Improved microstructure and properties of cold sprayed zinc coatings in the as sprayed condition

Abstract

Cold sprayed zinc coatings have the potential to provide barrier as well as sacrificial protection to steels. In the present work, zinc coatings were deposited on mild steel substrate and its microstructure and properties such as hardness, elastic modulus and corrosion performance were evaluated. Owing to the purity of the feedstock and use of anti-clogging nozzle, improved microstructure and properties especially corrosion resistance were achieved in the as sprayed condition itself obviating the need for a cost and time consuming post treatment. In addition to this, a property and microstructure comparison was made with zinc coatings deposited using other spray techniques such as wire arc spray and flame spray. It was found that cold sprayed coatings fared better than their counterparts from other techniques in the as sprayed condition itself. Improved inter-splat bonding was one of the major reasons for the superior performance of cold sprayed coatings. An indirect inference was also found from the elastic modulus of the coatings wherein cold sprayed coatings had higher modulus than other coatings. An attempt was also made to analyze the results from Finite element (FE) approach.