Search

We report herein on the arc erosion behavior of Ti 3 AlC 2 cathode under atmosphere at 7 kV d.c. voltage. The arc life and the breakdown strength for Ti 3 AlC 2 are 28.468 ms and 1.239 × 10 6 V/m, respectively. The process of arc discharging can be divided into three stages: arc formation, steady burning and attenuation, which was observed by a high-speed camera. During steady burning, the arc column is the brightest and the largest. The eroded material was detected by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscope and energy dispersive X-ray spectroscopy. Under the action of arc discharging, the arc erosion morphology characterized with cracks, pores, protrusions with holes displays on the surface of Ti 3 AlC 2 . Meanwhile, the material is dissociated and oxidized to TiO, TiO 2 , Al 2 O 3 , arising from the high temperature and energy intensity of electric arc. The different composition and Marangoni effect are responsible for the multiple morphologies. [ABSTRACT FROM AUTHOR]

The arc erosion behavior of Ag-Ti 3 SiC 2 material under various load voltages is reported here. At the load voltages of 3, 4, and 5 kV, the eroded area is circular. In contrast, the eroded area exhibits a dendritic morphology from 6 kV to 10 kV, which is due to the arc movement. Due to the thermal characteristics of the electric arc, Ag-Ti 3 SiC 2 melts, spatters, resolidifies, decomposes and oxidizes. Cross-sectional images of the eroded morphology show that Ag, Ti, and Si elements distribute uniformly on the surface without concentration. Due to the satisfactory wettability of the molten material, which is due to the formed oxides TiO 2 and SiO 2 , minor particle spattering occurred on the eroded surface. The breakdown strength is enhanced by the disappearance and reappearance of protrusions after 100 arc erosions; this outcome complies with a linear law. • Erosion behavior of Ag-Ti 3 SiC 2 cathode at different voltages is first studied. • Arc movement forms the dendritic morphology with higher energy at 6 kV–10 kV. • No elements concentrate on the cross-sectional image. • TiO 2 and SiO 2 improve the wettability of molten material, suppress spattering. • Breakdown strength is enhanced after 100 times of arc erosion. [ABSTRACT FROM AUTHOR]

Solid solution hardening is one of common methods to increase hardness of metals by adding solute atoms. The mechanism for solution hardening is ascribed to the differences in atomic size and elastic modulus between the host and the solute. However, the theory is somehow ambiguous without clear clues for optimizing the balance between the two effects towards maximized hardening effectiveness. Current selection of alloying elements for solution hardening is largely based on experience. In this study, we re-examine the conventional mechanism and propose a single-parameter model using electron work function (EWF) as an indicator to evaluate the capability of solute atoms in solid solution hardening. With relevant experiments, we demonstrate the correlation between electron work function and solution hardening effectiveness. The prediction from the proposed EWF model is consistent with the experimental observations. [ABSTRACT FROM AUTHOR]