Electrodeposition tests results

The results of electrodeposition tests are shown in Table I, in which the acidic or basic characteristics of dispersants are related to the location of the centrum of particle potentials. 

Electrodeposition is the preferred method for preparing a thin, smooth, uniform, and stable source for counting, as discussed in Section 3.7. Empirically developed procedures are applied to the heavy elements in aqueous solution because they cannot be reduced to the metal the source is deposited at the cathode in what is believed to be hydroxy forms after partial reduction. Deposition is in acid solution, under various conditions that yield near-quantitative recovery from the solution. Test results specify the volume, reagent content, applied volts and amperes, and optimum time period (see Section 6.4.1). The cathode can be a platinum disk, but a polished stainless steel disk is satisfactory. 

Adhesion of copper films to PMDA/ODA polyimide was determined by peel tests conducted on samples that were prepared by vapor-depositing a thin layer of copper onto the polyimide and then building the thickness of the metal layer to about 18 p,m by electrodeposition of copper. Results of the adhesion measurements correlated well with substrate pretreatment. When the substrate... 

Resistance to corrosion Most authors who compare resistance to corrosion of electroless nickel with that of electrodeposited nickel conclude that the electroless deposit is the superior material when assessed by salt spray testing, seaside exposure or subjection to nitric acid. Also, resistance to corrosion of electroless nickel is said to increase with increasing phosphorus level. However, unpublished results from International Nickel s Birmingham research laboratory showed that electroless nickel-phosphorus and electrolytic nickel deposits were not significantly different on roof exposure or when compared by polarisation data. 

Electrodeposition experiments were carried out in the apparatus described earlier (4). The equipment is illustrated schematically in Figure 2. The circuit also included a strip chart recorder and integrator. A variety of metals were coated at the cathode using the standard condition of 200 V for 2 min. The cathode area was held constant at 7.3 cm, unless otherwise specified. After deposition, the metal test pieces were rinsed with deionized water, dried and weighed to determine the amount of polymer deposited. The number of coulombs was measured simultaneously in order to calculate current efficiencies. Results were analyzed and compiled in a simple computer program. A typical printout is shown below for a system with poor current cutoff (Table V ), and good cutoff (Table VI). The set of metals used as substrate are listed below. 

The effect of ultrasound on the process of tellurium anodic dissolution in alkaline solutions was studied by the method of plotting polarization and galvanostatic curves [148]. Tests were made in NaOH solutions (concentrations of 0—20 g/L), subjected to the action of ultrasound at a frequency 17.5 kHz and using Te electrodeposited under ultrasound. The anodic polarization curves plotted without ultrasound and in its presence shifted with increased NaOH concentration towards negative values as a result of the increasing rate of Te anodic dissolution. The presence of ultrasound inhibited the process of Te anodic dissolution, probably due to the desorption of OFT anions from the anode surface. This sonoelectrodeposited Te thus showed greater corrosion resistance in alkaline solution than that deposited... 

Ductile and easily buffed chromium deposits having satisfactory corrosion resistance have been produced thus 0.005 mm-thick chromium deposits applied to steel by chemical deposition or by electrodeposition gave similar results when subjected to a salt-spray test... 

Figure 14.2. Undermining of nickel electrodeposit on steel by galvanic corrosion in 3% NaCi solution (lOOx). Crack resulted from cyclic stressing in a corrosion-fatigue test [H. Spahn and K. Fassler, Werkst Korros. 17, 321 (1966)].

Another simple approach to glucose detection was recently proposed by Tsai and co-workers, who employed atomic force microscopy (AFM) lithography to score nanochannels in a poly(methyl methacrylate)(PMMA) film coated onto a platinum substrate.Subsequent electrodeposition of the GOx enzyme into the nanochannels resulted in the growth of horizontal GOx nanorods, with heights as small as 80 nm. The analytical figures of merit for this approach, which was tested for 25x8 pm long chaimels, did not compete with the above examples, but the sensor is yet to be optimised and the simplicity of the approach makes it accessible to any research laboratory. 

The model expressed by Eq, 11 is used to project the time-to-failure from test to field conditions, making use of the failure acceleration due to relative humidity, temperature, and electric field. The model has been verified experimentally and has been consistent. The values of B, m, and A HpWillvarywith contaminants, material and surface condition. The ionic impurity environment is assumed notto vary among all samples under test within the same experiment. The metallic ion concentration will vary with the samples contamination due to process residues and other ionic species that may be present in the system. Adding chemicals to enhance the oxidation/reduction process, therefore the electrodeposition, is another way to accelerate the formation of dendrites, however, itwould be difficult to relate the results to field conditions if a new mechanism is introduced. 

The in situ stress transition of the electrodeposited Sn and Sn62Ni3s anodes were evaluated by means described above. Figure 3.22a,b shows the results of in situ stress measurements of the Sn and the Sn62Ni38 electrodes, respective. The negative values of the deflection profile represent compressive stress (expansion of the active material). Tests of repeated charge-discharge cycles showed that the deflection response of the electrode continued, and it was confirmed that the substrate elasticity was retained during the first cycle. It is difficult to obtain quantitative reproducibility due to the individual textures that differ with each electrode (such as their cracks and pores). However, the qualitative reproducibility which indicates that the electrode shows a tendency that is dependent on the electrode composition has been confirmed. 

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