A new type of atomized coating powder for protection against wear and corrosion

Conventionally tailored hard alloys are dominated by binary borides and carbides or complex carbides. This paper discusses a new type of nickel-base alloy, the properties of which are governed by the presence of a complex ternary boride. This boride has a face-centred cubic structure and a composition range of Ni 20 – 21M 2 – 3B 6, where M is a group IV – Va metal used as a stabilizer. Extensive investigations of phase equilibria and diagrams have shown that these so-called τ-borides can be stabilized in chromium-containing alloys of nickel, refractory metal and boron as well as in ternary Ni-M-B systems (where M is titanium, vanadium, niobium or tantalum). Optimized alloys were chosen for powder production via vacuum melting and inert gas atomization. Finally, high quality powders ready for industrial application in various spraying techniques were made available. The paper discusses the properties of the alloys with regard to wear resistance, oxidation behaviour and corrosion.