石墨电极和接头的热膨胀系数

1　热膨胀系数对石墨电极和接头来说,热膨胀系数(ＣＴＥ)是一个很重要的质量指标。电极石墨具有很强的各向异性,它们的纵向ＣＴＥ和横向ＣＴＥ大小不同,因而在这两个方向上它们的膨胀行为也不同。石墨电极相关标准规定的ＣＴＥ指标是指纵向ＣＴＥ值,其数值是按照ＧＢ3074.4—82[1]使用石英膨胀仪测定的,测试温度范围为100～600℃,计算公式为[2]:α=ΔＬ/(Ｋ×Ｌ0×Δｔ) 修正系数式中:ΔＬ———试样在100～600℃温度区间的膨胀量,ｍｍ;Ｌ0———试样在室温时的长度,ｍｍ;Δｔ———温升范围,即600℃-100℃=500℃;Ｋ———膨胀仪放大倍数。…     

石墨电极在SEM下的特征

利用SEM（扫描电子显微镜）对石墨电极的显微结构及断口形貌进行了观察分析,探讨了石墨电极的微观结构与其性能的关系,以及微缺陷及其与断裂特性的关系,提出了生产过程中控制和减少微缺陷、提高产品质量的建议措施。     

对我国石墨电极产业集中度的探讨

基于4企业集中度(CR4)、8企业集中度(CR8)和赫尔芬达尔-赫希曼指数(HHI)等指标,对我国石墨电极产业集中度进行了专门测度和判断,并进行了相关讨论。     

我国石墨电极出口现状及思考

介绍了我国石墨电极出口规模、出口创汇、出口地理分布、出口主体、出口结构、出口经营模式以及出口依存度的现状,指出石墨电极在出口经营中存在着战略不清晰、人民币升值削弱出口竞争力以及销售服务跟不上和出口秩序混乱等问题,提出了应对方略.     

吉炭Ф700mm超高功率石墨电极研制成功

由吉林炭素股份有限公司自行研制开发的Ф700mm超高功率石墨电极，于2004年11月份在宝钢集团上海五钢公司100吨直流电弧炉上进行了工业性试验，试验取得了圆满成功。在炼钢厂正常生产条件下，电极各项性能和吨钢电极消耗达到了进口产品水平，表现出了良好的使用效果，完全可以满足用户的使用需求，得到了用户的高度评价。目前随着国内钢厂大型电弧炉的不断增多，     

我国首套趋高功率石墨电极装置建成

从河南省开封炭素有限公司获悉，首套超高功率石墨电极装置在历经20年的论证、融资、工程建设后，于近日在该公司全面竣工。该项目的建成，填补了我国超高功率石墨电极生产的空白，使我国成为继日本、美国、德国之后第四个可生产该产品的国家。     

6万吨石墨电极焙烧合作项目落户首山焦化

8月25日,首山焦化公司与开封炭素公司在首山焦化公司签订6万吨石墨电极焙烧合作项目建设协议,联合组建首山三基炭素公司。     

2014年度石墨电极市场分析

<正>2014年的石墨电极市场一路都以清淡为主,企业人士对于市场的期待终究成殇。在整个市场经济复苏缓慢、总体需求疲软低迷的背景下,各种炭素产品的价格走势一路下行,石墨电极则表现得尤为凸显。转眼间2014年将画上句号,市场多重利空因素难以迅速消弭,国际、国内宏观环境走弱拖累上下游行业仍在延续,石墨电极市场也无法出现质的逆转。整体来看,石墨电极2014年的走势长期处在低谷,笔者以季度为时间段进行详细剖析。2014年一季度,原料石油焦价格基本在持续上行,各石     

石墨电极在黄磷生产中的使用分析

石墨电极在黄磷生产中的使用分析徐宝明，张德明，杨浩林（南通碳素厂南通２２６００２）（南通磷肥厂）１黄磷生产的基本原理黄磷生产有电炉法和高炉法两种。电炉法产品质量好、成本低，高炉法很少采用。电炉法是将磷矿石、焦炭、硅石（破碎成３～２５ｍｍ的粒度），按一...     

凹凸棒土/石墨复合材料电极的制备及性质

以酸化处理的凹凸棒土粉和膨胀处理的石墨粉为原料、环氧树脂为粘合剂,制得凹凸棒土/石墨复合材料电极。采用扫描电镜、红外光谱等对其形貌和结构进行表征。探讨了电极材料类型、富集时间、平行测定次数对模拟苯酚废水峰电流的影响。研究结果表明,凹凸棒土/石墨复合材料电极比普通石墨电极对峰电流的响应更明显,且稳定性好,无二次污染。     

Selective determination of L-dopa in the presence of uric acid and ascorbic acid at a gold nanoparticle self-assembled carbon nanotube-modified pyrolytic graphite electrode

Gold nanoparticle-functionalized carbon nanotubes (AuNP-CNT) have been prepared by a novel self-assembly method. The new material has been characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD) and utilized for constructing AuNP-CNT-modified pyrolytic graphite electrode (AuNP-CNT/PGE) to investigate the electrochemical behavior of L-dopa in neutral phosphate buffer solution. Compared to bare PG electrode, AuNP-CNT/PGE shows novel properties towards the electrochemical redox of L-dopa in phosphate buffer solution at pH 7.0. The oxidation potential of L-dopa shows a significant decrease at the AuNP-CNT/PGE. The oxidation current of L-dopa is about 5-fold higher than that of the unmodified PGE. Using differential pulse voltammetry (DPV) method, the oxidation current is well linear with L-dopa concentration in the range of 0.1-150 μM, with a detection limit of about 50 nM (S/N = 3). The proposed electrode can also effectively avoid the interference of ascorbic acid and uric acid, making the proposed sensor suitable for the accurate determination of L-dopa in both pharmaceutical preparations and human body fluids.     

UHP石墨电极接头糊料及生坯的微观特征

分析描述了超高功率石墨电极接头的糊料、生坯在偏光显微镜下的不同微观结构特征,把分析结果应用于生产实际的工艺改进,并对改进前后的产品进行了对比评价。     

Reaction and nucleation mechanisms of copper electrodeposition on disposable pencil graphite electrode

The reaction and nucleation mechanism of copper electrodeposition on disposable pencil graphite electrode (PGE) in acidic sulphate solution were investigated using cyclic voltammetry (CV) and chronoamperometry (CA) techniques, respectively. Electrochemical experiments were followed by morphological studies with scanning electron microscopy (SEM). The effect of some experimental parameters, namely copper concentration, pH, scan rate, background electrolyte, deposition potential, and conditioning surface of the electrode were described. At the surface of PGE, Cu²⁺ ions were reduced at −250 mV vs. SCE. It was found that electrodeposition of copper is affected by rough surface of PGE. The nucleation mechanisms were examined by fitting the experimental CA data into Scharifker-Hills nucleation models. The nuclei population densities were also determined by means of two common fitting models developed for three-dimensional nucleation and growth (Scharifker-Mostany and Mirkin-Nilov-Herrman-Tarallo). It was found that deposition potential and background electrolyte affect the distribution of the deposited copper. The morphology of the deposited copper is affected by background electrolyte.     

Determination of amiloride using a ds-DNA-modified pencil graphite electrode based on guanine and adenine signals

A sensitive electrochemical procedure based on ds-DNA interaction with amiloride at a ds-DNA-modified pencil graphite electrode (PGE) was introduced as a promising tool for determination of amiloride. An adsorptive stripping voltammetry was applied for the immobilization of ds-DNA on PGE in acetate buffer (pH 4.8). Differential pulse voltammetry (DPV) was carried out to obtain the change in the oxidation signal intensity of guanine and adenine before and after interaction with amiloride. The decrease in intensity of the guanine and adenine oxidation signals was used as an indicator for the sensitive determination of amiloride. Under the optimum conditions, a linear dependence of the guanine and adenine oxidation signals was observed to the amiloride concentration in the range of 0.75-240 μmol L⁻¹ with a detection limit of 0.5 μmol L⁻¹. The relative standard deviations of 10 replicate measurements of 1.0 and 10.0 μmol L⁻¹ amiloride concentrations were 4.7% and 5.3%, respectively. UV-vis measurements combined with DPV were also carried out to propose the most plausible mechanism for the interaction of amiloride and ds-DNA. The influence of potential interfering substances on the amiloride determination was studied. Finally, the ds-DNA-modified PGE biosensor was applied for the determination of amiloride in tablets and urine samples with satisfactory results.     

Preparation and characterization of a graphite electrode containing carbon nanotubes grown in situ by flame synthesis

A crystalline flake graphite electrode (GE) was impregnated with nickel particles using direct current electrochemical deposition. The particles were used for in situ growth of carbon nanotubes (CNTs) by flame synthesis with a liquid ethanol flame. The obtained electrode was characterized by X-ray diffraction, and scanning and transmission electron microscopy. The results showed that the deposited Ni catalyst crystal face was mainly (1 1 1). CNTs with a diameter of about 40 nm were uniformly grown on the GE surface. The electrochemical performance of the CNT–GE was characterized by cyclic voltammetry using a [Fe(CN)6]³⁻/[Fe(CN)6]⁴⁻ solution, and showed a much greater electrochemical response than that obtained using a material in which CNTs were grown by catalytic chemical vapor deposition.     

Voltammetric behavior of nicotine at pencil graphite electrode and its enhancement determination in the presence of anionic surfactant

The electrochemical oxidation of nicotine was studied in aqueous as well as micellar media at a pencil graphite electrode using cyclic, differential pulse and square-wave voltammetric techniques. The compound was oxidized irreversibly at low positive potentials in one (in acidic and neutral media) or two (in alkaline media) oxidation steps. The response was evaluated with respect to pH, scan rate, addition of surfactant and other variables. For analytical purposes, very resolved voltammetric peaks at +0.84 V (versus Ag/AgCl) were obtained in phosphate buffer at pH 7.0 containing 2 mM sodium dodecylsulfate using square-wave mode. The process could be used to determine nicotine concentrations in the range of 7.6–107.5 μM with a detection limit of 2.0 μM (0.33 mg L⁻¹). The proposed method was applied to the determination of nicotine in different brands of commercial cigarettes.     

Electrochemical detection of acetaminophen on the functionalized MWCNTs modified electrode using layer-by-layer technique

A selective electrochemical method is fabricated via layer-by-layer (LBL) method using both positively and negatively charged multi walled carbon nanotubes (MWCNTs) on poly (diallyldimetheylammonium chloride) (PDDA)/poly styrene sulfonate (PSS) modified graphite electrode, for the determination of acetaminophen (ACT) in the presence of dopamine (DA) and high concentration of ascorbic acid (AA). The modified electrode was characterized by cyclic voltammetry (CV) electrochemical impedance spectroscopy (EIS), atomic force microscopy (AFM) and scanning electron microscopy (SEM). Experimental conditions such as pH, accumulation potential and time, effect of potential sweep rates and interferents were studied. In CV well defined peaks for AA, ACT and DA are obtained at 24, 186 and 374 mV, respectively. The separations of peaks were 210, 188 and 398 mV between AA and DA, DA and ACT and AA and ACT, respectively. The diffusion coefficient was calculated by chronocoulometric. Chronoamperometric studies showed the linear relationship between oxidation peak current and concentration of ACT in the range 25–400 μM (R = 0.9991). The detection limit was 5 × 10⁻⁷ mol/L. The proposed method gave satisfactory results in the determination of ACT in pharmaceutical and human serum samples.     

Chiral recognition of tryptophan enantiomers based on a polypyrrole‐flake graphite composite electrode column

A polypyrrole (PPy)‐flake graphite composite was synthesized by in situ polymerization of pyrrole on flake graphite surface, and the resulting organic–inorganic composite material was developed as the conductive stationary phase in an electrode column for enantioselective recognition of tryptophan (Trp) enantiomers. Compared with the stationary phase made up with conducting PPy, the conductivity of the composite stationary phase was enhanced significantly. As a result, satisfactory enantioselectivity of Trp enantiomers can be achieved easily by modulating the potential applied on the electrode column. Various important parameters influencing the performance of the composite electrode column were investigated to obtain the optimum recognition efficiency. A recognition efficiency of 3.7 could be achieved under the optimum conditions. Enantioselectivity of the composite material for Trp enantiomers is attributed to the reversible doping/de‐doping properties of PPy. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012