Which powders for cold spray?

Since the major technological issues in cold spray are now controlled, the key parameter for successful coating relates to the powder. The influence of the main characteristics of the starting powder on the final coating properties remains rather unknown. This includes primarily metallurgical, morphological and physico-chemical characteristics of the particles. This article focuses on the so-called local approach to these characteristics to show that the current global approach is insufficient. The discussion is based on many examples of cold spray results, including recent work on Ag-based and Ta cold sprayed-coatings. This results in proposed specifications for powders which are claimed to be tailored for cold spray.