Deposition and characterization of nanostructured WC-Co coating

Nanostructured WC Co coatings were prepared with the vacuum plasma spraying process. The microstructure of the as-prepared coatings was determined wit h SEM, TEM and XRD. The results show that the main structure of the coating s is composed of WC grains with a mean particle size of 35 nm, which have a similar grain size to the primary powders. However, in some regions, the g rain size of WC is reduced to about 10 nm due to the melting of the WC-Co p owders. In some regions, WC grains are completely melted forming an amorpho us phase. In some regions, WC grains have grown to 100 nm; in other regions , the second recrystallization occurred, strip-shaped and square-shaped str uctures are formed, which are as large as 500 nm. The main phase of the as- preparcd WC Co coating is WC with minor phases of alpha -W2C, beta -WC1-x, and W3Co3C. The hardness of the coating is about 18 Gpa with a wide distrib ution. (C) 2001 Published by Elsevier Science Ltd and Techna S.r.l. All rig hts reserved.