Changes in Structural, Morphological, and Corrosion Properties of CrN Thin Film Effected by Varying N₂ Pressure in the Sputtering Process

Abstract:

In this study, we investigate a facet of the fabrication process of chromium nitride (CrN) film intended as a protective coating for pineapple blades. CrN thin films were deposited on unpolished stainless steel substrates (AISI304) by DC reactive magnetron sputtering in Ar+N₂ gases. In principle, the proportion of nitrogen partial pressure to the total pressure in the sputtering process should have considerable effects on the CrN film’s chemical composition, its crystal structure, its hardness, and its corrosion resistance. We tested this supposition out by using several different nitrogen partial pressures in the sputtering process and observed the films deposited. The coatings were deposited at five different nitrogen partial pressures of 4.0x10^-4 mbar, 8.0x10^-4 mbar, 1.2x10^-3 mbar, 1.6x10^-3 mbar, and 2.0x10^-3. The deposition times were controlled to achieve 5-µm thick films in each deposition. The films were analyzed by several analytical methods, such as X-ray diffraction (XRD), scanning electron microscope, micro-hardness and potentiostat in pineapple juice. The XRD spectra of the films showed face-centered cubic structure with (200) preferred orientation, positively identifying them as Cr₂N and CrN thin films. The calculated d-spacing and lattice parameter of the CrN films increased with increasing nitrogen partial pressure; the ranges were 0.283–0.287 nm and 0.491-0.497 nm, respectively. The cross-section morphology of the CrN films reveals the columnar grain growth with a high density. The crystal structure and the grain texture correspond with the hardness property. The films corrosion potential, an indicator of their corrosion property, was varied from -0.14 to -0.05 volts with varying nitrogen pressure. The most corrosion resistant and the good hardness were the film fabricated at the nitrogen partial pressure of 1.2x10^-3 mbar.

• Periodical: Key Engineering Materials (Volume 659)
• Pages: 555-559
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.659.555
• Online since: August 2015
• Authors: Wichuda Wongtanasarasin, Rachsak Sakdanuphab, Kajpanya Suwansukho, Aparporn Sakulkalavek
• Keywords: Corrosion, CrN Thin Film, DC Reactive Magnetron Sputtering

References

[1] J. J Olaya, S.E. Rodil, S. Muhl, E. Sanchez, Comparative study of chromium nitride coatings deposited by unbalanced and balanced magnetron sputtering, Thin solid films 474 (2005) 119-126.

DOI: 10.1016/j.tsf.2004.08.067

[2] G. Wei, A. Rar, J.A. Barnard, Composition, structure, and nanomechanical properties of DC-sputtered CrNx (0≤x≤1) thin films, Thin solid films 398-399 (2001) 460-464.

DOI: 10.1016/s0040-6090(01)01388-8

[3] C. Keawhan ,P. Wongpanya, N. Witit-anun, P. Songsiriritthigul, Corrosion behavior of AISI 4140 steel surface coated by physical vapor deposition, J. Metals. Materials and Minerals. 22 (2012) 69 – 76.

[4] C. Thawontira, S. Chaikhun, S. Tungkasamit, Research and development of cromium nitride thin films on cutting tools for agricultural products, Institute of research and development Suranaree University of Technology, Thailand, (2012).

[5] A. Ruden, E. Restrepo-Parra, A.U. Paladines, F. Sequeda, Corrosion resistance of CrN thin films produced by dc magnetron sputtering, Applied Surface Science 270 (2013) 150– 156.

DOI: 10.1016/j.apsusc.2012.12.148

[6] Kyung H. NamU, Min J. Jung, Jeon G. Han, A study on the high rate deposition of CrNx films with controlled microstructure by magnetron sputtering, Surface and Coatings Technology 131 (2000) 222-227.

DOI: 10.1016/s0257-8972(00)00813-6