Bing Han

Nanocrystallization behaviour and optimized magnetoimpedance effect in FeZrBNbCu alloys

The work aims at understanding the changes in magnetic properties and the magnetoimpedance (MI) effect for the Fe84.5Zr4B8.5Nb2Cu1 (FZBNC) nanocrystalline alloys with the annealing temperature (Ta) from the microstructure point of view. The as-quenched FZBNC ribbons were annealed in a vacuum condition at selected temperatures for 20?min. The microstructures of the specimens were examined by the x-ray diffraction technique. The bcc ?-Fe phase is identified from the XRD patterns. The mean grain size of the ?-Fe phase (D1) at different annealing temperatures (Ta) was estimated using Scherrers equation. The results show that D1 for the sample annealed at 575??C is about 20?nm, which is the smallest value among all the samples. Measurements on the MI effect reveal that the FZBNC ribbon annealed at 575??C exhibits the most drastic MI ratio of 756% at 600?kHz accompanied by the field sensitivity of 108%?Oe?1, while a large MI effect is not observed in the sample annealed at other temperatures. The origin of the excellent MI effect is investigated in this paper.

Influence of Fe on magnetoimpedance effect of Co72-xFexZr8B20 alloys

The magnetoimpedance (MI) of as-spun amorphous Co72−xFexZr8B20 (CFZB, x = 0, 2, 5, 7u2009at.%) alloys has been measured at a frequency ranging from 310 to 1110u2009kHz and a dc magnetic field between 0 to 70u2009Oe. The maximum MI ratio ΔZ/Z(%)max of the CFZB alloys increases with increasing frequency for each sample and decreases with the increment of Fe content at any frequency. The most drastic MI effect, the maximum value of about 90% at 1110u2009kHz accompanied by the field sensitivity of 18%u2009Oe−1, is observed in CFZB without Fe. Magnetic measurements reveal that coercivity of CFZB decreases first and then increases with increasing Fe content, and the minimum value of about 1.6u2009Oe is obtained in the sample with x = 2u2009at.%. The permeability of CFZB was evaluated from quasi-static hysteresis loops, indicating that the Fe-free CFZB is of the largest permeability. Measurements on electrical resistivity suggest that the Fe-free sample possesses smaller resistivity while the sample with x = 7u2009at.% has a much larger resistivity compared with CFZB with 2 and 5u2009at.% Fe. The correlation between MI effect and magnetic properties together with electrical resistivity for the CFZB alloy is discussed in this paper.

The Design of Borehole-Surface Networked Oil-Water Interface Resistivity Imager Receiver

The borehole-surface networked oil-water interface resistivity imager receiver which is in-depth research and designed in the thesis bases on the borehole-surface resestivity method.The text recommended a few hardware and the software constitution of module. The main function of every module is set forth in detail.These include the kind of system error and its calibration and principle calculation,the best way to weak low frequency signal conditioning,synchronization technique that the system applied.

Design of Time-Domain Airborne Electromagnetic Full Bridge Boost Switching Power Supply

According to the specific requirements of time domain airborne electromagnetic method detection system, a whole bridge high-power switching power supply is designed based on limited double pole control. Combined with the designed whole bridge topologies, its working process is discussed and the realization process of soft switch is analyzed. Through the specific experimental analysis, it can verify that the limited double pole control method can well realize zero voltage switch and zero current switch of the switch tubes, it can improve the work efficiency of the switching power supply. The power supply has been successfully applied to the scientific research project at present.

Magnetic hysteresis under compressive stress at high applied field

The magnetic properties of material are sensitive to applied stress. The aim of this paper is to designed and fabricated a hysteresis imaging apparatus for nondestructive evaluation of stress concentration in ferromagnetic material. It has been applied successfully to measure the hysteresis loops of Q235 steel under various fixed compressive stress. The remanence Br derived from the loops is more accurate and suitable to characterize the stress in a material.

Current sensor based on amorphous alloy ribbon

A novel noncontact current sensor based on Co-rich amorphous alloy ribbon is presented. Differing from the formerly reported sensors, a permanent magnet is used to supply bias magnetic field. The driving signal is provided by CMOS IC oscillator. The sensitivity of final sensor response reaches up to 461 mV/A, and the error of measurement repeatability is less than 0.1%.

Measurement of Hysteresis Loop by Using Pulsed Magnetic Field in LabView Environment

An apparatus for in situ measuring the hysteresis of magnetic materials by using pulsed magnetic field is structured. The samples were locally magnetized to saturation by the pulsed magnetic field. The pulsed field is generated by the discharge of a capacitor over the magnetizing coil. The measurement has been developed in LabView environment using National Instrument Data Acquisition Cards. The hysteresis loops of Q235 steel samples under various compressive stresses are presented.

Investigation on the Applicability of Single-Yoke Magnetic Testing under Applied Stress

A single-yoke magnetic probe was used to study the magnetomechanical effects under the applied stress. The stability and the reproducibility of the induced signal V were discussed. The presented measurement for magnetically open samples showed a good reproducibility via daubing magnetism Glue between the probe and the sample and establishing an offset magnetic field along applied stress direction.