Abstract No.:
6396

 Title:
Improvement in adhesive strength of plasma spray ceramic coating by pre-treatment of dry-ice blasting

 Authors:
Yalda Asgari* / PARTO, Iran
Yalda Asgari / MAPNA Turbine Blade Engineering & Manufacturing Co. - PARTO, iran
Mahdi Bozorgnezhad/ MAPNA Turbine Blade Engineering & Manufacturing Co. - PARTO, iran
Ali Bakhshi/ MAPNA Turbine Blade Engineering & Manufacturing Co. - PARTO, iran

 Abstract:

With the aim of improving coating quality, in this study, dry-ice blasting, as an environmental-friendly method, is applied in APS process as a pre-treatment of YSZ coating to improve the bonding strength at the bond coat/top coat interface. The TBC systems were produced by atmospheric plasma spraying using a Sulzer-Metco F4 plasma gun. Dry-ice blasting was employed during part of the coating preparation processes and was carried out using a mobile blasting device. Two different sets of TBCs were prepared, first set with conventional bond coat/top coat by APS, while the top coat of the second group samples sprayed by APS with dry-ice blasting. Ice- blasting application was involved 5 passes before starting the ceramic layer deposition process. The aim was to clean the bond coat surface and obtain the appropriate bonding between the bond coat and top coat. The cross-sectional microstructure of the coating was examined by scanning electron microscopy (SEM). Roughness measurement was carried out before and after ice-blasting. The tensile adhesive strength was measured according to ASTM C633-01. Thermal shock tests were conducted to examine and compare the durability of samples. Results showed that the adhesive strength of ceramic coating deposited with dry-ice blasting nearly increased by 30% compared with that of the coating deposited with the conventional method. By comparing the average lifetimes of the TBCs in this study, it can be considered that first group Sample (TBC with APS dry-iceblasted) is the most durable and exhibits significant improvement in the lifetime as compared to sample with traditional APS sprayed top coat. The prolonged lifetime of TBCs produced with dry-ice blasting is attributed to the cleaning effect and the mechanical effect of dry-ice blasting, and to the remarkable decrease in the oxide content on the bond coat surface.



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