High-rate pulsed reactive magnetron sputtering of oxide nanocomposite coatings

The article reports on the oxide nanocomposite coatings reactively sputtered by a pulsed dual magnetron and is divided into two parts. The first part briefly describes main problems in the reactive sputtering of oxides, i.e. low deposition rate a_D and arcing at the target surface and then focuses on the discharge of the dual magnetron. The ways how a_D can be increased and arcing eliminated are shown. The second part is devoted to transparent oxide coatings. Two types of oxide coatings are described in detail: (1) Si–Zr–O coatings containing ≤5 at.% of Zr and (2) Zr–Al–O coatings with Zr/Al > 1. It is shown that (a) Si–Zr–O coatings exhibit high thermal stability up to 1500 °C, almost 100% optical transparency and can be deposited with very high a_D ≈ 800 nm/min from a molten magnetron target and (b) Zr–Al–O coatings with relatively high hardness H ≈ 18–19 GPa, low effective Young’s modulus E¹ satisfying the ratio H/E¹ > 0.1 are highly elastic (the elastic recovery W_e > 70%) and exhibit an enhanced resistance to cracking. The last finding is of key importance for development of new hard coatings with enhanced toughness.