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| Abstract No.: |
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Scheduled at:
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Wednesday, May 04, 2022, Hall D 10:50 AM
Aviation Industry I
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| Title: |
Porous APS YSZ TBC manufactured at high powder feed rate (100 g/min) and deposition efficiency (70%): Microstructure, bond strength and thermal gradients
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| Authors: |
Rogerio Lima* / National Research Council Canada, Canada
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| Abstract: |
The high-enthalpy APS torch Axial III Plus was employed to successfully manufacture a TBC by spraying a commercial YSZ feedstock at powder feed rate of 100 g/min using an optimized set of N2/H2 spray parameters that yielded an impressive YSZ deposition efficiency (DE) value of 70%. This exact same set of optimized spray parameters was used to manufacture the same identical YSZ TBC (over ~160 µm-thick bond-coated substrates) but at two distinct YSZ thickness levels: (i) ~420 µm-thick and (ii) ~930 µm-thick. In spite of the high YSZ feed rate and DE levels, the YSZ TBC revealed a ~14% porous (conventional looking) microstructure, without segmented cracking or horizontal delamination at both thickness levels. The bond strength values measured via the ASTM C633 standard for the ~420 µm-thick and ~930 µm-thick YSZ TBCs were ~13.0 and ~11.6 MPa (respectively); which are among at the upper end values reported in the literature. After the 1st objective was attained, the 2nd key objective of this work was to measure and report the thermal gradient values across these two TBCs. A thermal gradient laser-rig was employed to generate a temperature gradient along the TBC-coated coupons under different laser power levels. The YSZ surface temperature (T-ysz) and that of the substrate (T-sub) were measured. For the ~420 µm-thick YSZ TBC at a T-ysz range from 1100oC to 1500oC, the T-sub values obtained stretched from 750oC to 1000oC. For the ~930 µm-thick YSZ TBC at a T-ysz range from 1100oC to 1680oC, the T-sub values extended from 600oC to 880oC; i.e., a remarkable substrate temperature reduction 800oC. The results of this work are promising regarding the possibility of improving considerably the manufacturing efficiency of industrial quality conventional-looking porous YSZ TBCs by using a high-enthalpy N2-based APS torch.
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