Fe-Ni films were electroplated in a citric-acid-based plating bath, focusing on the current efficiency of the plating process. We prepared the plating baths with various citric acid contents, and evaluated the magnetic properties of the films and the current efficiency. The film with Fe content of approximately 22 at. % was obtained by adjusting the iron sulfate content in the plating bath, and we found that the Fe-Ni films with low coercivity (<30 A/m) could be obtained in the baths with various citric acid contents. For the current efficiency, we found that the baths with low citric acid content are effective to obtain high efficiency. The bath with the citric acid content of 10 g/l showed high current efficiency (85%), and the high efficiency enables us to increase the plating rate. The maximum plating rate was 186 lm/h, and we obtained 1.3 times higher rate compared to that for our previous study. Therefore, we concluded that the bath with low citric acid content is a suitable plating bath to obtain thick Fe-Ni films in a short time. V C 2015 AIP Publishing LLC.
I. INTRODUCTIONFluxgate sensors are widely used in many facilities as a current sensor with high sensitivity, and a Co-based amorphous ribbon or an Fe-Ni-based alloy is commonly used as a core material for them . Although the sensors using these materials have high sensitivity, the temperature variation of the sensitivity is large due to their low Curie temperatures (200 -400 o C) [1][2][3] . Therefore, development of fluxgate current sensors with high robustness against the variation of temperature is required, and we focused on soft magnetic Fe-Ni-Co alloys with high Curie temperature . In this study, we fabricated a fluxgate current sensor with Fe-Ni-Co ring core, and evaluated the effect of temperature on the sensitivity . II. EXPERIMANTAL PROCEDURESSince the fluxgate current sensor needs to be driven at high frequency, we need to reduce the eddy current loss in the Fe-Ni-Co ring core . One of effective methods to reduce the eddy current loss is reduction in the thickness of the core . In order to fabricate the thin ring core, we used an electroplating method in this study . The electroplating conditions were decided based on our previous studies for the electroplated Fe-Ni films [4][5][6] . The Fe-Ni-Co films were plated on the Cu ring (ID: φ36 .7 mm, OD: φ44 .1 mm), and we obtained approx . 20 μm-thick Fe 15 Ni 46 Co 39 ring core . A fluxgate current sensor was fabricated using the ring core and a resin case . The turn number of excitation coil and detection coil were 100 and 300 turns, respectively . The excitation current in all cases was fixed a 1 kHz triangle wave, and the excitation current varied in the range between 220 mA and 430 mA . In order to compare the temperature characteristics of the sensitivity, we also fabricated a fluxgate current sensor with approx . 20 μm-thick Fe 21 Ni 79 ring core . The sensor was placed in a constant temperature bath, and the measurement temperature varied from -10 to +125 o C . We applied dc current from -3 A to +3 A to a conducting wire passed through the center of the sensor . We carried out a FFT signal processing for the sensor output, and detected the applied current values using the second harmonic voltage in the output . We obtained a plot data consisting of a total of 55 points, and calculated the sensor sensitivity by using the least squares approximation method . Figure 1(a) shows the sensor output as a function of the measurement current in two sensor comprising each Fe-Ni and Fe-Ni-Co ring core, respectively . As shown in Fig . 1(a), the sensitivity of a sensor with the Fe-Ni-Co core is superior to that for a sensor with the Fe-Ni one under the same excitation conditions . The measurement in the induced voltage waveform of the detection coil indicated that the saturation magnetic field of the Fe-Ni core is less than that for the Fe-Ni-Co core . T . Kilić et al. reported that the sensitivity of the fluxgate sensor depends on the relative permeability and the cross-sectional area of the core, the excitation frequency, the turn number of detection coil, an...
I . INTRODUCTIONRecently, size-reduction of magnetic devices is strongly required, and it is well-known that an increase in driving frequency is one of methods to reduce the size of the devices . For high frequency driving of the devices, we need to reduce eddy current loss in the cores . Since the eddy current loss is strongly affected by the thickness of the core, the reduction in the thickness is effective to reduce the eddy current loss . Although typical magnetic thin ribbons, such as amorphous or nano-crystallized ones, are prepared by the rapid quenching methods, very thin ribbons (< 10 mm) is not easy to obtain by the quenching methods . Therefore, we focused on electroplating methods since the thickness of the ribbon can be easily varied by the control of the plating time . In this study, we prepared Fe-Ni thin ribbons prepared by an electroplating method, and evaluated high frequency properties of a toroidal core made from the Fe-Ni thin ribbons . II . EXPERIMENTAL PROCEDDURES The electrolyte of the plating bath contained the following: 275 g/L of NiSO 4 ×6H 2 O, 25-140 g/L of FeSO 4 ×7H 2 O, 50 g/L of NaCl, 10 g/L of citric acid, and 5 g/L of C 7 H 4 NNaO 3 S×2H 2 O . A Ni square rod (5×5×350 mm) and a Cu sheet (0 .5×5×350 mm) were used as electrodes, and the 350 mm long Fe-Ni films were electroplated on the Cu sheet . The current density and the bath temperature were 200 mA/cm 2 and 50 °C, respectively . The plating time were varied from 2 to 5 .5 min in order to control the thickness of the ribbon . The above-mentioned bath composition and the plating conditions were based on our previous studies [1][2][3][4][5] . After the plating, we peeled off the 350 mm long film from the Cu sheet, and both ends of the long film were cut off approximately 50 mm . Consequently, we prepared approximately 250 mm long Fe-Ni thin ribbons for the evaluation of high frequency properties . III . RESULTS AND DISSCUSSION We prepared the Fe-Ni ribbons with various thickness and saturation polarization J s as shown in Fig .1 . The J s of the ribbons was varied by the changes in the composition of the film . The Fe content of the ribbons with J s = 1 and 1 .5 T were approximately 20 at .% and 40 at .%, respectively . The thin ribbons (< 10 mm) with low J s could be obtained easily, indicating that Ni-rich films could be easily peeled off from the Cu sheet . On the other hands, it was not easy to obtain the thin ribbons with high J s due to the difficulty of the peeling . Therefore, we prepared a toroidal core using the long ribbons with J s ≈ 1 T in this study . Figure 2 shows iron loss of the toroidal core as function of frequency . We also showed the result for a toroidal core made from an amorphous ribbon (2605HB1) produced by Hitachi Metals, Ltd . as a reference . As shown in Fig .2, the Fe-Ni core showed much lower loss compared with that of the amorphous one in high frequency region (> 50 kHz) . This result implies that the prepared Fe-Ni thin ribbon is an effective material for high frequency driving . From these resul...
TWO cases o f Pneumocystis carinii pneumonia occurring in adults with malignant lymphoma and acute lymphoblastic leukemia respectively are reported. Pneumocystis pneumonia i n adults i s a rare complication o f certain diseases, especially malignancies o f the lymphoreticular system, where host resistance i s lowered b y the underlying disease or by therapy. The disease i s frequently associated with cytomegaiic inclusion disease. I t i s important that pathologists and clinicians be aware o f this disease, since i t may b e expected that i t w i l l be observed more frequently as the use o f steroids and cytotoxic drugs increases. ACTA PATH. JAP.
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