NEW COMPOSITE COMPOSED OF BORON-CARBIDE AND CARBON-FIBER WITH HIGH THERMAL-CONDUCTIVITY FOR FIRST WALL

A new composite was created from B4C powder and carbon fiber by hot-pr essing at 1700 degrees C or more. The composite sintered at 1700 degre es C with 20-35 vol% B4C shows a thermal conductivity of 250 W/m . K a t 25 degrees C which is slightly lower than the felt type C/C, but its value becomes higher than the C/C at temperatures above 400 degrees C . The composite with 40 at% B shows more controllable recycling proper ties than B4C, The erosion yield for the composite is about half the y ield for graphite at 800 K, After electron beam irradiation in order t o test heat resistance no cracks were detected up to 22-23 MW/m(2) lea ding to a surface temperature of 2500 degrees C.