Study on the Formation of (Co,Ni)O Solid Solution and Metallic Ni Phases During Suspension Plasma Spraying of CoO and NiO Powders

SPS-sprayed (Co,Ni)O coating was investigated as a potential material for inert anode applications in Al production. In-flight particles were collected in water and splats formed on heated smooth metal substrates were captured to gain further insight into the melting and mixing of NiO and CoO powders during spraying. SEM, EDS, and x-ray diffraction analyses contributed to understanding the formation of different crystalline phases within the as-sprayed coatings. It was found that the intermixing of NiO and CoO to form (Co,Ni)O solid solution mainly occurs on the substrate surface, rather than in-flight, while keeping the substrate temperature high. The metallic nickel phase could be formed in the coatings in addition to the (Co,Ni)O solid solution phase. Accordingly, this study discussed in detail the possible causes for the formation of metallic Ni during spraying.

Automated summary

SPS-sprayed (Co,Ni)O coating was investigated as a potential material for inert anode applications in Al production. In-flight particles and splats formed on heated metal substrates were studied to understand the melting and mixing of NiO and CoO powders during spraying. SEM, EDS, and x-ray diffraction analyses helped clarify the formation of different crystalline phases in the coatings. The intermixing of NiO and CoO primarily occurred on the substrate surface, while the metallic nickel phase could also form in the coatings.