Abstract: Provided is a carbon layer derived from carbide ceramics, wherein metal or non-metal atoms are extracted selectively from the surface of carbide ceramics to form voids, which, in turn, are filled with carbon synthesized by a carbon compound, thereby providing improved roughness and hardness, as well as to a method for preparing the same.

Abstract: Provided is a cooling ring for welding used to manufacture a bellows including a plurality of pairs of barriers, each pair formed of a first barrier and a second barrier disposed to face the first barrier. The cooling ring includes a body formed as a circular arc shape, disposed to attach the first barrier and the second barrier closely to each other while being in contact with at least one of the first barrier and the second barrier, the body including copper and a plating layer plating the body. The plating layer includes at least one selected from the group consisting of nickel and chrome. Since the cooling ring includes the body having the circular arc shape including copper and the plating layer plating the body, it is possible to prevent powder of a metal having high electrical conductivity, such as copper, aluminum, gold, and silver, during a welding process.