Recent Progresses in Thermal‐Sprayed Lead‐Free Piezoelectric Ceramic Coatings for Structural Health Monitoring

ABSTRACT Thermal spray deposition shows potential value for producing lead‐free piezoelectric ceramic coatings owing to its high deposition rate, large‐area coverage, and suitability for open‐environment processing. These attributes make thermal spray process particularly appealing for structural health monitoring (SHM), where scalable and large‐scale environmentally friendly transducer integration is essential. Starting from a brief introduction to the principles of thermal spray, this review summarizes the recent progresses in the thermal spray fabrication of lead‐free piezoelectric coatings, after the first success in obtaining potassium sodium niobate (KNN)‐ and bismuth sodium titanate (BNT)‐based piezoelectric ceramic coatings using this method. The ultrasonic transducers enabled by the thermal‐sprayed lead‐free piezoelectric coatings for SHM are highlighted. The major challenges and future opportunities for advancing thermal‐sprayed piezoelectric coatings toward SHM applications are discussed.