Surface Specific Resistance Research Articles

Effect of CeO2@Ni on the Oxidation Resistance of in Situ TiC/Ni Composite Applied for Intermediate Temperature Solid Oxide Fuel Cell Interconnects

The TiC/Ni composites with different CeO2 or CeO2@Ni content are fabricated by pressureless reactive sintering, and the CeO2@Ni particles are prepared by electroless plating technique. The results show that the continuous Ni layer is prepared on CeO2 particles, leading to the decrease of contact angle between CeO2 and Ni from about 116° to 65°. The relative density of composites with 1 wt% CeO2 increases from 85.79% to 96.45% by Ni layer on CeO2 particles. The CeO2 or CeO2@Ni particles exhibit no obvious influence on the microstructure of composites, and Ce atoms of CeO2 diffuse into TiC particles during the reactive sintering process. The mass gain of composite decreases from 7.4709 to 4.9075 mg cm−2 by addition of 1 wt% CeO2@Ni. The Ce‐doped in NiO and TiO2 would restrict the inward diffusion of O atoms and outward diffusion of Ni atoms, resulting in the improvement of oxidation resistance of composite. With the increase of CeO2@Ni content from 0 to 1 wt%, the surface specific resistance of composite decreases from 3.16 to 0.56 Ω cm2 at 800 °C due to the thinner oxide scale and lower bandgap of TiO2 by Ce doping.

Microstructure and Properties of Thin-Film Submicrostructures Obtained by Rapid Thermal Treatment of Nickel Films on Silicon

Nickel films of 40 nm thickness were obtained by means of magnetron sputtering on a single-crystalline silicon substrate. The films were subjected to rapid thermal treatment (RTT) for 7 s until the temperature increased from 200 to 550 °C. By means of the X-ray diffraction method, the structural-phase composition of nickel films before and after RTT was explored. The atomic force microscopy method due to direct contact with the surface under study, made it possible to accurately define the microstructure, roughness, specific surface energy and grain size of the nickel films before and after RTT, as well as to establish the relationship of these parameters with the phase composition and electrical properties of the films. Surface specific resistance was measured using the four-probe method. Based on XRD results, formation of Ni2Si and NiSi phases in the film was ascertained after RTT at 300 °C. At RTT 350–550 °C, only the NiSi phase was formed in the film. The microstructure and grain size significantly depend on the phase composition of the films. A correlation has been established between specific surface energy and resistivity with the average grain size after RTT at 350–550 °C, which is associated with the formation and constant restructuring of the crystal structure of the NiSi phase.

Study on Microstructure and Corrosion Properties of Ag-Ni-Co Alloy Electrodeposited in Low Eutectic Solvent

The Ag-Ni-Co alloy coating is prepared in the low eutectic solvent system by pulsed power supply technology. Infrared spectroscopy and cyclic voltammetry are used to confirm that the addition of metal salts does not change the low eutectic solvent system. When the current density is 1 A/dm2 and the plating time is 40 min, the plating grain is mainly spherical; the coating is uniform and dense. After testing, the surface-specific resistance of the plating is only 1.295 mΩ·cm2, the microhardness reaches 214.8 HV, and the wear rate reaches 3.1. The corrosion resistance of the plating and the substrate is analyzed by a combination of macroscopic electrochemistry and microarea electrochemistry, and the results show that the corrosion potential of the plating reaches −0.141 V, and the corrosion current density reaches 1.299 × 10−7 A/cm2. The corrosion resistance of the plating is much greater than that of the substrate.

Study on microstructure and physical properties of Ba0.5Sr0.5Fe1−xCuxO3−δ–Ce0.8Sm0.15Ca0.05O1.875 cathode materials used in solid oxide fuel cell

Ba0.5Sr0.5Fe1−xCuxO3−δ (BSFCu) and BSFCu–Ce0.8Sm0.15Ca0.05O1.875 (SCDC) were prepared by solid-state reaction and sol-gel method, respectively. The possibility of BSFCu−SCDC composites as cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs) was investigated. The results show that BSFCu has a cubic BaFeO3 structure and no secondary phase. BSFCu−SCDC has cubic BaFeO3 and Ce0.8Sm0.2O1.9 structures, and BaCeO3 secondary phase. The polarization surface specific resistance (ASRRP) of BSFCu increases with increasing Cu doping. For BSFCu–SCDC, 7BSFCu10–3SCDC has the smallest ASRRP (0.106 Ω cm2, 800 °C) at 800 °C–750 °C; at 600 °C − 700 °C, 6BSFCu10–4SCDC has the smallest ASRRP (1.043 Ω cm2, 600 °C). The maximum exchange current densities of 7BSFCu10–3SCDC and 6BSFCu10–4SCDC are about 0.219 and 0.083 A cm−2 at 800 °C and 700 °C, respectively. Compared with BSFCu, 6BSFCu10–4SCDC has a lower overpotential, which shows better electrocatalytic activity, so it can increase the energy efficiency when applied to IT-SOFC.

Study of electrothermal properties of silver nanowire/polydopamine/cotton-based nanocomposites

In this study, cotton fabrics were reported to be typically functionalized by loading silver nanowires (AgNW) on the surface of the polydopamine modified cotton fabric. Firstly, AgNW were prepared by a polyol method and then a polydopamine-modified cotton fabric was prepared by being immersed in AgNW dispersion by the dip-coating method. The resulting silver nanowire/polydopamine/cotton-based nanocomposites (APCN) has a surface specific resistance as low as 2.4 Ω and has good durability and flexibility. In addition, the electrothermal properties of APCN were investigated by applied voltage. The result showed that the composite material can reach 80 °C in a short time under the voltage of 1.8 V, and conform to the power balance model. The steady-state temperature of the composite material is closely related to the voltage, and has a quadratic relationship with the voltage and expresses linear relation with the electric power.

Features of the Radiation-Stimulated Hydrogenation of an Aluminum Surface

By the methods of reflection-absorption IR (infrared) spectroscopy, electrical measurement and AFM microscopy, the process of the radiation-stimulated hydrogenation of the aluminum surface in the Al/ads n-hexane system under γ-irradiation at room temperate is studied. On the basis of the dose dependence of the Al surface specific resistance, two stages of the hydrogenation process in the absorbed dose range (0.5‒120 kGy) are revealed. It is established that the transition from the first to the second stage is accompanied by a decrease in the electrical conductivity of Al by 35 times and an increase in the hydride-nanolayer thickness by an order of magnitude. AFM studies of the aluminum surface relief showed that radiation-stimulated hydrogenation is accompanied by the formation of carbon-nanotube structures. A possible mechanism for the radiation-stimulated hydrogenation of aluminum is suggested.

Surface Specific Resistivity Measurement and Secondary Ion Mass Spectrometric Study of an Anti-static Agent in Polypropylene Sheet.

In order to understand the mechanism of internal surfactants as anti-static agents on polymer surfaces, surface specific resistivity measurement and secondary ion mass spectroscopy (SIMS) were used for characterization of an anti-static agent containing alkylamine surfactant (DEA) in polypropylene (PP) sheet. In this study, deuterium-labeled DEA was used as a model compound and secondary ions emitted from the labeled isotope were detected. We showed the depth profile and imaging of the DEA on the PP surface. We clarified the anti-static mechanism, and concluded that adding alcohol to the antistatic agents accelerates the ooze and diffusion of DEA, resulting in a high anti-static effect on the PP surface.

Study on Work Function of the {0001} Faces of CdS Crystal. I.

The work function (Ws) of the chemically etched {0001} face of a CdS crystal in vacuum and changes of Ws caused by the exposure of crystal faces to air are determined with the Kelvin method. The Ws of a crystal which is photoconductive and has a high surface specific resistivity of the order of 1010∼1013 Ω/□ exhibits the relationships Ws(Cd face)>Ws(S face) in a vacuum of 10 µ Torr and Ws(Cd face)≃Ws(S face) in air. In comparison, the Ws of a crystal which has a relatively low surface specific resistivity of the order of 103∼107 Ω/□ exhbitis the relationship Ws(Cd face)<Ws(S face) in vacuum as well as in air, although the difference between the two is smaller than that in the case of high resistivity crystals. Moreover, abrupt exposure of the surface of a high resistivity CdS crystal to air in the dark immediately causes a large change in the contact potential difference between CdS and Au. The direction of this change depends without exception upon the difference in the polarity.