等离子体淀积二氧化硅的抗电特性

文章报道了等离子体二氧化硅的抗电特性研究,并指出生长温度和退火条件对抗电特性有直接影响。

Study on mutual impedance characteristics between probes in a circular waveguide

The expression of mutual impedance between two probes in a circular waveguide is derived by means of a vector potential function, reaction concept and reciprocity theorem. The waveguide is semi-infinite, and one end of the waveguide is terminated to a load with a reflection coefficient. The contribution to the mutual resistance is found to come from the dominant mode, while the contribution to the mutual reactance comes from the dominant mode and the higher order modes. The major contribution to the mutual reactance is from the dominant mode, since the higher modes decay rapidly with the increasing the probes’ of separation distance. However, as the separation distance approaches zero, the higher modes become dominant, which results in a large value of the mutual reactance. The mutual impedance is dependent on the location and height of the probes, their separation distance and the location of the terminal plane.

Electrodeposition behavior and characteristics of Ni-carbon nanotube composite coatings

Ni-CNT (carbon nanotube) composite coatings were processed by electrodeposition and their hardness and corrosion characteristics were investigated with variations of CNT concentration in an electrolyte solution and electrodeposition current density. With increasing the CNT concentration in the electrodeposition bath and the current density, more CNTs are incorporated into Ni matrix. Hardness values of the Ni-CNT coatings are irrelevant to the CNT concentration in the solution, the current density, and current mode, implying poor adhesion of CNTs to Ni matrix. With increasing the CNT content in the coating, the corrosion resistance of the Ni-CNT composite coating becomes inferior due to the porous microstructure.

Characterization of alternating current impedance properties of biomedical electrodes

To study the alternating current （AC） impedance properties of Ag/AgC1 electrocardiograph （ECG） electrodes, the electrode pair was gel-to-gel connected, and then the electrical potential was recorded after a safe stimulating current passes through the electrode pair, so the AC impedance data of ECG electrodes were obtained. Varying the frequency and value of stimulating current, the detailed comparison and analysis of AC impedance properties of the electrodes were performed, and the stability was further characterized by using the continuous measurement within 24 h. The experimental results show that the AC impedance values of electrodes decreased, and then slightly increased with the increase of frequency of stimulating current. The minimum AC impedance value was obtained when the frequency was changed to 10 kHz. When the stimulating current increased, the AC impedance values of electrodes showed a slight decrease, but did not change significantly. Besides, the continuous measurement results show that the impedance value presented a significant increase in the initial 30 min, and then was stabilized in the following measuring process.

The Study of the Varying Characteristics of Cathodic Regions for Defective Coating in 3.5% Sodium Chloride Solution by EIS and WBE

The current distributions over carbon steel under iron red alkyd primer exposed to 3.5% sodium chloride solution were mapped using the wire beam electrode （WBE）. The electrochemical impedance spectroscopy （EIS） of the WBE was carded out to analyze the performance of coating delamination and corrosion behavior of carbon steel beneath defective coating. The EIS data revealed that protective capability of coating decreased with immersion time and the degree of cathodic delamination showed a rapid rise. The current density distribution of WBE indicated that cathodic sites was located at the defect at the beginning of immersion and gradually spread into the intact coating. The cathodic regions were distinguished from the anodic area and distributed over the WBE. The changes of cathodic sites could reflect the deterioration process of defective coating. The cathodic area ratio was a more useful parameter than the cathodic delamination degree to evaluate the coating cathodic delamination. The polarity reversals of electrodes at the defect and beneath coating were observed. A simple discussion of relationship between the blister and the polarity reversal was made from a standpoint of electrochemical distribution. WBE method was able to map and record the changes of local cathodic sites beneath defective coating in real time, which could provide more detailed information about the local degradation of coating.

Cold-Test Experimental Research of an S-Band Broadband High Power CCTWT

Cold-test experiment of an S-band broadband high power coupled-cavity traveling-wave tube(CCTWT)is introduced in this paper.The dispersion characteristic,the synchronous voltage and the interaction impedance of this S-band CCTWT are measured.The experimental results are in agreement with the numerical simulation values.

Electrochemical methods for the characterization and interfacial study of dye-sensitized solar cell

Dye-sensitized solar cell （DSSC） is one of the most rapidly developed solar cells in the past 20 years. Many characterization methods have been employed for further understanding the operational details of the photo- electric conversion in DSSC as well as the evaluation of cell performance. Electrochemical methods have become pow- erful tools for studying the charge transfer and interfacial process. In this review, we introduce and explain the various electrochemical methods used to characterize and analyze DSSC, including current-voltage （I-V） scan measurement, cyclic voltammetry, electrochemical impedance spec- troscopy, intensity-modulated photocurrent spectroscopy, and intensity-modulated photovoltage spectroscopy. In ad- dition, some applications were provided as samples to elucidate electron transfer kinetics, energy levels and electrocatalytic activity of the materials used in DSSC.