Erosion difference of growth and nucleation sides of free-standing diamond films prepared by DC arc plasma jet CVD

Solid particle erosion behaviors of the nucleation and growth surface of free-standing diamond films as a function of erosion time were studied by a laboratory designed blast type erosion apparatus. The surface roughness and the transmission loss were used to evaluate the extent of erosion performance. Results showed that the erosion damage features generated by impact appeared after erosion for 5 s and 30 s for nucleation and growth surface of diamond films respectively, and primarily occurred at grain boundaries in the form of micro-cracks. Then the local chipping of small sections on the border of cracks was followed resulting in material removal. The threshold erosion time, to maintain the transmission at 10.6 μm still above 60%, was 60 s and 300 s for nucleation and growth surface of diamond films. The growth surface of diamond films exhibited about 5 times higher erosion resistance for ending up with relatively lower surface roughness and transmission loss compared with the nucleation surface, which was in accordance with the ratio of grain sizes.