Functionally graded WC–Ti(C,N)–(Ta,Nb)C–Co hardmetals: Metallurgy and performance
Abstract The thermodynamic and kinetic aspects of tailoring the near-surface zones of functionally graded hardmetals (FGHM) by nitrogen management are described and summarised. Since, as a result of the development process, industrial production as well as a broad usage as cutting tools is aimed, the focus is put on testing of coated FGHM substrates. Testing was performed by individual in-house tests, systematic tests in an application laboratory as well as in a production environment (turning of stamping punches). FGHM grades with carbonitride-enriched surface zones proved to outperform other grades significantly. Diamond coatings on FGHMs show excellent adhesion as well as abrasion resistance, actually the best of all tested grades. In continuous turning operations of steel, both flank and crater wear resistance were improved significantly, and the tool life almost doubled in FGHM grades which show a carbonitride-enriched near-surface zone.