A review on nanostructured WC–Co coatings

Unique mechanical properties of nanostructured materials motivate a worldwide interest to synthesize nanostructured coatings. Nanostructured WC–Co coatings have been extensively investigated because of the importance of WC–Co coatings in industrial applications, usually with respect to wear resistance requirements. The present paper has reviewed the studies in this field, including synthesis of nanostructured WC–Co powder, concern on decomposition of nanostructured WC particles, influence of spraying parameters on microstructure and mechanical properties of nanostructured coatings. Significant achievements in this field are: (1) It is possible to produce nanostructured WC–Co powders without non-WC/Co phases in quantities although a high percentage of non-WC/Co phases is frequently reported in conventional WC–Co powder; (2) By controlling agglomerate size of feedstock powder, fuel chemistry and fuel–oxygen ratio, the decomposition of WC particles can be reasonably eliminated so as to synthesize near nanostructured WC–Co coating with a low amount of non-WC/Co phases; and (3) Increased hardness, toughness and wear-resistance can be obtained in near nanostructured WC–Co coatings that are properly synthesized.