Method of roughening surfaces

Abstract

Carbon commutator parts used as races for brushes in electric motors are typically soldered to copper carriers. The solder does not bond well unless a metallic coating is first placed on the carbon part. To improve adhesion between the metallic coating and the carbon part, the surface must first be roughened. An improved method of roughening the surface involves immersing the carbon part in an aqueous solution of sodium hydroxide or potassium hydroxide, connecting the carbon part as an anode, and applying an electric current for two or three minutes. This produces oxidation on the surface of the pressed body, thereby roughening its surface, so that the solderable metallic coating will subsequently adhere much better.

Dependencies are inferred from the claim text.