Erosion behaviour of boron carbide under high-power pulsed fluxes of hydrogen plasma

The erosion values of hot-pressed in vacuum boron carbide were measured under conditions of irradiation by 1 μs pulses of hydrogen plasma with an energy flux density on the target of about 5.5 J cm−2. At variations of angles of plasma flux incidence from 0 to 85° the net erosion values changed from 6×10−5 to 4×10−4 g cm−2 pulse. For B4C balls the erosion values were identical to those for flat targets at angular incidence or 45°. No dependence of the erosion values on the density (1.99–2.46 g cm−3) and the number of pulses (2–50) was observed. As optical examination of surface morphology or irradiated samples has shown a new kind of erosion mechanism takes place during irradiation, where erosion processes are determined not only by the interaction between the plasma and the bare B4C-surface but also by plasma interaction with the scale (shelling layer) and flakes which have coated the target surface after a few first plasma pulses. Possible physical mechanisms of this erosion behaviour and their implications for the solid target boronization procedure in plasma devices and for other technological applications of boron carbide are also discussed here.