Solid solution hardening of vacancy stabilized TixW1−xB2

AbstractWe present a combined experimental and theoretical investigation of sputter deposited thin films in the ternary system Ti1−xWxB2. Solid solutions of Ti1−xWxB2−z were prepared by physical vapor deposition (PVD) and, over the whole composition range, found to crystallize in the AlB2 structure type. The obtained films exhibit good thermal stability and high hardness, evidencing a maximum value of almost 40GPa for Ti0.67W0.33B2−z. The effect of vacancies on stabilization and mechanical properties of the AlB2 structure type is discussed, using ab initio simulations. Based on our results, we can conclude that vacancies are crucial for the phase stability of PVD deposited Ti1−xWxB2−z coatings

High-power-density sputtering of industrial-scale targets: Case study of (Al,Cr)N

Large-scale sputter-deposition of hard protective coatings has not been prevalent as the large dimensions of the industrial targets posed an enormous technological challenge: only relatively low power (and plasma) densities could be achieved, resulting ultimately in poor performance of such coatings. Here, we introduce a novel sputtering technology allowing to reach high power densities for industrial tubular targets. This is realised on the principle of a longitudinal movement of a reduced-size magnetron inside the target. In doing so, peak power densities of 840 W/cm2 have been achieved for the overall power of 25 kW and the target dimensions of Ø110 × 510 mm. To demonstrate the effectiveness of the solution, we produced a series of cubic (Al,Cr)N coatings by sputtering an Al60Cr40 target. Most of the coatings have a stoichiometric composition, smooth surface and a moderate amount of growth defects. Significant improvements through recipe optimisation could be achieved resulting in mechanical properties (hardness, fracture toughness, wear resistance) being equal to and even exceeding those of the benchmark coatings produced by means of conventional sputtering and cathodic arc evaporation. Our results open up great potential of this novel sputtering technique for the coating industry

Multilayer design of crN/MoN superhard protective coatings and their characterisation

Multilayer CrN/MoN transition metal nitride coatings were studied in this research. Films were deposited by vacuum arc deposition (Arc-PVD) from Cr and Mo cathodes in nitrogen atmosphere p = 0.4 Pa. Three series of samples with different values of negative bias voltage (−20, −150, and −300 V) applied to the surface were fabricated. Each series has samples with 11, 22, 44, 88, 180 and 354 layers while total thickness was maintained with the same value. Samples were studied by scanning electron microscopy (SEM) on cross-sections and coatings surface, energy-dispersive X-ray spectroscopy (EDS), electron backscatter diffraction (EBSD), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), micro-indentation. Two main cubic phases of γ-Mo N and cubic CrN were detected. It was observed that the crystal growth orientation changes while the negative bias voltage of the substrate decreases. The maximum values of hardness (38–42 GPa) among the studied samples were obtained for coatings with a minimal individual layer thickness of 20 nm deposited at U = −20 V. N 2 bFCT - Sumy State University(0116U002621). Foundation of Science and Technology (FCT) of Portugal [references NORTE-01- 0145-FEDER-022096, SFRH/BD/129614/2017], Network of Extreme Conditions Laboratories (NECL) and by Ukrainian state budget programs [No. 0116U006816, 0118U003579 and 0116U002621]. Partial support by COST Action CA15102 is also greatly appreciate