Novel hardmetals with nano-grain reinforced binder for hard-facings

Ordinary hard-facings obtained by plasma spraying or thermal spraying are characterized by a combination of hardness, wear-resistance and fracture toughness inferior to that of conventional WC-Co hardmetals. Therefore, in the majority of applications they are incomparable with WC-Co materials and cannot substitute them. A fundamentally new approach to the fabrication of novel WC-based hardmetals in form of hard-facing obtained by PTA (plasma transferred arc) welding was elaborated. The microstructure of the novel hardmetals of the W-C-Fe-Cr-Si system depends on the plasma welding parameters and consists of carbide grains embedded in a Fe-based binder. The binder comprises hard nano-precipitates in form of nanoparticles of the η-type phases and mixed Cr-Fe carbides embedded in a Fe-based binder matrix. The wear-resistance of the novel hardmetals obtained in form of hard-facings is comparable with that of conventional WC-Co hardmetals fabricated by the powder metallurgy technology.