Synthesis of Layered Coatings from Solid Solutions of Niobium, Zirconium and Titanium Carbides on Hard Alloy Tool using Vacuum ARC Deposition

Abstract

Layered carbide coatings were formed on a carbide tool as a result of ion exposure by niobium cathode-arc source with energy of 1 keV and subsequent cathodic arc-vacuum deposition (CAVD) of coatings using simultaneous plasma flows of Nb and Zr, Nb and Ti in a methane atmosphere. The aim of the work was to study the phase and element composition, microhardness, adhesive strength, wear resistance and microstructure of a system of layered refractory carbide coatings formed on a WC-Co hard alloy. As a result, it was established, that vacuum cathode-arc deposition with simultaneous combustion of two metal cathodes Nb and Zr, or Nb and Ti with preliminary intense ionic action of Nb forms layered coatings on the hard alloy from solid solutions (Nb,Zr)C, (Nb,Ti)C and a sublayer of (W,Nb)C. The uppermost layer a few microns thick is solid solutions of carbides (Nb,Zr)C or (Nb,Ti)C. Between it and the hard alloy there is a thinner layer (Nb,W)C with a thickness of up to 0.5 μm. The hardness, flaking critical load of these layered coatings from solid carbide solutions is very high (58-65 GPa), (110-140 N). The volumetric wear of the tool with these carbide coatings is 4-10 times less than the wear of the hard alloy without coating