JPS62128908A - Production of gouging carbon - Google Patents

Abstract

PURPOSE:To improve the adhesion of the surface of gouging carbon to copper plating by reheating a baked carbon rod in an oxidizing atmosphere so as to expose a rough surface. CONSTITUTION:A carbon rod baked in a nonoxidizing atmosphere is reheated to 500-900 deg.C in an oxidizing atmosphere such as the air. By the reheating, a dense film formed on the surface of the carbon rod during molding is removed and a rough inner surface is exposed. The exposed surface is plated with copper. Plating enters the surface pits and gouging carbon having superior adhesion to copper plating on the surface is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for producing gouging carbon.

Conventional technology Conventionally, cowling carbon is produced by directly applying steel plating to the surface of a carbon rod that has been fired in a non-oxidizing atmosphere, or by polishing the surface of the carbon rod with a grindstone. It is manufactured with a rough surface and copper plating applied to its surface.

Problems to be Solved by the Invention Gouging carbon is manufactured by plating the surface of the carbon rod with copper in order to be used with large currents, but if the adhesion between the surface of the carbon rod and the copper plating is poor, Because the current is concentrated, the amount of heat generated increases locally, causing the copper plating in that area to melt. If this phenomenon continues, the copper plating, which normally dissolves from the tip as the carbon is consumed, will dissolve when gouging begins, regardless of carbon consumption. As a result, the carbon rod is exposed for an abnormally long time, increasing the overall resistance and decreasing the current.
A problem arises in that gouging is no longer possible. Therefore, in order to roughen the surface of the carbon rod and improve its adhesion to the copper plating, a method of polishing the surface with a whetstone has been adopted. However, this method has the problem that a large force is applied to the carbon rod during polishing, causing the carbon rod to break.

Means for Solving the Problems As a method for solving the above problems, a method is taken in which the surface of the carbon rod is reheated to SOO''C to 900°C in an oxidizing atmosphere, for example, in air.

Effect: By using the above means, it is possible to remove the dense thin skin that forms on the surface layer during molding of the carbon rod. This exposes the rough internal surface and creates many holes on the surface.
If copper plating is applied, the plating will penetrate into the hole. When the plating enters this hole, a so-called anchor effect is produced, which has the effect of improving the adhesion with the plating.

However, the above-mentioned means have a relationship between the ripeness and time; for example, heating time in air at 900'C is about 1 to 2 minutes, and at 600C, heating time is 20 to 40 minutes. Temperatures exceeding 900"cl or temperatures below 6oO℃ may be used, but 9Qo"
If the temperature exceeds 600°C, it will take a longer time to absorb product variations, and if the temperature is less than 600°C, it will take a longer time. It is appropriate to set the temperature to about 500°C.

Furthermore, if the heating time is too long, the effect of oxidation is not limited to the surface layer, but also affects the inside, resulting in the diameter of the carbon rod becoming extremely thin and the apparent density decreasing.

Therefore, the heating time does not necessarily have to be uniformly long; an appropriate width can be determined depending on the temperature.

EXAMPLE Carbon rods with extremely dense surface layers were prepared and heated under various conditions. The results are shown in the table below. Heating is done using an electric furnace.

It was done in the air.

As shown in the above table, there is a relationship between temperature and time, and although it takes a long time at low temperatures, it was found that the method of the present invention is effective.

This judgment was made by making a carbon rod with an outer diameter of 8 mm, conducting it under the above conditions, discharging it with a current of 450 A after copper plating, and validating the carbon rod with an exposed part length of 20 mm or less. .

Effects of the Invention As shown in the above examples, the method of the present invention has the effect that the dense layer on the surface of the carbon rod is removed and there is no rough surface.

Claims (1)

[Claims] A method for producing gouging carbon, which comprises roughening the surface of a carbon rod by heating a carbon rod fired in a non-oxidizing atmosphere to 500 to 900°C in an oxidizing atmosphere.