Fig. 1. Surface and cross-section morphologies of as-sprayed thermal barrier coatings. (a) Surface morphology; (b) surface morphology at high magnification; (c) cross-section morphology; (d) cross-section morphology of 8YSZ ceramic coating at high magnification

Fig. 2. Surface and cross-section morphologies of laser-alloyed thermal barrier coatings. (a) Surface morphology; (b) surface morphology at high magnification; (c) cross-section morphology; (d) cross-section morphology at high magnification

Fig. 3. XRD patterns of 8YSZ powder, as-sprayed thermal barrier coating and laser-alloyed thermal barrier coatings. (a) 8YSZ powder; (b) as-sprayed thermal barrier coating; (c) laser-alloyed thermal barrier coating

Fig. 4. Surface morphology and its high magnification of as-sprayed thermal barrier coatings after 4 h hot corrosion at 900 ℃. (a) 500×; (b) 10000×

Fig. 5. XRD patterns of as-sprayed and laser-alloyed thermal barrier coatings after molten salt corrosion. (a) As-sprayed thermal barrier coating; (b) laser-alloyed thermal barrier coating

Fig. 6. Surface morphology and its high magnification of laser-alloyed thermal barrier coating after 4 h hot corrosion at 900 ℃. (a) 500×; (b) 5000×

Fig. 7. Cross-section morphology and EDS element analysis of as-sprayed thermal barrier coating after 4 h hot corrosion. (a) Cross-section morphology; (b) EDS elemental analysis

Fig. 8. Cross-section morphology and EDS element analysis of laser-alloyed thermal barrier coating after 4 h hot corrosion. (a) Cross-section morphology; (b) EDS elemental analysis

Fig. 9. Schematics of hot corrosion failure of as-sprayed and laser-alloyed thermal barrier coatings. (a) As-sprayed thermal barrier coating before hot corrosion test; (b) as-sprayed thermal barrier coating after hot corrosion test; (c) laser-alloyed thermal barrier coating before hot corrosion test; (d) self-healing process of laser-alloyed thermal barrier coating; (e) laser-alloyed thermal barrier coating after hot corrosion test

Table 1. Chemical composition of nickel-based superalloy Inconel 718

Table 2. Process parameters of atmospheric plasma spraying

Table 3. Chemical composition of different areas in as-sprayed thermal barrier coating after hot corrosion