Evaluation of brazing joint of graphites and molybdenum

Bonding test of six kinds of graphites to molybdenum was performed in the following conditions: Brazing elements was obtained by mixing of titanium nickel and copper in the range of 90∼51w%, 40∼10w%, 31∼0w%, respectively. Nonpressed brazing was performed at maximum temperature 1,000℃ in a vacuum. Strength tests of these brazed joints were done in the conditions of at high temperature up to, 1,100℃ in a vacuum, after 200 heat cycles from room temperature to about 900℃. Optical observation were performed before and after electron beam tests at 3.0 kW/cm²·0.1 s·5 shots. The following results were derived: (1) The good mixing condition was found for titanium, nickel and copper brazing material at 64, 23 and 13w%, respectively. (2) Bending strengths of the brazed joints at room temperature were found to be proportional to the bending strengths of the graphite. (3) Bending strengths of the brazed joints shows no change until tested temperature reached 900℃ in a vacuum. (4) Bending strength of the brazed joints showed no change after 200 heat cycles in the temperature range of room ∼ about 900℃ and the electron beam tests. (author)