Effect of interlayer coating thickness on the hardness and adhesion for the tungsten carbide cutting tool

Abstract EN

The thin film of the (Al,Ti)N coating is studied with the aid of two parameters: hardness and adhesion.

These parameters are very close to each other; however, in deposition field they could be interpreted differently.

Several coatings of (Al,Ti)N layers are developed on tungsten carbide insert using the standard commercial Al0.67Ti0.33 cathodes in cathodic arc plating system(PVD).

The influence of coating layer thickness on the mechanical properties of the coatings was investigated via two parameters: hardness and adhesion are characterized by the Rockwell tester Vickers tester.

The measurements reveal that the highest hardness appears for the (Al,Ti)N thickness of 5.815 µm while the highest adhesion appears at a thickness of 3.089 µm.

At the opposite extreme, the lowest hardness appears at 2.717 µm and the lowest hardness at 5.815 µm.

Overall, the (Al/Ti) N coating of the thickness of 5.815 µm is controversial as it exhibits the highest hardness and the lowest adhesion.

This result could be related to the effect of the formation of the micro-particle (MPs) which has a direct effect on the hardness because these MPs appear mainly on the surface and their presence at the interface is very limited.

In addition, the creation of Ti buffering layer to reduce the delamination has its major effect on the adhesion but has no effect on the morphology of the surface.

For these two reasons and the effect of the bias voltage, the results presented in this paper might show slight differences with other published papers.

The composition of the (Al,Ti)N layer is characterized and, seemingly, it shows one important result which is showing that the ultimate composition of the (Al,Ti)N layer (Ti0.62Al0.38) is very close to the original target used in this study (Al0.67Ti0.33).