Effect of bias voltages and interlayer design on microstructure, mechanical properties, and adhesion performance of AlCrSiN coatings deposited using HiPIMS

Abstract

This study fabricated AlCrSiN coatings from six alloy targets (Four Al7Cr3 targets and two Cr9Si1 targets) using high-power impulse magnetron sputtering (HiPIMS) with a focus on the effects of substrate bias voltage (−30 to −90 V) on deposition rate, microstructure, crystal orientation, residual stress, and mechanical properties. Electron Probe Microanalysis (EPMA) and X-ray Diffraction (XRD) results revealed that variations in bias voltage had little impact on the element composition or crystal structure (FCC) of AlCrSiN coatings; however, under high bias voltage (exceeding −60 V), the preferred orientation shifted from the (111) plane to the (220). Increasing the bias voltage from −30 to −90 V was shown to reduce the deposition rate (from 42.2 to 37.6 nm/min) and the thickness of the AlCrSiN coating (from 2.9 to 2.6 μm). It was also shown to increase the hardness (from 2147 to 3658 HV) and residual stress (from −0.01 to −0.59 GPa) by reducing the grain size and allowing the formation of a denser structure. Various interlayer designs (AlCr/AlCrxNy/AlCrN, CrSi/AlCrxNy/AlCrN, AlCr/CrSixNy/CrSiN, CrSi/CrSixNy/CrSiN) were assessed in terms of adhesion strength between the AlCrSiN and substrate. Under the same AlCrSiN deposition condition, with the bias voltage set to −60 V, the highest adhesion strength (from 32.28 to 45.81 N) was achieved using a CrSi/CrSixNy/CrSiN interlayer structure.