Surface Copper Coating Method of Tungsten Carbide Copper Composite

Tungsten carbide-copper powder metallurgical composite is a pseudo-alloy composed of tungsten carbide with high melting point, high hardness, high conductivity and high thermal conductivity. Because of its excellent arc erosion resistance, welding resistance, high strength and high hardness, it is widely used as electrical contact materials, resistance welding, EDM and plasma electrode materials, electrothermal alloys and high density alloys. And the heat sink substrates of electronic devices such as computer central processing system, lead frame of large-scale integrated circuits and solid-state microwave tubes.

Although the theoretical density is 98%~99%, in actual production, there are many situations because of various reasons. Recently, based on the infiltration process, some scholars have proposed a surface copper cladding method, which can increase the infiltration density of tungsten carbide copper composites by more than 99% or even full density. The process is as follows:

(1)Mixed WC powder: the WC powder with an average particle size of 0.05 M, 0.2 m, 1 m, 3 m, 8 m is mixed evenly according to the weight percentage of 1:2:3:3:1. The mixed WC powder and copper are mixed with a certain amount of molding agent and spray dried for granulation.

(2)Tungsten carbide skeleton pressing: forming in the die, pressing pressure 150-400 MPa, obtain tungsten carbide skeleton blanks with various specific shapes;

(3)Punch the oxygen-free copper into the required weight copper bars as sintering flux;

(4)The skeleton compact and sintering infiltration agent are stacked together and sintered in a graphite mould matched with its outer circle. The sintering temperature is raised to 1250 ℃ in a vacuum furnace. The holding time is 1h. The tungsten-copper carbide alloy is sintered, and a copper layer of 0.3-5mm thickness is left on the surface of the alloy. The sintering and copper cladding are completed at one time.

Through infiltration sintering, the tungsten carbide copper alloy surface is adhered to a certain thickness of copper layer to improve the welding performance of tungsten carbide copper alloy. The whole preparation process is simple and controllable, and the cost is reduced. The relative density of the alloy as a whole can be more than 99% or even full compactness. Its performance is better, and it can be applied to more stringent conditions.

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