Characteristics of high-power impulse magnetron sputtering (HiPIMS) deposited nanocomposite-TiAlSiN coating under variable pulse frequencies

In the present study, nanocomposite-TiAlSiN coatings were deposited on WC-Co blocks using HiPIMS technology by varying pulse frequency. Its immediate effect on V-I signature and subsequent results on coating characteristics was critically investigated. Both substrate and target were negatively biased in pulsed mode but the voltage pulses on substrate was set with an offset of 40 mu s, with respect to those on targets to avoid gas ion entrapment within coating. Variation of elemental composition, cross-sectional morphology, surface topography, hardness, and adhesion strength of the coating deposited under different pulsed frequencies, were analyzed in depth. TiAlSiN at the highest frequency, showed significant improvements in hardness and scratch resistance. A significant rise in Lc3 was recorded to be from 137.5 to 158.5 N when the pulse frequency was increased from 1 to 4 kHz. On the other hand, the peak target current was found to decrease from 340 A to 106 A. XRD spectra of TiAlSiN showed a peak shift from AlN (200) to TiAlN (200). Higher deposition rates were achieved with higher frequency but a compromise on surface smoothness, which was measured (Sa) with an increase from 9.42 to 14.32 nm.