SiO2微粉加入量对刚玉质超低水泥浇注料高温性能的影响

研究了SiO2微粉加入量为0、2%、4%、6%和8%时对刚玉质超低水泥浇注料的烧结性能、高温强度及抗热震性能的影响.结果表明随着SiO2微粉加入量的增加,试样的烧结性能和抗热震性得到明显改善,在1400℃时的高温抗折强度也显著提高.讨论认为,试样高温性能提高的主要原因是SiO2微粉与Al2O3反应生成的莫来石穿插或弥散在刚玉颗粒形成的骨架结构的孔隙中起增韧作用.     

SiO2微粉和Al2O3微粉加入量对莫来石-刚玉浇注料性能的影响

以莫来石M45(10～5mm,5～3mm)、电熔莫来石(3～1mm,≤1mm)作骨料,刚玉粉(≤0.074mm)、电熔莫来石粉(≤0.074mm)、纯铝酸钙水泥、Al2O3微粉(d50=2.11μm)和SiO2微粉(d50=1.07μm)作基质,制备了脱硫枪用莫来石-刚玉浇注料,并分别研究了SiO2微粉加入量(分别为2%、3%、4%、5%)和Al2O3微粉加入量(分别为2%、4%、6%)对浇注料体积密度、显气孔率、强度、烧后永久线变化率、抗热震性和抗渣性的影响。结果表明:仅加入SiO2微粉时,随着其加入量在2%～5%范围内增加,莫来石-刚玉浇注料的体积密度提高,显气孔率降低,强度增加,抗渣性变好,但抗热震性变差;在加入3%SiO2微粉的基础上再加入2%～6%的Al2O3微粉时,浇注料的各项性能随Al2O3微粉增加没有明显改善,但均比仅加入3%SiO2微粉时有明显改善。     

不同微粉对刚玉质浇注料性能的影响研究

在刚玉质低水泥浇注料中分别引入SiO2微粉和Al2O3/SiO2凝胶粉,研究了试样经烘烤(110 ℃×24 h)和烧成(分别为1100 ℃×3 h和1500 ℃×3 h)后的气孔率、体积密度、线变化率、抗折强度及耐压强度等物理性能.研究结果表明:在刚玉质低水泥浇注料中加入Al2O3/SiO2凝胶粉和SiO2微粉均能有效地降低气孔率,提高其体积密度和强度;但微粉的引入使试样的线变化率增大,且随着热处理温度的提高,影响更加显著.微粉的引入可以有效地改善浇注料中物料的填充行为及烧结行为,从而提高浇注料的密度与强度;在浇注料中加入6wt%的SiO2微粉或6wt%的Al2O3/SiO2凝胶粉可使浇注料获得较好的综合物理性能.     

SiO_2微粉加入量对ρ-Al_2O_3微粉结合刚玉浇注料的影响

在ρ-Al2O3微粉结合刚玉浇注料中分别加入2%和5%的SiO2微粉,制成40 mm×40 mm×160 mm的试样,分别经110℃24 h、1 200 ℃ 3 h和1 500℃3 h热处理后,测定试样的常温抗折强度;在上述配比的基础上去掉其中的骨料,制成15 mm×15 mm×55 mm的基质试样,分别经110℃24 h、1 200℃1 h和1 500℃1 h热处理后,采用扫描电镜分析试样的显微结构.结果表明:1)加入SiO2微粉可以显著提高ρ-Al2O3微粉结合刚玉浇注料在110℃24 h、1 200℃3 h和1 500℃3 h条件下热处理后的常温抗折强度,SiO2微粉加入量以2%(w)为佳;2)SiO2微粉水化后形成网状絮凝结构以及在中高温处理过程中SiO2微粉与ρ-Al2O3微粉反应生成莫来石,是导致含SiO2微粉的ρ-Al2O3微粉结合刚玉浇注料常温抗折强度增大的原因.     

Al2O3微粉及Alphabond加入量对无水泥刚玉质浇注料性能的影响

为了改善刚玉质浇注料的热态强度和抗侵蚀性,采用水合氧化铝Alphabond作为结合剂,分别调整Al2O3微粉及Alphabond加入量,研究了Al2O3微粉及Alphabond加入量对无水泥刚玉质浇注料性能的影响。结果表明:Al2O3微粉加入量对浇注料的成型性能和烧后强度影响较大,其最佳加入量在Alphabond含量(质量分数,下同)为3%时为11%左右;增加Alphabond加入量(在0~4%范围内)可大幅度提高浇注料的烘干强度,但1400℃及1600℃烧后常温抗折强度和1400℃高温抗折强度明显降低。     

热风炉管道用Al_2O_3-SiO_2浇注料性能的影响因素

为了提高热风炉管道用浇注料的使用寿命,以矾土均化料、红柱石颗粒和细粉、白刚玉细粉、纯铝酸钙水泥、SiO2微粉、α-Al2O3微粉、硅溶胶等为原料制备了热风炉管道用Al2O3-Si O2浇注料,并研究了SiO2微粉加入量、骨料类型、水泥加入量以及用硅溶胶作结合剂对浇注料性能的影响。结果表明:1)随着SiO2微粉加入量的增加,热处理后试样的常温抗折强度和常温耐压强度逐步增加,烧后收缩增大,体积密度先增加后降低,综合考虑,SiO2微粉的适宜加入量为4%(w);2)以矾土为骨料的试样具有较高的常温强度和较好的体积稳定性,但以红柱石为骨料时的抗热震性更好;3)结合系统含硅溶胶时,加入纯铝酸钙水泥能降低浇注料的烧后线变化,稍微提高常温强度和抗热震性,而加入柠檬酸则降低试样的抗热震性。     

重油直接裂解制乙烯装置用低密度浇注料的研制

采用大颗粒珍珠岩、矾土熟料、漂珠、SiO2超细粉、Al2 O3微粉为主要原料 ,以纯铝酸钙水泥为结合剂 ,研制了用于HCC装置的低密度浇注料。研究了纯铝酸钙水泥、矾土熟料、SiO2 超细粉、Al2 O3微粉的加入量对浇注料的化学组成、体积密度、耐压强度、抗折强度、烧后线变化率及施工性能的影响。结果发现 :结合剂的最佳掺入量是 2 5 % ,超过 2 5 %后 ,提高结合剂用量反而使浇注料的烧后强度下降 ;低温膨胀剂对浇注料的烧后线变化率影响非常明显 ,低温膨胀剂的最佳掺入量是 5 % ;SiO2 -Al2 O3复合微粉对浇注料烧后强度的增强效果非常显著 ,复合微粉的总量为 8% ,m(SiO2 )∶m(Al2 O3)在 1∶4～ 1∶5范围内 ,浇注料的中温强度能大幅度提高。使用证明 ,研制的低密度浇注料是一种较理想的HCC装置用衬里材料。     

ρ-Al2O3加入量对莫来石-刚玉浇注料性能的影响

以烧结莫来石(w(Al2O3)>45%)、电熔莫来石(w(Al2O3)>70%)、刚玉(w(Al2O3)>99%)、α-Al2O3微粉(w(Al2O3)>99.5%)、SiO2微粉(w(SiO2)>92%)、ρ-Al2O3微粉(w(Al2O3)>83.0%)等为主要原料,制备了莫来石-刚玉浇注料试样,经110℃24 h、1 000℃3 h和1 400℃3 h处理,研究了ρ-Al2O3加入量(w)分别为1%、2%、3%、4%和5%对莫来石-刚玉浇注料性能的影响。结果表明:随着ρ-Al2O3加入量的增加,莫来石-刚玉浇注料的体积密度下降,显气孔率增大,抗热震性和抗渣性逐渐变好。110℃24 h处理后强度逐渐增大;1 000℃和1 400℃处理后强度和永久线变化率则是先增加后减小,当ρ-Al2O3加入量为2%时达最大;试样的高温抗折强度先增加后减小,以ρ-Al2O3加入量为3%时最大。     

SiO_2微粉对水泥结合刚玉质浇注料中低温化学键变化的影响

以电熔棕刚玉(8~5、5~3、3~1 mm)和电熔白刚玉(≤1、≤0.045 mm)为主要原料,添加α-Al2O3微粉和SiO2微粉制备铝酸钙水泥结合刚玉质浇注料,研究了经110、800和1 000℃热处理后含5%(w)Si O2微粉和不含SiO2微粉浇注料基质中化学键变化与浇注料强度的关系。采用XPS和FTIR研究Si O2微粉与水泥水化产物经110℃烘干和800℃热处理后的化学键变化。结果表明,经110和800℃热处理后,SiO2微粉和水泥水化物之间形成了Si—O—Al结合键。因此,在110~800℃,含Si O2微粉的铝酸钙水泥结合浇注料的强度较高的原因是Si O2微粉与水泥水化物之间形成了Si—O—Al化学键。     

二氧化硅和氧化铝微粉加入量对MgO基浇注料流变性的影响

采用电熔镁砂颗粒作骨料,电熔镁砂粉、电熔白刚玉粉、Al2O3微粉和SiO2微粉作基质料,固定骨料与基质料质量比为65:35,且固定基质料中Al2O3微粉与SiO2微粉的总加入量为8%,改变两种微粉的加入比例(Al2O3微粉的加入量分别为8%、6%、4%、2%、0,SiO2微粉的相应为0、2%、4%、6%、8%),分别加6.4%的水制成MgO基浇注料,并采用浇注料流变仪研究了Al2O3微粉与SiO2微粉的加入量对浇注料流变性(扭矩、流动阻力和粘度)的影响。研究结果表明:随着SiO2微粉加入量的增加,浇注料的扭矩、流动阻力和粘度呈降低趋势,但SiO2微粉加入量超过4%后变化很小。     

Full characterization for material constants of a promising KNN-based lead-free piezoelectric ceramic

Potassium-sodium niobate (K_1-xNa_xNbO₃, referred to as KNN) solid solutions, which are an important type of lead-free piezoelectric materials possessing environmentally friendly features, good piezoelectric response and high Curie temperature, have attracted considerable attention in replacing lead-based ceramics. In order to promote the application of KNN-based ceramics in piezoelectric devices, we characterized a complete set of material constants of a high performance KNN-based ceramic, that is 0.965(K_0.48Na_0.52) (Nb_0.96Sb_0.04)O₃-0.035Bi_0.5Na_0.5Zr_0.15Hf_0.75O₃ (KNNS-BNZH), whose Curie temperature is 235 °C, piezoelectric coefficient d₃₃ is 380 pC/N and electromechanical coupling factor k₃₃ is 70%. These results will benefit the design of piezoelectric transducers and actuators using lead-free piezoelectric ceramics.     

Mechanical,dielectric, and thermal properties of fluorosilicone rubber composites filled with silica/multiwall carbon nanotube hybrid fillers

In this work, hybrid fillers consist of modified silica (SiO₂) and multiwalled carbon nanotube (MWCNT) were used to improve the mechanical, dielectric, and thermal properties of fluorosilicone (FSR) composites via a direct mechanical mixing method. With the increase of CNT loading in SiO₂/CNT hybrid loading ratio, the tensile properties, dielectric constant, electrical conductivity, and thermal properties all increase without a sharp sacrifice of flexibility. The dielectric constant of FSR-S15/C5 achieved 7,370 @1 kHz, which is about four orders of the FSR-S20, and the dielectric loss remains as low as 0.676 @1 kHz. Therefore, the linkage of SiO₂ and FSR chains not only enhances the interfacial interaction between the fillers and FSR matrix but also decreases the agglomeration of the fillers in matrix. What is more, modified SiO₂ and CNT were designed as the effective hybrid filler to improve the performance of the polymeric matrix through synergic effect.     

High magnetic and ferroelectric properties of BZT-LSM multiferroic composites at room temperature

In this research, the effects of La_0.7Sr_0.3MnO₃ additive on the phase evolution, microstructure, dielectric, ferroelectric and magnetic properties of BaZr_0.07Ti_0.93O₃ ceramics were systematically investigated. The (BaZr_0.07Ti_0.93O₃)/x(La_0.7Sr_0.3MnO₃) or BZT/xLSM (where x?=?0, 5, 10 and 20?mol%) ceramics were prepared via a solid state reaction method. A pure perovskite phase is observed for the samples of x?≤?10?mol%. The M-H hysteresis loops also show an improvement in the magnetic behavior for higher LSM content samples as well as the modified ferroelectric properties. However, the 5?mol% sample exhibited the optimum ferroelectric and ferromagnetic properties with remnant magnetization (M_r) and remanent polarization (P_r) of 2.38?emu/g and 10.5?µC/cm², respectively. The dielectric-temperature curves show that the two phase-transition temperatures as observed for the unmodified BZT ceramic merges into a single phase-transition temperature for the 5?mol% sample and then become flat curves for the 10?mol% sample. In addition, the mechanical properties i.e. Knoop hardness and Young's modulus values increase with increasing LSM content, where Knoop hardness and Young's modulus values for the 20?mol% sample are increased by ~ 45% and ~ 104%, respectively, as compared to the unmodified sample.     

PVDF piezoelectric voltage coefficient in situ measurements as a function of applied stress

Direct piezoelectric g₃₁ voltage coefficient was measured in situ as a function of applied tensile stress for films of polyvinylidene fluoride (PVDF). Measurements were performed under quasi‐static conditions with applied strain rates of 0.5–1.5 mm/min for strains up to 12%. Open‐circuit voltage was measured with a contact‐less electrostatic voltmeter. Obtained results show a strong dependence of the g₃₁ coefficient of mono‐oriented PVDF films on the applied stress, with a maximum value of the coefficient in the transition region between elastic and plastic deformation zones. The effect of sample geometry on the apparent g₃₁ coefficient is shown and discussed. The anisotropy of the piezoelectric effect is studied by means of g₃₁ and g₃₂ measurements. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43248.     

Investigation of dielectric and piezoelectric properties in aliovalent Eu3+-modified Pb(Mg1/3Nb2/3)O3-PbTiO3 ceramics

Rare earth (Eu³⁺)-modified Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PMN-PT) polycrystalline ferroelectric ceramics were fabricated by high-temperature solid-state sintering, the phase structure, dielectric and piezoelectric properties were investigated. Eu³⁺ addition was found to significantly improve dielectric and piezoelectric properties of PMN-PT, where the optimized properties were achieved for the composition of 2.5 mol%Eu: 0.72PMN-0.28PT, with the piezoelectric d₃₃ = 1420 pC/N, dielectric ε_r = 12 200 and electromechanical k₃₃ = 0.78, respectively. All these results indicate that the Eu³⁺-doped PMN-PT ceramics are promising candidates for high-performance room-temperature piezoelectric devices.     

The effect of the Zn/Sn ratio on the formation of single phase kesterite Cu2ZnSnS4 solar cell material

The effect of the Zn/Sn ratio in the solution on the properties of Cu₂ZnSnS₄ films prepared by sol-gel method has been investigated. As the Zn/Sn ratio in the solution increases to a certain value, a pure single phase kesterite CZTS is obtained and confirmed by XRD, XPS and Raman. Through controlling the Zn/Sn ratio in the solution, secondary phases such as SnO₂ can be avoided and an optimal condition for single phase kesterite CZTS can be achieved. Surface SEM images of the CZTS films are investigated and the optical band gap of the optimized CZTS film is found to be 1.23 eV.     

Modification of chitosan-Fe3O4 microspheres with isophorone diisocyanate and formation of polyurethane/mchitosan-Fe3O4 antimicrobial polymer

Polyurethane/modified chitosan-Fe₃O₄ (PU/mCS-Fe₃O₄) nanocomposites were prepared by incorporating chitosan-Fe₃O₄ (CS-Fe₃O₄) into PU through chemical grafting using isophorone diisocyante (IPDI). The isocyanate group of IPDI was introduced on the surface of CS-Fe₃O₄ nanocomposites. The chemical functionalities of the CS-Fe₃O₄ and mCS-Fe₃O₄ were verified by Fourier-transform infrared and X-ray diffraction. The structure and properties were confirmed by scanning electron microscope, vibrating sample magnetometer, thermogravimetric analysis, atomic force microscope, and tensile testing. The experimental results indicate that thermal stability, tensile strength, and storage modulus of nanocomposites were improved with the increasing content of mCS-Fe₃O₄. Meanwhile, PU/mCS-Fe₃O₄ nanocomposites have less cytotoxicity and good antibacterial activities againstEscherichia coli and Staphylococcus aureus.     

Synthesis,properties, and dyeing application of nonionic waterborne polyurethanes with different chain length of ethyldiamines as the chain extender

This study deals with the synthesis of some nonionic waterborne polyurethanes (PUs), using ethyldiamines of different chain length, such as ethylenediamine (EDA) and diethyltriamine (DETA), as the chain extender in the reaction, and examines the thermal properties, mechanical properties, and dyeing properties of the PU products and their blends. As far as each PU by itself is concerned, we found that the T_g of the one made with DETA is the highest, followed by that with EDA, and the one with 1,4‐butanediol (1,4‐BD) is the lowest. The PU made with 1,4‐BD as the chain extender has no T_m, while the two others, using diamines as chain extenders, have a clear T_m, the one with DETA being higher than that with EDA. However, the enthalpy data are just the opposite. The tensile strengths of the two PUs, made with diamines as the chain extender, are larger than that made with 1,4‐BD, but their respective elongation properties are just the opposite. A comparison within PUs made with diamines showed that the one made with EDA is greater in both strength and elongation categories than that made with DETA. However, the one made with DETA is far superior to both of those made with 1,4‐BD and EDA in their dye‐exhaustion ratio, color yield (K/S), fixation rate, and color fastness. In respect to the various PU mixtures that we examined, we found that both PUs synthesized with EDA or DETA as the chain extender would have their T_g's greatly increased by blending in some PU made using 1,4‐BD as the chain extender. Among them, in particular, a blend of PU, made separately with DETA and 1, 4‐BD as the chain extender, showed great improvements in both tensile strength and elongation and also demonstrated better dyeability. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2824–2833, 2003     

铅酸蓄电池用胶黏剂性能对比

为了解决阀控密封铅酸蓄电池的密封问题,通过对AB胶、3114AA、3114C的机械性能、化学性能、物理性能的对比实验,认为：AB胶在对ABS的粘接强度、固化速度方面都要优于3114AA和3114C,同时它的价格也便宜,因此,我们选用AB胶作电池盖与槽密封的胶黏剂;而3114AA、3114C在对金属铅的粘接强度、耐硫酸腐蚀方面都优于AB胶,同时3114AA较3114C具有固化时间更短、对ABS的粘接强度更高、耐硫酸腐蚀能力更强、可以常温固化等优点,因此,我们就用3114AA作电池极柱密封的胶黏剂。     

瓶罐玻璃生产关键工艺性能测量方法与应用

综述了瓶罐玻璃生产制备过程中的关键工艺性能的测量表征方法和适用的仪器设备。涉及的关键工艺性能主要包括熔解特性、熔体特性和温黏特性等。熔解特性的分析包括原料成分分析、粒度分析、熔化均匀性分析、澄清分析等;熔体特性的测量包括表面张力测量、高温电阻率测量、羟基含量测量等;温黏特性测量主要包括高温黏度(熔融温度T_m、工作点T_w、液相线T_L)测量、中温黏度(软化点T_s)测量、低温黏度(膨胀软化点T_d、退火点T_a、转变点T_g和应变点T_st等)测量。上述工艺性能精确测量和表征,对制备高质量瓶罐玻璃制品具有重要意义。