Nitride hard coatings made from titanium aluminium nitride (TiAlN) protect drill bits, milling cutters and indexable cutting inserts against premature failure due to wear. Austria’s Plansee SE has reported that small quantities of tantalum have been shown to improve the thermal stability of these adherent layers still further.
TiAlN coatings are often doped with other elements to optimise the properties for a specific application, states Plansee. Thus, for instance, tantalum makes cutting operations even easier at high temperatures. Particularly when machining extremely hard materials, the tools are quickly liable to overheat.
Wear-protection coatings made from titanium aluminium tantalum nitride offer even better high-temperature stability and resistance to oxidation. This is said to make machining operations possible at temperatures of up to 950°C.
Plansee reported that the Institute of Materials Science and Technology at the Vienna University of Technology conducted a detailed investigation of the properties of titanium aluminium tantalum nitride coatings. The research team carried out trials with coatings made from titanium, aluminium and tantalum in different compositions.
The greatest thermal stability was achieved in the trials with a specific composition of materials (Ti0.32 Al0.6 Ta0.08N). The Powder Metallurgy technology used at Plansee to produce the necessary targets makes it possible to manufacture products with this precise composition of materials.