Hard yet tough Ti-TiN nanocomposite coatings

Nanocomposite Ti-TiN coatings were deposited on Si (100) substrates using pulsed DC magnetron sputtering as a function of Ti metal content. Structural and microstructural characterizations of the as-deposited coatings were carried out using X-ray diffraction and field emission scanning microscopy. Nano-mechanical properties of the coatings were evaluated using nanoindentation, scratch and wear testing techniques. It was observed that nano-hardness and elastic modulus of the coatings decreased with an increase in Ti content. The H/E ratio, an indicator of wear resistance, was found to vary from 0.074 to 0.101 for the coatings with low Ti content. A linear increase in fracture toughness from 1.19 to 2.75 MPa.m1/2 with increasing Ti content was observed. However, the coating with highest fracture toughness value did not reveal good wear resistance. The coating with a Ti content of 63.3% was found to be optimised for wear resistant applications with a fracture toughness of 2.12 MPa.m1/2 and nano-hardness of around 17.5 GPa