Vysokoteplotní nízkocyklová únava lité niklové superslitiny Inconel 713LC povlakované ZrO2 -SiO2 -Al2O3 nanokrystalickou termální bariérou

High temperature low cycle fatigue behavior of cast superalloy Inconel 713LC coated with ZrO2 -SiO2 -Al2O3 nanocrystalline thermal barrier coating

abstrakt

en

Cast polycrystalline nickel base superalloy Inconel 713LC is used for production of blades and discs of gas turbine engines that are subjected to repeated elastic-plastic loading in aggressive environments at variable temperatures. Thermal barrier coatings (TBCs) consist of thermally insulating ceramic top coat and of a metallic oxidation/corrosion-protective bond coat. They can prolong the component life particularly by a reduction of temperature gradient during heating and cooling. In the present work, the high temperature low cycle fatigue behavior of cast nickel-based superalloy Inconel 713LC in as-received state and coated with novel Al2O3-SiO2-ZrO2/CoNiCrAlY TBC system was studied at the temperature of 900 °C. The microstructure of the substrate material consisted of dendritic grains with carbides and shrinkage pores. The average grain size was 0.66 mm. The novel TBC system consists of a (inter)metallic CoNiCrAlY bond coat and a eutectic ceramic, i.e. zirconia (ZrO2), alumina (Al2O3) and silicia (SiO2) top coat deposited on the gauge section of cylindrical specimens using atmospheric gas stabilized plasma and water stabilized plasma, respectively. Due to the system of eutectic ceramic coupled with high temperature developed by using water stabilized plasma the top coat was formed in partially crystalline phase. Its subsequent heat treatment enabled to produce the nanocrystalline mullite phase in the remaining mostly ZrO2 and Al2O3 coating matrix. Button-end samples with dimensions close to the final specimens were manufactured using investment-casting. Cylindrical specimens of Inconel 713LC in as-received condition and with TBC surface treatment were cyclically strained under strain control with constant total strain amplitude in symmetrical cycle at 900 °C in air. The microstructure of the surface treated layer was documented and the hardness of the layers was evaluated. Hardening/softening curves, cyclic stress-strain curve and fatigue life data of coated and uncoated material were obtained. The fracture surface, surface relief and polished sections parallel to the specimen axis were examined using optical microscopy and SEM to study damage mechanisms in cyclic loading at high temperature. The microstructural and degradation mechanisms data help to discuss the differences in the stress-strain response and fatigue life of both materials.

Cast polycrystalline nickel base superalloy Inconel 713LC is used for production of blades and discs of gas turbine engines that are subjected to repeated elastic-plastic loading in aggressive environments at variable temperatures. Thermal barrier coatings (TBCs) consist of thermally insulating ceramic top coat and of a metallic oxidation/corrosion-protective bond coat. They can prolong the component life particularly by a reduction of temperature gradient during heating and cooling. In the present work, the high temperature low cycle fatigue behavior of cast nickel-based superalloy Inconel 713LC in as-received state and coated with novel Al2O3-SiO2-ZrO2/CoNiCrAlY TBC system was studied at the temperature of 900 °C. The microstructure of the substrate material consisted of dendritic grains with carbides and shrinkage pores. The average grain size was 0.66 mm. The novel TBC system consists of a (inter)metallic CoNiCrAlY bond coat and a eutectic ceramic, i.e. zirconia (ZrO2), alumina (Al2O3) and silicia (SiO2) top coat deposited on the gauge section of cylindrical specimens using atmospheric gas stabilized plasma and water stabilized plasma, respectively. Due to the system of eutectic ceramic coupled with high temperature developed by using water stabilized plasma the top coat was formed in partially crystalline phase. Its subsequent heat treatment enabled to produce the nanocrystalline mullite phase in the remaining mostly ZrO2 and Al2O3 coating matrix. Button-end samples with dimensions close to the final specimens were manufactured using investment-casting. Cylindrical specimens of Inconel 713LC in as-received condition and with TBC surface treatment were cyclically strained under strain control with constant total strain amplitude in symmetrical cycle at 900 °C in air. The microstructure of the surface treated layer was documented and the hardness of the layers was evaluated. Hardening/softening curves, cyclic stress-strain curve and fatigue life data of coated and uncoated material were obtained. The fracture surface, surface relief and polished sections parallel to the specimen axis were examined using optical microscopy and SEM to study damage mechanisms in cyclic loading at high temperature. The microstructural and degradation mechanisms data help to discuss the differences in the stress-strain response and fatigue life of both materials.

Cast polycrystalline nickel base superalloy Inconel 713LC is used for production of blades and discs of gas turbine engines that are subjected to repeated elastic-plastic loading in aggressive environments at variable temperatures. Thermal barrier coatings (TBCs) consist of thermally insulating ceramic top coat and of a metallic oxidation/corrosion-protective bond coat. They can prolong the component life particularly by a reduction of temperature gradient during heating and cooling. In the present work, the high temperature low cycle fatigue behavior of cast nickel-based superalloy Inconel 713LC in as-received state and coated with novel Al2O3-SiO2-ZrO2/CoNiCrAlY TBC system was studied at the temperature of 900 °C. The microstructure of the substrate material consisted of dendritic grains with carbides and shrinkage pores. The average grain size was 0.66 mm. The novel TBC system consists of a (inter)metallic CoNiCrAlY bond coat and a eutectic ceramic, i.e. zirconia (ZrO2), alumina (Al2O3) and silicia (SiO2) top coat deposited on the gauge section of cylindrical specimens using atmospheric gas stabilized plasma and water stabilized plasma, respectively. Due to the system of eutectic ceramic coupled with high temperature developed by using water stabilized plasma the top coat was formed in partially crystalline phase. Its subsequent heat treatment enabled to produce the nanocrystalline mullite phase in the remaining mostly ZrO2 and Al2O3 coating matrix. Button-end samples with dimensions close to the final specimens were manufactured using investment-casting. Cylindrical specimens of Inconel 713LC in as-received condition and with TBC surface treatment were cyclically strained under strain control with constant total strain amplitude in symmetrical cycle at 900 °C in air. The microstructure of the surface treated layer was documented and the hardness of the layers was evaluated. Hardening/softening curves, cyclic stress-strain curve and fatigue life data of coated and uncoated material were obtained. The fracture surface, surface relief and polished sections parallel to the specimen axis were examined using optical microscopy and SEM to study damage mechanisms in cyclic loading at high temperature. The microstructural and degradation mechanisms data help to discuss the differences in the stress-strain response and fatigue life of both materials.

Low cycle fatigue, thermal barrier coating

10.05.2015

141–141

1