THE MECHANICAL AND TRIBOLOGICAL PROPERTIES OF TITANIUM NITRIDE COATINGS FORMED IN A 4 MAGNETRON CLOSED-FIELD SPUTTERING SYSTEM

Titanium nitride coatings have been deposited on to tool steel substrates of three different roughnesses using four unbalanced rectangular planar magnetrons arranged in a closed field configuration. The composition and morphology of the films have been investigated using X-ray diffraction and scanning electron microscopy, and their mechanical properties have been characterised by scratch testing and microhardness measurement. The tribological properties have been established by pin on disc testing against hemispherical tungsten carbide pins, using relocation profilometry to provide accurate measurements of wear depths less than the original surface roughness. The films are stoichiometric TiN and have fully dense, non-columnar microstructures. Both the hardness and the wear resistance have been shown to increase substantially as the substrate surface roughness decreases. Good correlation of the mechanical and tribological properties is reported.