Degradation of thermal barrier coatings(TBCs) caused by calcium-magnesium-aluminasilica(CMAS) glassy penetration is becoming an urgent issue for TBCs industrial applications. In this work, yttrium aluminum garnet(YAlO...Degradation of thermal barrier coatings(TBCs) caused by calcium-magnesium-aluminasilica(CMAS) glassy penetration is becoming an urgent issue for TBCs industrial applications. In this work, yttrium aluminum garnet(YAlO, YAG) nano-powders were synthesized through a chemical co-precipitation route. The resistance of YAG ceramic to glassy CMAS infiltration at1250 °C was evaluated. YAG ceramic bulk sintered at 1700 °C for 10 h was comprised of a single garnet-type YAlOphase. The molten CMAS glass was suppressed on the surface of the YAG ceramic at 1250 °C. A chemical reaction between YAG and the molten CMAS glass did not occur at 1250 °C for 24 h, suggesting that YAG could act as an impermeable material against glassy CMAS deposits in the TBC field.展开更多
A β--NiAI alloy with normal purity, a S-doped and a Dy and S co-doped （Y-NiAI alloys were prepared by arc-melting and their corresponding S contents were less than 20 ×10-6, 33 ×10-6 and 22 × 10-6, re...A β--NiAI alloy with normal purity, a S-doped and a Dy and S co-doped （Y-NiAI alloys were prepared by arc-melting and their corresponding S contents were less than 20 ×10-6, 33 ×10-6 and 22 × 10-6, respectively. The isothermal oxidation behavior of the alloys at 1200 ℃ was investigated and the extent of S segregation at the scale-alloy interface was determined by scanning Auger microscopy. S-doping had no significant effect on the phase transformation rate from e- to β-Al2O3, while the addition of Dy retarded this process. For the S- doped alloy, scale rumpling occurred only after 2 h thermal exposure and numerous large voids were observed at the scale-alloy interface where S segregated. In contrast to this, the oxide scale formed on the Dy and S co-doped alloy still remained flat even after 50 h isothermal oxidation and only small voids existed at the interface where S segregation was not detected.展开更多
As potential thermal barrier coating （TBC） materials, Ruddlesden-Popper structured BaLn2Ti3010 （Ln = rare earth） compounds possess excellent phase stability and desirable thermo-physical properties as well as inte...As potential thermal barrier coating （TBC） materials, Ruddlesden-Popper structured BaLn2Ti3010 （Ln = rare earth） compounds possess excellent phase stability and desirable thermo-physical properties as well as interesting anisotropic structure. In this paper, the effects of pressure during BaLa2Ti3010 （BLT） bulk preparation on the grain orientation were investigated. BLT grains exhibited lamellar structure, but the grain orientation depended strongly on the existence of pressure during bulk preparation. When pressure was applied, BLT grains preferentially grew along pressing direction, leading to formation of the texture parallel to pressing direction, but BLT grain orientation became relatively random when pressure was absent. However, in the small scale area, BLT grains grew preferentially along c-axis with independence on pressure during preparation. Pressure affected BLT grain orientation at the rapid growth stage according to the grain growth model of BLT.展开更多
基金sponsored by the National Natural Science Foundation of China(NSFC)No’s.51590894,U1537212,51425102,51231001,51471019,and 51271011
文摘Degradation of thermal barrier coatings(TBCs) caused by calcium-magnesium-aluminasilica(CMAS) glassy penetration is becoming an urgent issue for TBCs industrial applications. In this work, yttrium aluminum garnet(YAlO, YAG) nano-powders were synthesized through a chemical co-precipitation route. The resistance of YAG ceramic to glassy CMAS infiltration at1250 °C was evaluated. YAG ceramic bulk sintered at 1700 °C for 10 h was comprised of a single garnet-type YAlOphase. The molten CMAS glass was suppressed on the surface of the YAG ceramic at 1250 °C. A chemical reaction between YAG and the molten CMAS glass did not occur at 1250 °C for 24 h, suggesting that YAG could act as an impermeable material against glassy CMAS deposits in the TBC field.
基金supported by the National Natural Science Foundation of China (NSFC) under Grant Nos. 51071013 and 51231001the National Basic Research Program (973 Program) of China under Grant Nos. 2010CB631200 and 2012CB625100
文摘A β--NiAI alloy with normal purity, a S-doped and a Dy and S co-doped （Y-NiAI alloys were prepared by arc-melting and their corresponding S contents were less than 20 ×10-6, 33 ×10-6 and 22 × 10-6, respectively. The isothermal oxidation behavior of the alloys at 1200 ℃ was investigated and the extent of S segregation at the scale-alloy interface was determined by scanning Auger microscopy. S-doping had no significant effect on the phase transformation rate from e- to β-Al2O3, while the addition of Dy retarded this process. For the S- doped alloy, scale rumpling occurred only after 2 h thermal exposure and numerous large voids were observed at the scale-alloy interface where S segregated. In contrast to this, the oxide scale formed on the Dy and S co-doped alloy still remained flat even after 50 h isothermal oxidation and only small voids existed at the interface where S segregation was not detected.
基金sponsored by the National Natural Science Foundation of China(Nos.51071013 and 51231001)the National Basic Research Program of China("973 Program",No.2012CB625100)
文摘As potential thermal barrier coating （TBC） materials, Ruddlesden-Popper structured BaLn2Ti3010 （Ln = rare earth） compounds possess excellent phase stability and desirable thermo-physical properties as well as interesting anisotropic structure. In this paper, the effects of pressure during BaLa2Ti3010 （BLT） bulk preparation on the grain orientation were investigated. BLT grains exhibited lamellar structure, but the grain orientation depended strongly on the existence of pressure during bulk preparation. When pressure was applied, BLT grains preferentially grew along pressing direction, leading to formation of the texture parallel to pressing direction, but BLT grain orientation became relatively random when pressure was absent. However, in the small scale area, BLT grains grew preferentially along c-axis with independence on pressure during preparation. Pressure affected BLT grain orientation at the rapid growth stage according to the grain growth model of BLT.
