Bv. Tanikella et al., INDENTATION AND MICROCUTTING FRACTURE DAMAGE IN A SILICON-CARBIDE COATING ON AN INCOLOY SUBSTRATE, Surface & coatings technology, 88(1-3), 1997, pp. 119-126
The fracture damage morphology for static indentation tests and contro
lled microcutting tests using a Vickers indentor was investigated for
an amorphous silicon carbide coating deposited on an Incoloy substrate
. Crack initiation thresholds were detected for both testing modes usi
ng an acoustic emission sensor. The fracture damage morphology for sta
tic indentation consisted of Hertzian-like cracks surrounding the inde
ntation site with no lateral crack-chipping occurring up to the maximu
m indentation load of 8 N. In contrast, microcutting generates lateral
cracks at the microcutting groove entrance for loads as low as 0.3 N.
For loads up to 1 N, the groove damage was confined to the 5 mu m thi
ck coating and the fracture response is similar to that occurring in a
monolithic brittle solid. At higher loads, extensive lateral crack ch
ipping occurred along the microcutting grooves accompanied by coating
decohesion at the root of the chip.