Composition and Morphology of Zn-Co Alloy Coatings Deposited by Means of Pulse Plating Containing Reverse Current

The influence of bath constituents and pulse parameters on cobalt content, surface morphologies and grain size of Zn-Co alloy deposits was studied using a pulse plating technique with a square- wave current containing reverse pulse, It is found that Zn-Co alloy coatings obtained from the bath with the cobalt ion concentration over 60 wt% have a higher cobalt content in deposits. The results of pulse plating show that the average current density and reverse anodic current density amongst the variables investigated have very strong effects on the cobalt content in the Zn-Co alloy deposits. It is possible to electrodeposit Zn-Co alloy coatings with 10-90 wt% cobalt by modulating pulse parameters. The grain size, surface appearance and internal stress in the deposit were improved significantly by introducing the reverse current.

Pulse Plating of Zn-Co Alloy Coatings

Pulse plating of Zn-Co alloys was studied using square pulse containing reverse current.The surface morphologies of Zn-Co alloy deposits were examined using scanning elecron microscopy （SEM）, and an attendant energy dispersive X-ray analyzer （EDA） was used to analyze the composition of Zn-Co alloy deposits. Results obtained showed that the average current density and reverse current density amongst all the variables investigated had very strong effects on the cobalt content and surface morphologies of Zn-Co alloy deposits. It is possible to elecrodeposit Zn-Co alloy coatings with a very wide cobalt content range of 10-90 wt% by modulating pulse parameters.

Effect of magnetic fields on pulse plating of cobalt films

Magnetic fields parallel to the electrodes were introduced during a pulse plating process to obtain cobalt thin films from alkaline baths. Ef-fects of different magnetic intensities on the composition, microstructure, and magnetic properties of cobalt thin films were investigated. It was found that the deposition speed increased gradually with the increase of magnetic intensity. Almost all of the deposited films were crys-talline and showed Co(002), Co(100) peaks. With the rise on the magnetic intensity, the intensity of Co (002) peak raised gradually. Mag-netic fields would induce cobalt growing along (002) orientation. The films were densely covered with typical nodular structure. Films of smaller grain size and smooth surface could be formed under high magnetic intensity (1 T) as a result of magnetic force and MHD effects. Moreover, higher magnetic intensity induced larger saturation magnetization and lower coercivity. With the rise on magnetic intensity, cobalt contents in the films increased gradually, which led to the rise of saturation magnetization.

Pulse Plating of Copper-ZrB_(2) Composite Coatings

Copper-zirconium diboride （ZrB2） composite coatings were fabricated using pulse plating technique to acquire a new type of EDM （electro-discharge machining） electrode material. The effects of pulse parameters, i.e., the average current density, the frequency and the duty cycle, on the incorporation of ZrB2 particles in the copper matrix were investigated. The amount＇of codeposited ZrB2 particles had a maximum at average current density of 3 A/din2 and increased with decreasing duty cycle as well as current frequency of the pulse current used for deposition. The hardness of the coatings increased with increasing ZrB2 percentage, whereas the incorporation of ZrB2 particles had little effect on the resistivity of the composites.

Effect of direct current and pulse plating on the EDM performance of copper-zirconium diboride composites

Direct current and pulse plating of copper-zirconium diboride （ZrB2） composites were studied and the effects of current density （DC） and pulse duty cycle （PC） on the EDM performance of the composites were investigated. With increasing current density, the effect of grain refinement on the electro-discharge machining （EDM） performance of the composites compensates that of the decrease of ZrB2 content in the composites, which improves the spark-resistance of the material. Under the same average current density and other experiment conditions, a lower duty cycle yields better EDM performance probably because more ZrB2 particles are incorporated in the composites in this condition. However, at a still lower duty cycle （10%）, the particle agglomeration and the microcracks of the copper matrix occur, which considerably deteriorate the spark-resistance of the composites.

Effects of Chloride Ion on the Texture of Copper and Cu-ZrB_(2) Coatings Electrodeposited from Copper Nitrate Solution in Different Plating Modes

For the first time, the texture of copper and Cu-ZrB2 coatings produced from copper nitrate solution was studied. Chloride ion shows different effects on the deposit texture under direct current （DC） and pulse current （PC） conditions. Copper deposits are strongly 〈220〉 textured in DC plating with and without chloride ion. While in PC condition, the predominant texture shifts from 〈220〉 to 〈200〉 as the chloride ion concentration exceeds 20 mg/l. The addition of ZrB2 particles enhances the cathodic polarization of copper deposition, which improves the growth of （111） plane. However, this improvement can be eliminated by further addition of chloride ion.

Design aspect of a novel L-shaped pulsed column for liquid–liquid extraction applications: Energy consumption and the characteristics velocity concept

This article deals with the evaluation of the consumption of energy for a steady state solvent extraction in a novel L-shaped pulsed sieve-plate column, which is highly required for design and optimization of the periodic flow processes for industrial applications. In this regard, a comprehensive evaluation on the energy consumption in case of a pulsed flow for three different chemical systems is conducted and besides the influence of pulsation intensity, the effect of geometrical parameters including the plate spacing and the plate free area is investigated as well. Moreover, the concept of characteristic velocity models at flooding points is evaluated with respect to the variation of pressure drop along the column at different operational conditions.

High-Efficiency Generation of 0.12 mJ, 8.6 Fs Pulses at 400 nm Based on Spectral Broadening in Solid Thin Plates

We demonstrate eftlcient generation of continuous spectrum centered at 40Ohm from solid thin plates. By frequency doubling of 0.8m J, 3Ors Ti：sapphire laser pulses with a BBO crystal, 0.2m J, 33fs laser pulses at 400nm are generated. Focusing the 400-nm pulses into 7 thin fused silica plates, we obtain 0.15mJ continuous spectrum covering 350-450 nm. After compressing by 3 pairs of chirped mirrors, 0. 12 m J, 8.6 fs pulses are achieved. To the best of our knowledge, this is the first time that sub-10-fs pulses centered at 400nm are generated by solid thin plates, which shows that spectral broadening in solid-state materials works not only at 800nm but also at different wavelengths.

METAL SURFACE MODIFICATION──RESEARCH OF BRUSH PLATING TECHNOLOGY OF CrLAYER

Trivalen t Cr layers are studied by direct current brush- plating and pulse current brush-plating. Under the SEM,the appearence,the morphology of cross sections and normal sec- tions of the layers are observed and analysed,the hardness, bond intensities and corrosion- resis- tance are measured. Then, the election- probe and X ray diffraction instruments are used to study the bond and harden mechanism of lavers,The result of research shows that: the harden ef- fect of the layers is caused by the extra- fine grains and internal stress in the layers. And the lay- ers and basis are joined by mechanical bond,metal bond and diffuse bond. All these kinds of bonds lie on different places of interface, they make the layers and base metal unit well.

Effect of Magnetic Field on Properties of AuPt Particles Magneto- electrodeposited on Carbon Paper

AuPt nano particles are bi-functional catalysts for Oxygen Reduction Reaction （ORR） and Oxygen Evolution Reaction （OER） that were taken place on air electrodes in lithium air batteries. Magnetic field has been applied during electrodeposition for the preparation of AuPt particles. With the increase of the magnetic flux density under constant current density, the grain size decreases from - 1μm to 200nm and the activity of the AuPt catalyst increases. The magnetic field oriented vertical to the electric field has a promotion effect on increasing the catalytic ability of AuPt/carbon electrode. By pulse plating, the grain size decreases to about 100nm. By adjusting parameters of the electric field and the magnetic field, controllable in-situ preparation of AuPt catalyst with various morphology and catalytic activity could be achieved.

Effect of dilution rate on dynamic and steady-state biofilm characteristics during phenol biodegradation by immobilized Pseudomonas desmolyticum cells in a pulsed plate bioreactor

Pulsed plate bioreactor （PPBR） is a biofilm reactor which has been proven to be very efficient in phenol biodegradation. The present paper reports the studies on the effect of dilution rate on the physical, chemical and morphological characteristics of biofilms formed by the cells of Pseudomonas desmolyticum on granular activated carbon （GAC） in PPBR during biodegradation of phenol. The percentage degradation of phenol decreased from 99% to 73% with an increase in dilution rate from 0.33 h^-1 to 0.99 h^-1 showing that residence time in the reactor governs the phenol removal efficiency rather than the external mass transfer limitations. Lower dilution rates favor higher production of biomass, extracellular polymeric substances （EPS） as well as the protein, carbohydrate and humic substances content of EPS. Increase in dilution rate leads to decrease in biofilm thickness, biofilm dry density, and attached dry biomass, transforming the biofilm from dense, smooth compact structure to a rough and patchy structure. Thus, the performance of PPBR in terms of dynamic and steady-state biofilm characteristics associated with phenol biodegradation is a strong function of dilution rate. Operation of PPBR at lower dilution rates is recommended for continuous biological treatment of wastewaters for phenol removal.