Experimental study of the microscopic characteristics of Ti-Based Laser Cladding Ti＋7YSZ composite thermal barrier coatings.

• The microstructure of Ti/7YSZ composite coating is fine in the upper and lower part and thick in the middle part. • Zr element enriched in the bonding zone in the form of ZrC and solid solution.Innovation • The microhardness of the cladding zone is 2.5 times higher than that of TC4 matrix, and reaches the peak value at 7mm/s. Ti/7YSZ composite coating system was prepared on the surface of TC4 titanium alloy by laser cladding using YLS-3000 fiber laser system, The macroscopic feature, microstructure, element distribution and hardness distribution of Ti-Based Laser Cladding Ti＋7YSZ composite thermal barrier coatings were characterized by optical microscopy, scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). The results showed that Ti-based composite thermal barrier coating system changes the microstructure from top to bottom at different laser scanning speeds. It is mainly composed of acicular α' martensite, martensite core, α phase bundle and residual β phase, which has the characteristics of "Fine up and down, coarse in the middle". Due to surface tension, buoyancy, molten pool agitation and self-density. Zr element is enriched in the binding zone, and its signal intensity level increases first and then decreases as the scanning speed increases. Due to the dislocation slip resistance between the martensite and the solid solution strengthening effect of the Zr forming replacement solid solution, the hardness of the cladding zone is significantly higher than that of the structure, which is 2.5 times that of the TC4 structure. [ABSTRACT FROM AUTHOR]