Evaluation of duplex coatings produced with a pulsed Nd:YAG laser and filtered arc

Duplex coatings combining a physical vapour deposition (PVD) thin film and laser-clad WC/Ni layer were produced on an austenitic steel substrate. PVD TiN, TiCN and TiC thin films were deposited using a filtered arc deposition system. Laser-clad WC/Ni layers were produced using a pulsed Nd:YAG laser and optical fibres. Mechanical properties (microhardness and adhesion) of the coatings were determined using a Ultra-Micro Indentation System (UMIS-2000) and adhesion scratch tester, respectively. The wear resistance of the duplex coatings was evaluated by a pin-on-disc wear tester. The results showed that increasing the concentration of carbon in the PVD thin films increases its hardness, reduces its adhesion to the clad layer and increases its wear resistance. All coatings withstood the applied loads (25 and 40 N) and no sign of breakthrough was observed on any of them. This indicated that the duplex coatings exhibited a significant increase in load-bearing capacity, confirming the pivotal role of the laser-clad layer in supporting the applied load.