Effect Of Current Variation Research Articles

Effect of Current Variation on Microstructure and Properties of B4C Nickel-base Alloy by Plasma Surfacing

In order to study the hardness of nickel-based alloys and the effect of different mass fraction boron Carbide on the microstructure of nickel-based alloys. In this paper, different amounts of boron carbide are added to the nickel alloy powder. A layer of nickel alloy surface layer is welded on the surface of the Q235 steel plate by plasma surfacing technology. The microstructure of the laminate is observed and analyzed by using Caisijinxiang tissue microscope. The hardness of the welding layer was tested by microhardness meter and the influence of boron Carbide on nickel alloy was obtained. The results show that boron carbide and nickel base alloy are well fused. The surfacing layer is mainly composed of fine dendrites and herbaceous eutectic structures. The addition of boron carbide can significantly improve the hardness andfine structure of the surfacing layer. With the increase of the content of boron carbide, the hardness of the surfacing layer first increases and then decreases. The experimental data show that when the mass fraction contentof boron carbide is 6% and the current is 110A, the hardness of the welding parts is higher.

MWCNT from Carbon Black: Effect of Current Variation and Arc Application Time

Carbon black can be used as a raw material to synthesize multi walled carbon nanotubes (MWCNTs). The present study focuses on synthesis of MWCNTs from carbon black using pulsed arc discharge method in Argon atmosphere. The morphological changes during conversion from carbon black to carbon nanotubes by varying arc current and arc application time is investigated. Scanning Electron Micrographs of the deposited carbon nanostructures suggest that MWCNTs are formed at 40A and for a minimal exposure time of 60sec.As we kept increasing arc current the granular structure of Carbon black transform to flakes structure and then to rigid rod like structure before getting finally converted to MWCNT.

Coating of AISI 1010 Steel by Ni–WC Using Plasma Transferred Arc Process

In the present study, mixed powders of 95% Ni and 5% WC were coated on the surface of AISI 1010 steel by plasma transferred arc process. The effect of current variation on the microstructure and hardness of the alloyed surfaces was investigated. After deposition, microstructural analyses including metallographic examination and microhardness measurements of the coatings were performed. The alloyed surfaces showed an increase in hardness when current was increased and this was attributed to the formation of hard phases. Upon solidification of the coating, different microstructures formed depending on the processing parameters. The microstructures of the alloyed surfaces consisted of widmanstatten ferrite, grain boundary ferrite, acicular ferrite, bainite and martensite.

A Disturbance Rejection Strategy for Asynchronous Motor of the Electric Vehicle in Speed-Open-Loop Operating Mode

For any electric vehicle on the road, it is inevitable to be influenced by parameter uncertainties and some kinds of disturbance torques, which present challenge for the controller design in the electric vehicle. Therefore, control of the electric vehicle to achieve the safety running requirement becomes important. In this paper, we investigate the control method for electric drive system of the electric vehicle from both theoretical and applied perspectives, then, speed loop inverse based disturbance rejection control strategy is proposed. The proposed approach is illustrated by implementing it into an experimental platform. The experimental results demonstrated that the proposed control method can achieve rapid response to current variation at operating frequency of electric vehicle, and substantially suppress the adverse effect of current variation at high frequency.

Effect of current variation on the dynamics of railgun plasma armatures

The effect of current variations on the behavior of railgun plasma armatures is investigated with a one‐dimensional, time‐dependent model. Three typical current profiles are considered: two inductive profiles, one with a time constant of 0.5 msec and the other with a time constant of 2.0 msec, and a capacitive profile. All three calculations are for an armature in a 5 cm square‐bore railgun. It is observed that current variations create oscillations in the armature length, projectile acceleration, and projectile jerk. In addition, the current profile significantly affects the axial distribution of the plasma velocity, current density, and total pressure. The significance of these transients on the design of projectiles and the interpretation of diagnostic data is discussed, and suggestions for future calculations are outlined.