide for Na₂O, suggest the beginning of molecular aggregation at these temperatures. These aggregation temperatures are close to the devitrification temperatures, but the effect on the viscosity curves cannot be due to actual devitrification since it does not change with time. Taking the aggregation temperatures as equal to devitrification temperatures, additional isotherms are roughly sketched into the equilibrium triangle of the system Na₂O-CaO-SiO₂. Change of Viscosity of Glass (4SiO₂, 2Na₂O) due to of Substitution of B₂O₃ for SiO₂ The change of log₁₀η (from the results of English) is plotted as a function of temperature, and also the change of log₁₀η per per cent B₂O₃. The curves are more complex than for the substitution for Na₂O.     

典型煤碳燃烧特性研究和数值模拟

本文以三种典型煤的碳燃烧为研究对象，分别采用简单一维沉降燃烧方式和等温加热燃烧方式，实验研究了煤在快速加热条件下，其碳的初期和中，后期燃烧过程。以实验为基础，建立了煤的碳燃烧模型，变工况数值模拟了煤的碳燃烧过程，揭示了煤不同条件下的单颗粒碳燃烧特性。     

用两个形状指数表征粉煤灰颗粒形貌的研究

引用两个形状指数表征颗粒形状的概念,即先将颗粒形状近似为椭圆,再将椭圆图像分离:以圆为基准的颗粒宏观形状指数δ;以光滑椭圆为基准的颗粒轮廓凹凸度,即微观形状指数ζ。分析和发展了近似椭圆模型。并运用图像分析仪对粉煤灰、水泥样品进行实验。结果表明,粉煤灰颗粒的两个形状指数δ和ζ都大于水泥颗粒。证明粉煤灰颗粒的球形度、表面光滑度优于水泥,而且,随着粒径增大,δ和ζ呈下降趋势,表明磨制颗粒越粗。(?)粒形状越不规则。文中还运用近似椭圆模型再现了颗粒的模拟图像。