Enhancement of metallic glass properties of Cu-based BMG coating by shroud plasma spraying

In this study, nitrogen shrouded plasma spraying (SPS) was employed as a technique to minimize the oxidation and crystallization of bulk metallic glasses. To compare coatings prepared using the SPS technique with atmospheric plasma sprayed (APS) bulk metallic glasses, the deposition behaviors, and oxidation- and heat-induced crystallization mechanisms of APS and SPS Cu-based BMGs were studied in light of the results from different characterization techniques. Coatings prepared with the APS technique contained a considerable crystal fraction due to un-melted particles exposed to temperatures above the crystallization temperature, and oxidation phenomena which led to a reduction in glass forming ability (GFA). Oxidation and crystallization were controlled using the SPS process as an alternate technique that led to better corrosion resistance properties. The amorphous fraction of the SPS coating increased to 91.3% from 72% which is the fraction in APS.