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Abstract:The dry electrical discharge dressing and truing technology was proposed to realize the high efficient and precise truing of diamond grinding wheel in this paper. Firstly, the V-shape tip of diamond grinding wheel was formed using dry electro-contact discharge (ECD) truing along setting crossed V-shape interpolation path. Secondly, the influence of different pulse discharge parameters on V-tip angle and V-tip radius was investigated, respectively. Finally, the trued V-tip diamond wheel was employed to fabricate micro-groove and micro-pyramid array structures on the surfaces of two hard and brittle materials by micro-grinding machining. The results indicated that the optimal pulse discharge parameters were open-circuit voltage E of 5V, pulse frequency f of 4000Hz and duty cycle d c of 50%. The least V-tip angle error and radius of trued SD600 V-tip diamond grinding wheel was 1.1º and 33 µm, respectively. The micro-groove and micro-pyramid structures with regular shape and smooth surface can was effectively machined on the surfaces of difficult-to-cut materials.

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It is challenging to efficiently prepare bimetallic composites with excellent metallurgical bonding. Here, we present a strategy, the ultrasonic insert casting (UIC) process, to solve this problem. The ultrasound cavitation effectively destroys the oxide film and promotes diffusion in the UIC-prepared steel/aluminum bimetallic castings, resulting in a uniform reaction layer between steel and aluminum. The reaction layer contains FeAl3, Al8Fe2Si, and Al4.5FeSi, and has a higher microhardness than the steel/aluminum matrix, with an average thickness of 8 μm. Moreover, the thickness of the reaction layer increases with the improvement of pouring temperature but the thicker reaction layer (approximately 12 μm) does not bring higher strength. The highest shear strength, about 70 MPa, is approximately three times higher than that without ultrasonic treatment. These results indicate a useful strategy for the low cost and high-efficiency preparation of metallurgical boding bimetallic casting.

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