| 摘要 |
<p>PURPOSE:To obtain the title base material with little light loss by feeding a specified mixed gas (vapor phase heat treating agent) into the gap between a core material and a clad mateiral prior to fusion bonding of the materials in production of the base material by a rod-in-tube method. CONSTITUTION:A core material surface-smoothened and cleaned by mechanical or chemical polishing or heat treatment is put into a clad material similarly treated, and they are heated to about 500-1600 deg.C with a resistance furnace, an oxyhydrogen flame or the like. At a state where the desired temp. is attained and fusion bonding does not occur yet, a hydrogen-free mixt. (vapor phase heat treating agent) consisting of one of C, N, O, S and Se, and one of halogen cpds. such as CCl4 is fed into the gap between the materials at a vapor phase state, and fusion bonding is finished at this state.</p> |
