## 3 Results and Discussion  
### Microstructure of EMAP TBCs  
By changing the plasma-spraying process and introducing the second-phase MAPs, the microstructure of TBCs was changed. As shown in Figure 4a-h was the EMAP TBCs microstructure SEM diagram, Figure 4i is a conventional TBC. It can be observed from the microstructure SEM diagram that the EMAP TBCs have higher porosity than the conventional TBCs due to the introduction of the second-phase MAPs. Moreover, the pores of EMAP TBCs are more concentrated, which makes them have better sintering resistance. Figure 4a-h were the microstructure maps of EMAP TBC samples prepared by different plasma processes. Figure 4a-c EMAP TBCs were prepared by different distances between two powder feeders, and the distances between the two powder feeders were 30 mm, 35 mm, and 40 mm, respectively. Figure 4d-f were EMAP TBCs prepared by different powder feeding rates of powder feeder 1, and the powder feeder 1 rates were 12 g/min, 16 g/min, and 20/min, respectively. Figure 4g,h were EMAP TBCs prepared by different first-phase powders, respectively. The first-phase powder of Figure 4g was FC, and the first-phase powder of Figure 4h was MAP.  
The MAP microstructure feature extraction map in EMAP TBCs is shown in Figure 5, and the Weka Segmentation plug-in of ImageJ software was used to segment MAP features. As shown in Figure 5a, the yellow box was the MAP embedded in the conventional coating matrix, corresponding to the white area in Figure 5b. Subsequently, the content of MAPs in EMAP TBCs was calculated using the statistical tool included in Image J (Version 1.54a).  
Figure 4: Microstructure of EMAP TBCs and conventional TBCs. (**a**) EMAP TBCs6; (**b**) EMAP TBCs2; (**c**) EMAP TBCs4; (**d**) EMAP TBCs1; (**e**) EMAP TBCs2; (**f**) EMAP TBCs3; (**g**) EMAP TBCs8; (**h**) EMAP TBCs5; (**i**) conventional TBCs1.  
In this work, for the reliability of the test results, three tests were sprayed on each group of parameters. Two SEM images were taken from each test to calculate the proportion of MAPs in EMAP TBCs. The statistical results are shown in Figure 6. The groups a-h correspond to the SEM diagram and its process parameters in Figure 3. It can be clearly seen from Figure 5 that as the distance between the two powder feeders increases from 30 mm to 40 mm, the MAP ratio gradually increases. When the distance between the two powder feeders was 30 mm, the powder feeder 2 was close to the plasma flame flow. After the MAP was fully sintered, the proportion of MAPs was the lowest, which reduces the porosity of the coating and reduces the anti-sintering performance of the coating. When the distance between the powder feeders was 40 mm, the powder feeder 2 was too far away from the plasma flame flow, and the MAPs cannot be properly sintered. The proportion of MAPs was too high, and the coating had high porosity, which reduced the fracture toughness of the coating. When the distance between the powder feeders was 35 mm, MAPs were slightly sintered to maintain an appropriate proportion and have high sintering resistance and fracture toughness. In addition, it can be observed that with the increase in the rate of powder feeder 1, the proportion of the first-phase powder increases, which makes the content of MAPs in EMAP TBCs gradually decrease. Comparing the two-phase powder feeder powder using the different ceramic powders, it can be seen that the use of micron-agglomerated powder has a higher MAP ratio than the melt-broken powder.