Sand erosion of freestanding diamond films prepared by DC arcjet

Sand erosion behavior of freestanding diamond films prepared by high power dc arcjet operating at gas recycling mode was investigated by a laboratory designed blast type apparatus. Four different erodent: glass bids, SiO2, Al2O3, and SiC were used. The speed of the erodent particles was measured by the double disk method. It was found that the erosion behavior for the as-grown and the polished diamond films was quite different. At the initial stage, the erosion rate was rather high for the as-grown diamond film, which rapidly decreased with the increase in erosion time, and eventually reached the steady state erosion stage on prolonged erosion. Whilst for the polished diamond film, the erosion rate was quite low at the initial stage, which rapidly increased with the increase in erosion time, and finally reached the steady state erosion stage after a long erosion time. Surface damage was investigated by SEM observations and Raman spectroscopy. Possible mechanism responsible for the difference in erosion behavior was briefly explained. Comparison of the erosion behavior of freestanding diamond films was also made with the other commonly used IR window materials (Ge, MgF2, MgAl2O4, ZnS and quartz glass). Detailed results were discussed.