Hybrid Thermal Spray: A Pathway to Realize Novel Coating Microstructures and Properties

Thermal spray technology, a versatile coating technique, significantly impacts diverse industries and is pivotal in modern manufacturing processes. Like other technologies, it must continuously evolve to address new challenges and market demands. In this context, “hybrid thermal spraying” utilizing distinct feedstocks (such as powders, wire, suspensions, and solution precursors) offers a novel pathway to conveniently combine dissimilar materials at very different length scales to realize coatings with unique properties and enhanced performance. This approach seamlessly integrates into all thermal spray techniques. Introducing two or more distinct feedstocks simultaneously or sequentially with independent control over each can deposit coatings with varied architectures and novel microstructures. The present-day industry constantly demands enhanced performance and longevity of established wear-resistant coatings, thermal barrier coatings (TBCs), etc., and novel functionalities for emerging fields such as batteries. Hybrid thermal spray can potentially address these needs by elegantly combining established material systems with additional constituents. This review discusses the different variants of hybrid thermal spraying, and their relevance to practical applications is explored based on a comprehensive assessment of available literature. This review is intended to serve as a bridge between traditional and innovative approaches for inspiring further research to harness the advantages of hybrid thermal spray processes gainfully. It also discusses the challenges and limitations associated with this approach.