Deposition and characterization of CrN/Si3N4 and CrAlN/Si3N4 nanocomposite coatings prepared using reactive DC unbalanced magnetron sputtering

Barshilia, Harish C and Deepthi, B and Rajam, KS (2007) Deposition and characterization of CrN/Si3N4 and CrAlN/Si3N4 nanocomposite coatings prepared using reactive DC unbalanced magnetron sputtering. Surface and Coatings Technology, 201 (24). pp. 9468-9475. ISSN 0257-8972

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Abstract

Nanocomposite coatings of CrN/Si3N4 and CrAlN/Si3N4 with varying silicon contents were synthesized using a reactive direct current (DC)unbalanced magnetron sputtering system. The Cr and CrAl targets were sputtered using a DC power supply and the Si target was sputtered using an asymmetric bipolar-pulsed DC power supply, in Ar+N2 plasma. The coatings were approximately 1.5 μm thick and were characterized using X-ray diffraction (XRD), nanoindentation, X-ray photoelectron spectroscopy and atomic force microscopy. Both the CrN/Si3N4 and CrAlN/Si3N4 nanocomposite coatings exhibited cubic B1 NaCl structure in the XRD data, at low silicon contents (b9 at.%). A maximum hardness and elastic modulus of 29 and 305 GPa, respectively were obtained from the nanoindentation data for CrN/Si3N4 nanocomposite coatings, at a silicon content of 7.5 at.%. (cf., 24 and 285 GPa, respectively for CrN). The hardness and elastic modulus decreased significantly with further increase in silicon content. CrAlN/Si3N4 nanocomposite coatings exhibited a hardness and elastic modulus of 32 and 305 GPa, respectively at a silicon content of 7.5 at.% (cf., 31 and 298 GPa, respectively for CrAlN). The thermal stability of the coatings was studied by heating the coatings in air for 30 min in the temperature range of 400–900 °C. The microstructural changes as a result of heating were studied using micro-Raman spectroscopy. The Raman data of the heat-treated coatings in air indicated that CrN/Si3N4 and CrAlN/Si3N4 nanocomposite coatings, with a silicon content of approximately 7.5 at.% were thermally stable up to 700 and 900 °C, respectively.

Item Type: Article
Uncontrolled Keywords: CrN/Si3N4 and CrAlN/Si3N4 nanocomposite coatings; Unbalanced magnetron sputtering; Structural and mechanical properties; Thermal stability
Subjects: CHEMISTRY AND MATERIALS > Composite Materials
PHYSICS > Solid-State Physics
Depositing User: Mr N Selvakumar
Date Deposited: 05 Aug 2011 05:34
Last Modified: 19 Sep 2011 06:13
URI: http://nal-ir.nal.res.in/id/eprint/9739

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