Ti/Ti-N Hf/Hf-N and W/W-N multilayer films with high mechanical hardness

Ti/Ti-N, Hf/Hf-N, and W/W-N multilayer films with very thin individual metal and metal-nitride layers were developed, with hardness of the structure much higher than that of single-layer nitride films. Hardnesses with value between 3500 and 5000 kg/mm2 or higher were observed in the multilayer films. This is an improvement over that of single-layer metal-nitride films where hardnesses between 2200 and 2800 kg/mm2 are typically achieved. The improvement is thought to be due to the fact that the grains are restricted to a very small size in the thin individual layers of the sandwich structure. The multilayer films, in general, have better adhesion and less defects than the single-layer films. These films were prepared on room-temperature substrates by a simple sputtering process and have potential applications, as in hard coatings.