Guangming Zheng

Ultrasonic Electrodeposition of Cu–SiC Electrodes for EDM

Cu-SiC composite electrodes composed of both a Cu matrix and dispersed inert SiC particles were fabricated for electrical discharge machining (EDM) using the ultrasonic-aided electrodeposition technique. The influence of ultrasonic power on the surface morphology, content of SiC particles, and EDM wear rate of the fabricated Cu-SiC composite electrode were investigated. Results show that the incorporation of SiC particles into the composite electrode was enhanced and that the uniformity of particle distribution in the Cu matrix improved when the ultrasonic dispersion was initiated during electrodeposition. The composite that was generated at low ultrasonic power contained more SiC than that produced at high ultrasonic power. Moreover, the Cu-SiC electrode fabricated at low ultrasonic power displayed the least erosion wear during EDM.

Electroforming of TiB2-Reinforced Copper Matrix Electrode for EDM

TiB2 particle-reinforced copper matrix composite is electroformed in copper sulfate on stainless steel plate. The impact of the particle content in electroforming solution on the surface morphology, hardness, and electrical conductivity of the electroformed composite are studied, and the influence of electroforming current density on the effective content of particles in the composite is also analyzed. The results show that when the content of particles in electroforming solution is 25 g/L, the current density is 4 A/dm2, particles in the electroformed composite are well-distributed, and the average grain diameter can be reduced to 20 µm. The microhardness of Cu/TiB2 composite reinforced by particles with diameter of 3 µm is 25% higher than that of electroformed copper, and its conductivity remains 86% of the copper.

Experimental Investigation on Sialon Ceramic Inserts for Ultra-high-speed Milling of Inconel 718

A series of milling aerospace material Inconel 718 experiments were conducted with a sialon ceramic tool to investigate chip evolution, cutting force, and tool wear at different cutting speeds. Round inserts were used at ultra-high-speeds under dry cutting conditions. A scanning electron microscopy and an optical microscope were used to observe the worn surfaces and to reveal the wear mechanisms of the inserts. The experiment results showed that the macroscopic shape of the chips was small scraps and fan-shaped. With the increase in the cutting speed, the plastic deformation of the chips was increasingly serious. The minimal average cutting forces were obtained at vc = 700 m/min. The rise of cutting temperature was resulted from the increase in cutting deformation work and friction work with cutting speed. The combined effect of thermal stress and mechanical stress contributed to the tool chipping, flaking, microcrack propagation, abrasion, and adhesion which were the primary reasons of the sialon ceramic tool wear.