Thermal characteristics of a Zr(B,C,N) coated layer manufactured by the PACVD process

In this study, thermal characteristics of a Zr(B,C,N) coated layer manufact ured by DC-pulse plasma-assisted chemical vapour deposition (PACVD) were in vestigated by thermal fatigue test. To examine the phase evolution and ther mal stress effect, cyclic thermal fatigue test was done, and X-ray diffract ion (XRD) and X-ray photoelectron spectroscopy (XPS) analyses were also per formed. Conclusions have been made as follows. The as-coated sample showed an amorphous structure, while monoclinic-ZrO2, tetragonal-ZrO2, and cubic-ZrO2 structures were formed after 20 h holding a t 700 degrees C. XPS analysis showed that in the as-coated sample, ZrO2-x s uboxide had already existed and carbon partially substituted Zr on Zr-O bon ding configuration. However, after 20 h holding at 700 degrees C, the subox ide disappeared and boride was formed. As for the thermal stress effect, th e fraction of the stable monoclinic phase increased as the heat treatment t ime increased without thermal stress. On the other hand, after cyclic therm al stress, the formation of a monoclinic phase was retarded. (C) 1999 Elsev ier Science S.A. All rights reserved.