Deposition of HVAF-sprayed Ni-based amorphous metallic coatings

Ni53Nb20Ti10Zr8Co6Cu3 (at.%) amorphous alloy with high glass forming ability (GFA), capable of forming a wholly amorphous rod of ∼3 mm diameter by casting, was adopted to deposit amorphous metallic coatings by high velocity air fuel (HVAF) thermal spraying. The effects of powder feed rate and spraying distance on amorphous phase content and porosity of the coatings were investigated. It was indicated that an appropriate powder feed rate was desirable to produce a coating with high amorphous fraction, whereas a larger spraying distance led to a more dense coating. The corrosion resistance of the sprayed coatings was also examined in 1 M HCl aqueous solution.