Papers by Keyword: Depolarization

Abstract: This paper represents the experimental studies on the throwing power of sacrificial anode cathodic protection system applied to reinforced concrete piles in salt water condition by means of zinc anodes. Many previous studies show the effectiveness of sacrificial anode cathodic protection system, however, the major problem of sacrificial anode cathodic protection system is limited a distance to the point reaching protection current from the anode in high resistivity environments such as concrete, etc. In case of concrete pile in sea water condition, it should be combined submerged zone, tidal zone, splash zone, and atmospheric zone. In this study, the cathodic protection current by zinc sacrificial anodes was limited to scores of centimeters above the water line with tidal, depending on the concrete resistivity. Experimental tests were carried out on pile type reinforced concrete specimens with the change of water level. The test factors were corrosion and protection potential, current, and 4 hour depolarization potential. As a result of tests, cathodic protection current by zinc sacrificial anode was influenced up to about 10cm above the water line, and high resistivity areas such as atmospheric zone could not be protected with this system.

Abstract: To further shorten the charging time, enhancing charging efficiency and extending battery charge cycle life, this paper presents a variable frequency pulse fast charging methods based on fuzzy control depolarization. This method uses perturbation and observation method tracking resonant frequency real-timely and then finds the maximum current corresponding to the resonant frequency to charge the battery while using fuzzy control technology to detect and eliminate polarization effects arising from the charge process to accelerate the charging speed and realize frequency-varied fast charging. Experiments showed that using the fuzzy control frequency-varied pulse charging technique improves the charging time, charging efficiency, and rising temperature of the Li-ion battery by about 6.9%, 2.4%, 17.3%, respectively, as compared with the currently used fast charging method of intermittent alternating current.

Abstract: This paper presents the results of the effects of anodes for impressed current cathodic protection (ICCP) system on reinforced concrete. Experimental tests were carried out on reinforced concrete specimens with 3 different kinds of commercial anodes that are used for ICCP in order for comparative study. Results have shown that the type of anodes is irrelevant to the effectiveness of cathodic protection. CP current similarly flowed to the anodes regardless of anode types in seawater condition. In addition, current was much higher in seawater condition than freshwater and air condition. The results show that titanium rod anode was slightly more effective in fresh water, and titanium mesh anode showed a better performance in atmospheric condition. The potential drop caused by concrete resistance in atmospheric condition should be considered at depolarization potential measurement.

Abstract: Experimental results show that the samples gained in bath added Rare earth nitrate (REN), relative to the sample got in bath without REN, improve the anti-corrosion power of the coating because of increasing of covering rate of formless crystal Zn2Fe(PO4)2·4H2O (marked P) crystals and the ratio of P/(P+H) (H is the mark of Zn3(PO4)2 crystal) in the coating, combination of which with components parsing by EDS indicates that the sequence of contribution elements P and Zn to erosion resistance of coatings is P>Zn. And the correlative mechanism was discussed, which has it clear that RE is materially a catalyst holding excellent ability of carrying oxygen and cathode depolarization, its concentration gets so constant in certain range that it is much steadier and more efficient than the usual consumptive oxidants like nitrates. In a word, REN plays the role of surface regulator, accelerant and densification agent, which speeds up the phosphating, and bids it effective to enhance the anti-corrosion power of the coating. The addition of REN, not only promote the phosphating film formation and substantial reduction or exemption of nitrite. So, REN is green phosphating accelerator of live up to one's name.

Abstract: This article reviews the theories and experiments on the macroscopic/nanoscopic scales, which indicate that nearly free electrons/holes appear at polarization discontinuities as a result of not only extrinsic mechanisms such as imperfections but also intrinsic mechanisms. We examine the consistency of these theories and experiments with conventional ones. Such electrons/holes lead to various novel properties of ferroelectrics and provide new insight into ferroelectricity, including fundamental issues such as the origin of ferroelectricity. This origin appears naturally compatible with the existence of multiferroicity.

Abstract: The pivotal role of lithium batteries in energy storage is a well known fact. But in today’s fast paced revolutionary world, problems like charge retaining difficulty, excess heat generation, leakage etc make them impossible devices for energy storage. Instead of going in for the conventional lithium batteries, a new battery can be brought into existence which uses the body fluid (blood) as its electrolyte. Inside the mystic human system, during the oxidation process of the carbohydrates we consume, electrons are liberated which may be used to power up a tiny battery inside, the rate of which is controlled by the nanobots. As multifunctionality is the need of the hour, numerous tiny sensors placed inside our body which operate on MEMS technique not only monitors the body tissues but also detects any block in arteries and veins, cancer causing cells and gives suitable command to the nanobots. The rate at which the nanobots clear the imperfection can be made faster by swarm intelligence. The multifunctionality aspect of nanobots is further enhanced as they act as an effective substitute for dialyser and pacemaker.

Abstract: Na_0.5K_0.5NbO₃ (NKN) lead-free piezoelectric ceramics was synthesized by a mixed oxide reaction method. The ceramics was poled under an electric field of 3 kV/mm at 150 °C for 0.5 h. The thermally stimulated depolarization current (TSDC) measurement was carried out at the heating rate of 1 °C/min from room temperature up to 500 °C under an applied voltage of 0 and 0.5 V. The zero-bias TSDC pattern showed broad patterns around at 365 and 375 °C. These temperatures corresponded to the temperatures showing bending points in the Arrhenius plot of TSDC measured under 0.5 V. The oxygen vacancy related electrical conduction was changed at 313 °C at the heating step. The mobile oxygen vacancy in NKN ceramics was piled up under the poling field, and the oxygen vacancy was diffused at temperature higher than 313 °C.

Abstract: Lead-free Na0.5K0.5NbO3 (NKN) piezoelectric ceramics was synthesized by an ordinal solid state reaction method. The ceramics was electrically poled under 3 kV/mm at 150 oC for 30 min. The discharge current-flow was measured for the poled ceramics at the heating rate of 1 oC/min from room temperature up to 500 oC. The two sharp peaks were observed at 209 and 417 oC. These temperatures were corresponded to orthorhombic-tetragonal (TO-T) and tetragonal-cubic (TC) phase transition temperatures, respectively. The sharp peaks were mainly originated from the decrease of the spontaneous polarization. Additionally, the several large broad patterns were also observed at 280, 363 and 375 oC, According to the electromechanical coupling factor kp, which is the indicative parameter of the polarization, mainly decreased at TO-T and TC. These broad peaks were not associated with the spontaneous polarization. The peaks seem to have been originated from the discharge current of the oxygen ion migration on elevating temperature inside the poled NKN ceramics.