THERMAL-SHOCK EXPERIMENTS FOR CARBON MATERIALS BY ELECTRON-BEAMS

Thermal shock tests by electron beams were conducted on various commercial carbon materials including isotropic graphite, pyrolytic carbon coated graphite, carbon fiber composites and on synthesized carbon/boron materials. Thermal stress cracking and surface erosion were compared among the materials, and relations between resistance to high heat flux damage and physical properties were investigated. The synthesized carbon/boron material exhibited higher resistance to thermal stress fracture than most isotropic graphites. A carbon fiber composite (CX-2002U) with high thermal conductivity exhibited higher resistance to surface erosion than isotropic graphite (IG-110U). Resistance to surface erosion increased with increasing sample thickness and decreasing pore size. In pyrolytic carbon coated graphite the incubation period for erosion decreased with increasing coating thickness. The eroded surface of the carbon/boron material was smoother than that of graphite, which showed that erosion by particle emission was suppressed in the carbon/boron material.