Properties of WC-Co Ceramic Coatings of Ultra-Fine Grains Prepared by Electro-Thermal Explosion Method

Abstract

The high velocity spraying experiments for preparing WC-Co ceramic coatings were carried out by using an electro-thermal explosion directional spraying device. The transient parameters of both the discharge circuit and the voltage applied to the WC-Co sheet were measured. Velocity of the shock wave in the explosive spraying nozzle was approximately measured and that was described with a one-directional piston model. The velocity of molten particles of WC-Co ceramics was estimated to be about 3162m/s. The microstructures and micro-hardness of the WC-Co coating, the interface between the coating and substrate were analyzed in details. The visible WC grain diameter of the coating ranges from 70 to 350nm, and the average value is 195nm. A metallurgical bonding layer with a thickness of about 1 was found at the interface. The values of micro-hardness of the coating are 1-1.4 times of the original one, and the micro-hardness near the interface is much higher than that of the substrate

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“…Electro-thermal explosion spray coating system is composed of high voltage DC power supply, energy accumulating capacitor set, triple-pole switch and electric explosion chamber [4] . Fig.…”