Comparison of Al-Si-N nanocomposite coatings deposited by HIPIMS and DC magnetron sputtering

• This paper presents a comparative study between DC magnetron sputtering (DCMS) and high power impulse magnetron sputtering (HIPIMS) of Al-Si-N. Coatings were synthesised through co-sputtering of Al and Si in a mixed Ar/N-2. One set of DCMS experiments and one set of hybrid HIPIMS (Al-target)/DCMS (Si-target) experiments were conducted. It was found that a higher partial pressure of N-2 was necessary to obtain fully nitrided material using the HIPIMS process. The Si content of the samples was varied between 0 and 16 at.%. All processes were characterised using optical emission spectroscopy (OES) as well as energy-resolved mass spectrometry (E-MS). The obtained coatings were characterised using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), as well as UV-Vis spectroscopy and nanoindentation. The HIPIMS processes were found to provide a highly activated growth environment, with Al+ comprising 87% of the total ion flux, compared to 0.6% for the DCMS case, where Ar+ was found to be the dominating species comprising 90% of the total ion flux. Coatings from both HIPIMS and DCMS processes were found to form nanocomposites of a solid solution phase (Al1-xSix)N and most likely a SiN, phase, as shown by XRD and XPS analyses. Compared to coatings from DCMS, samples deposited with HIPIMS had a slightly more textured AlN-phase with smaller grains, as well as smoother and, denser morphology as observed by SEM. In agreement with previous studies, the coatings had a high transparency in the visual and near IR range; an optical band gap (E-04) between 4.6 and 5.2 eV and a refractive index between 1.9 and 2.1 was observed. The ternary coatings studied here were found to be hard with the HIPIMS coatings (combined average 22 +/- 3 GPa) being harder than their DCMS counterpart (combined average 17 +/- 1 GPa). A maximum hardness of 27 GPa was observed for the sample deposited with HIPIMS and a Si-content of 7 at.%.

Ämnesord

NATURVETENSKAP  -- Kemi -- Materialkemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Materials Chemistry (hsv//eng)

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