Because tungsten has a high melting point and strong arc resistance, copper has excellent electrical and thermal conductivity, so copper-tungsten contact materials have good arc corrosion resistance and electrical and thermal conductivity and are widely used in SF6 high-voltage circuit breakers. In this article, let’s take a closer look at the copper tungsten contact material preparation method.
The specific steps of a new preparation method of copper tungsten contact material include：
Step 1. Take tungsten powder, high-purity nickel balls, and water and place them in a ball mill for ball milling.
Step 2. The obtained tungsten powder after ball milling is dried, annealed, shaped, pre-sintered, and copper sheet infiltration treatment is performed to obtain a copper-tungsten contact material.
Wherein, the weight ratio of the high-purity nickel balls to the tungsten powder is 4～10:1；the dosage of water is 120 ~ 150ml water for each 1kg tungsten powder; the ball milling time is 12～48h.
The reasons why put tungsten powder, high-purity nickel balls, and water in a ball mill according to a specific ratio for ball milling for a specific time:
On the one hand, during the ball milling process, the nickel lost from the high-purity nickel balls due to ball milling can be directly added to the tungsten powder as an additive, so that ball milling and adding additives can be performed simultaneously. Moreover, when the milling time is limited to the above range, the nickel in the contact material obtained accounts for exactly 0.1-1.0% of the total weight of the tungsten powder.
On the other hand, because the hardness of tungsten particles is much higher than that of high purity nickel spheres, the tungsten powder and the nickel spheres are fully contacted and grounded, and the nickel lost by ball grinding from high purity nickel spheres can be uniformly coated on the surface of tungsten particles, thus achieving the purpose of effectively improving the sintering effect of tungsten skeletons.
Note for this preparation method:
1. In order to reduce the introduction of impurities, the purity of the nickel ball should be greater than or equal to 99.9%, and the diameter should be φ6～φ30mm.
2. The copper sheet should be placed in the infiltration step, and the amount and ratio of the tungsten powder and the copper sheet can be calculated according to the copper-tungsten contact material to be prepared.
The advantages of the preparation method of the copper tungsten contact material are as follows:
Nickel powder can be added automatically while ball milling and the nickel powder can be evenly distributed in the tungsten powder, so that the obtained copper-tungsten contact has a uniform metallographic structure, and has excellent arc erosion resistance and high-temperature mechanical strength.
Thank you for reading our article and we hope it can help you to have a better understanding of the copper tungsten contact material preparation method. If you want to learn more about copper tungsten alloys or other refractory metals and alloys, we would like to advise you to visit Advanced Refractory Metals (ARM) for more information.
Headquartered in Lake Forest, California, USA, Advanced Refractory Metals (ARM) is a leading manufacturer & supplier of refractory metals & alloys across the world. It provides customers with high-quality refractory metals & alloys such as molybdenum, niobium, tantalum, rhenium, tungsten, titanium, and zirconium at a very competitive price.
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