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A coaxially integrated macro-micro composite actuator (MMCA) with large stroke and high accuracy is proposed by combining a voice coil motor (VCM) with the giant magnetostrictive actuator (GMA). The magnetic circuit model of the macro-motion part is established based on the driving principle of VCM, and the multi-field coupling model of the micro-motion part is established based on the Jiles-Atherton model. The finite element method was used to analyze the relationship between displacement, output force, velocity, acceleration, and time of the macro-motion part under different currents, the magnetic flux density, output force, and displacement curves of the micro-motion part, and the mutual influence between the macro and micro motion parts were analyzed. The prototype of the MMCA was developed, and an experimental test platform was built. The results show that the MMCA macro-motion displacement curve can fit the simulation curve well during open-loop positioning, and when the current size of the input macro-motion coil is 4 A, the experimental curve of the MMCA is the most consistent with the simulation curve. When closed-loop control, the motion curve of the drive can well follow the set displacement curve, in which the maximum stroke of the prototype developed is 50 mm, the positioning error of the macro-motion part is less than 20 μm, the maximum stroke of the micro-motion part is 40 μm, and the overall positioning accuracy of the MMCA is 0.14 μm. The research results provide a new idea and theoretical basis for further optimization and development of precision positioning platform with high precision and large stroke. [ABSTRACT FROM AUTHOR]

Introducing reinforcements is a crucial way to modify WCu electric contacts. Herein, the arc erosion performances of WCu/Ti3SiC2 under various direct current voltages are investigated. The eroded microstructures are observed by a 3D laser scanning confocal microscopy and a thermal field emission scanning electron microscope. Compositions of the eroded surfaces are analyzed by a Raman spectroscopy. With the elevated voltages, values of breakdown current, arc duration, arc energy, and arc discharge distance increase, while the breakdown strength decreases. Meanwhile, the eroded regions gradually change from circular shape to irregularly curved corrugations under the elevated voltages. Copper and Ti3SiC2 can disperse arc during arc discharge, and the liquid and gas generated by the two phases can make differences in protecting WCu/Ti3SiC2. [ABSTRACT FROM AUTHOR]

SF6/N2 mixture gas is an environmentally friendly sealing gas for power equipment. The multiple arc erosion performance of Ag/Ti3SiC2 composite was investigated in SF6/N2. During the multiple arc erosion process, the relative breakdown strength increased with the operation number, and the breakdown current and arc duration were randomly distributed in a certain range. Ag spheres were observed on the material surface in the arc erosion region. For the Ti3SiC2 reinforcing phase, a silicon de-intercalation phenomenon was observed in the eroded region. Additionally, instantaneous photographs of the arc erosion process were recorded. [ABSTRACT FROM AUTHOR]