Conductive potassium feldspar/polyaniline composites prepared by in situ chemical polymerization

Conductive potassium feldspar/polyaniline (K-feldspar/PAn) composites were prepared by the chemical polymerization of aniline in the presence of K-feldspar particles using potassium dichromate in an acidic aqueous medium. The effects of K-feldspar particle size, aniline concentration and temperature upon the PAn amount in the composite and the electrical surface resistance of the composites were examined. Electrical conductivity was higher in the composites prepared by the smaller K-feldspar particles in which the PAn yield is low. The microhardness values of K-feldspar/PAn composites increased to a certain PAn content and then decreased. The microhardness of the composites containing PAn in the range of 1–6%, which were prepared by K-feldspar having particle size smaller than 0.125–0.250 nm, was higher that of pure K-feldspar and PAn (0.843 kPa). Scanning electron microscopy (SEM) showed that PAn covered the surface of K-feldspar particles with an unsmooth PAn layer. The characterization of composites was also made by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA).     

Carbon nanotube/polyaniline core-shell nanowires prepared by in situ inverse microemulsion

By the in situ inverse microemulsion, we prepared multi-walled carbon nanotubes/polyaniline composites (MWNTs/PANI). Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed that the nanotubes were coated with a PANI layer. Fourier transform infrared (FT-IR) spectra suggested that the π-bonded surface of the carbon nanotubes (CNTs) interact strongly with the conjugated structure of the PANI shell layer. The thermal stability and electrical conductivity of the MWNTs/PANI composites were examined by thermogravimetric analysis (TGA) and conventional four-probe method. In comparison with the pure PANI, the decomposition temperature of the MWNTs/PANI (1 wt% MWNTs) composites increased from 360 to 400 °C and the electrical conductivity of MWNTs/PANI (1 wt% MWNTs) composites was increased by one order of magnitude.     

Thermoelectric properties of Bi_(0.5)Sb_(1.5)Te_3/polyaniline composites prepared by mechanical blending and in-situ polymerization

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｒｍｏｅｌｅｃｔｒｉｃｍａｔｅｒｉａｌｓａｒｅｕｓｅｄｔｏｃｏｎｖｅｒｔｔｈｅｒｍａｌｅｎｅｒｇｙｄｉｒｅｃｔｌｙｔｏｅｌｅｃｔｒｉｃｅｎｅｒｇｙｏｒｉｎｒｅ ｖｅｒｓｅ[1～ 4 ] .Ｔｈｅ ｐｅｒｆｏｒｍａｎｃｅｏｆｔｈｅｔｈｅｒｍｏｅｌｅｃｔｒｉｃｍａｔｅｒｉａｌｓｉｓｄｅｔｅｒｍｉｎｅｄｂｙｔｈｅＳｅｅｂｅｃｋｃｏｅｆｆｉｃｉｅｎｔα ,ｔｈｅｅｌｅｃｔｒｉｃｃｏｎｄｕｃｔｉｖｉｔｙσ ,ａｎｄｔｈｅｔｈｅｒｍａｌｃｏｎｄｕｃ ｔｉｖｉｔｙκ ,ｏｒｂｙｔｈｅｉｒｃｏｍ…     

Synthesis of polyaniline/camphor sulfonic acid in formic acid medium and their blends with polyamide-6 by in situ polymerization

Blends of polyaniline doped with camphor sulfonic acid (PAni.CSA) and polyamide 6 (PA6) were prepared for the first time by the in situ polymerization of aniline in the presence of a solution of PA6 in formic acid. The conductivity values of the blends prepared by both solution cast and in situ polymerization are in the range useful for electrostatic charge dissipation materials. The conductivity of the blend containing 10% of PAni.CSA was higher, when the in situ polymerization process was used, indicating the formation of conducting pathways in a higher extension. Most of the blends prepared by the in situ polymerization presented only one irreversible peak in the cyclic voltammetry, which is attributed to the presence of defects along the PAni.CSA chains. These defects may be caused by the presence of formic acid as the solvent, as observed by Fourier transformer infrared spectroscopy of the pure polyaniline prepared in the presence of formic acid.     

Ti-BN粉末冶金原位制备Ti(N)-TiBw复合材料

本文以纯Ti粉末和BN粉末为原料,采用放电等离子烧结技术(SPS)通过原位反应制备了Ti(N)-TiBw复合材料,研究了退火温度对Ti(N)-TiBw复合材料显微组织演化和力学性能的影响。结果表明:在1000 ℃进行烧结时,Ti与BN发生原位反应生成了TiBw和N固溶复合增强钛基复合材料。TiBw以针状形式呈网络状分布于一次颗粒边界处,随着热处理温度的升高,TiBw的长径比先增大后减小,在1100 ℃时达到最大值。而在1100 ℃以上退火处理时,TiBw逐渐发生粗化,微观形貌从针状变成短棒状,其对基体的钉扎效果明显减弱,Ti基体晶粒尺寸逐渐粗化,TiBw的形貌演变遵循Ostwald熟化机制。随着热处理温度的升高,材料的强度先提高后降低,在1000 ℃达到最大值,为908 MPa。材料强度的提升归因于晶粒细化、TiBw载荷传递和O/N的固溶强化。     

Overlapping large polaron tunneling conductivity and giant dielectric constant in Ni0.5Zn0.5Fe1.5Cr0.5O4 nanoparticles (NPs)

We report an orderly study on the structural and dielectric properties of Ni_0.5Zn_0.5Cr_0.5Fe_1.5O₄ nanoparticles (NPs) synthesized by a polyethylene glycol (PEG)-assisted hydrothermal technique. XRD, FT-IR, FE-SEM and EDX measurements were implemented for the structural, morphological and compositional investigations of the product. Dielectric spectroscopy was used for the dielectric property investigation of the sample. Average particle size of the nanoparticles was estimated using Debye-Scherrer's equation as 34 nm. Electrical properties of the sample have been investigated in the range of 1 Hz to 3 MHz (233-412 K). It is observed that the sample has a giant dielectric constant approaching to 10⁶ within the examined temperature range. It is also determined that the sample exhibits a dispersive phase transition around 305 K at which this giant value of dielectric constant has been obtained. This transition has been characterized by Diffuse Phase Transition. Temperature and frequency dependence of dielectric loss function has been attributed to surface charges for the short-time relaxations and to hopping electrons for the long-time relaxations. At low frequencies, dielectric loss function has been supported by the modified Cole-Cole equation. Frequency and temperature dependent conductivity behavior of the sample has been explained by Overlapping Large Polaron Tunneling model.     

原位反应热压SiCp/MoSi2复合材料的组织与性能

以Mo粉、Si粉和C粉为原料,采用原位反应热压一次复合工艺制备不同含量SiC颗粒增强的SiCp/MoSi2试样,并研究其室温抗弯强度、断裂韧性、相对密度以及显微组织。结果表明,原位反应热压一次复合工艺制备的SiCp/MoSi2复合材料的强韧性比纯MoSi2有了大幅度的提高,当SiC含量为40vol%时,SiCp/MoSi2复合材料的抗弯强度达到最大,为475.2MPa,当SiC含量为50vol%时,复合材料的断裂韧性达到最大,为5.45MPa.m1/2。原位形成的SiC使MoSi2基体晶粒得到明显细化,并减少和消除了脆性的SiO2玻璃相。SiCp/MoSi2复合材料强韧性的提高主要是由于晶粒细化、SiC颗粒弥散强化以及脆性SiO2玻璃相的减少和消除。     

Insoluble poly(anthranilic acid) confined in Nafion membrane by chemical and electrochemical polymerization of anthranilic acid

Self-doped polyaniline (PANI) possesses superior electrochemical properties and processability in relation to the PANI due to an acid group substituted on the polymer backbone. However, the polar acid group causes the self-doped PANI to undergo dissolution in aqueous, in particular, acidic solutions. To prevent the solubility, poly(anthranilic acid), PANA, is confined in the cavities of the Nafion membrane by a novel electrochemical as well as a conventional chemical polymerization of anthranilic acid. The PANA is characterized by electrochemical, optical, spectroscopic and scanning electron microscopic studies.     

铝熔体中添加NH4Al(SO4)2制备Al/Al2O3复合材料

向铝熔体中添加脱水的硫酸铝铵,于900℃下发生分解反应,反应分解的Al2O3原位生成颗粒增强铝基复合材料。SEM观察表明,Al2O3颗粒在铝基体中细小弥散分布,形成球形的、不团聚的增强体颗粒。与基材相比,Al/Al2O3复合材料的耐磨损性能明显提高,耐磨性是基材的4倍,且由硫酸铝铵原位生成的复合材料耐磨性优于添加氧化铝形成的复合材料。拉伸实验结果显示,复合材料的抗拉强度没有明显变化,且塑性有所降低。     

添加NH_4AlO（OH）HCO_3原位生成Al_2O_3/Al复合材料的制备及其性能

碳酸铝铵与熔融的铝液反应原位生成颗粒增强铝基复合材料,对复合材料的力学性能和摩擦磨损行为进行研究。结果表明：在搅拌的铝熔体中碳酸铝铵发生分解反应生成γ-Al2O3;该原位反应的增强颗粒比直接添加的Al2O3在铝熔体中分布得更均匀;复合材料的密度和硬度随着增强相加入量的增加而提高,而强度则随着增强相加入量的增加而降低;磨损率随着增强相加入量的增加和载荷的增加而提高;原位反应生成的复合材料的力学性能和耐磨性明显优于直接添加Al2O3颗粒形成的复合材料的。     

占空比对高频脉冲电沉积( Ni-Co) / 纳米 Al2O3复合镀层的影响

采用高频脉冲电沉积法制备(Ni-Co)/纳米Al2O3复合镀层,研究了占空比对复合镀层沉积速率、成分、形貌及表面显微硬度的影响。结果表明:随着占空比由0.3提高至0.5,复合镀层的沉积速率增加,晶粒尺寸变大,表面变粗糙,并且Co含量降低,Ni含量增加,纳米Al2O3颗粒含量变化不明显,Co含量的降低导致硬度降低。     

Corrosion inhibition of mild steel in 1 M HCl solution by henna extract: A comparative study of the inhibition by henna and its constituents (Lawsone, Gallic acid, α-d-Glucose and Tannic acid)

The inhibitive action of henna extract (Lawsonia inermis) and its main constituents (lawsone, gallic acid, α-d-Glucose and tannic acid) on corrosion of mild steel in 1 M HCl solution was investigated through electrochemical techniques and surface analysis (SEM/EDS). Polarization measurements indicate that all the examined compounds act as a mixed inhibitor and inhibition efficiency increases with inhibitor concentration. Maximum inhibition efficiency (92.06%) is obtained at 1.2 g/l henna extract. Inhibition efficiency increases in the order: lawsone > henna extract > gallic acid > α-d-Glucose > tannic acid. Also, inhibition mechanism and thermodynamic parameters are discussed.