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摘要
Thermal barrier coatings (TBCs) are employed to protect metallic components from heat, oxidation, and corrosion in hostile environments. In this paper Ni-20Cr bond coat followed by CaZrO(3) top coat was deposited on 316 stainless steel substrates by air plasma spray coating technique. Isothermal treatment of coated samples was carried out to investigate the effect of heat exposure on the microstructure and metallurgical phase changes of TBCs system. The fractured surface of as-sprayed and delaminated CaZrO(3) coatings was also studied to observe the splats morphology, structural defects, and lamellas internal microstructure. CaZrO(3) coating was found to be stable for 100 h at 700 A degrees C but accelerated degradation was observed at 900 A degrees C even at 20 h and lead to delamination after 60 h of exposure time. Chromium rich oxide formation was found to be responsible for the complete delamination of the top coat. Further, the formation of meta-stable monoclinic phase was also observed on the top surface of the top coat.
- 出版日期2012-1
