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Improvement of hardness and corrosion resistance of SS-420 by Cr+TiN coatings

Novinrooz A. J., Afshari N., Seyedi H.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 23, nr 1

43-46

EN

Purpose: Double layer Cr+TiN thin films were coated on SS-420 substratum to achieve a corrosion resistive system. Design/methodology/approach: Ion coating technique was employed for deposition of TiN on stainless steel and subsequently, chromium was coated resulting Cr+TiN composite. Findings: : In this work we have purposed to improve the natural defect of hard coating material, TiN against corrosion phenomena. This task was fulfilled by formation of a double layer Cr+TiN, which was characterized by glow discharge optical emission spectroscopy (GDOS) for compositional analysis of content elements. X-ray diffraction (XRD) technique was utilized to investigate films crystalline structure. It was revealed that the composite with (111) plane of reflection possess very good corrosion resistive behavior. Scanning electron microscopy (SEM) image showed a double layer configuration. Research limitations/implications: As the study was carried out on limited surfaces, it is necessary to endeavour further work on larger area. Practical implications: As the galvanic corrosion is a common problem in thin film technology due to its pinholes and small grains, therefore, any attempt to overcome this problem is encouraged. Originality/value: : Due to limited work and data available on literature about the corrosion resistive thin layers, it may regard this work as a valuable and remarkable approach.

2

Microhardness study of Ti(C, N) films deposited on S-316 by the Hallow Cathode Discharge Gun

Novinrooz A. J., Seyedi H., Larijani M. M.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 14, nr 1-2

59--63

EN

Purpose: The micro hardness properties of Titanium Carbonitride composite coated on SS-316 substrates were studied to achieve a desired harden surfaces. Design/methodology/approach: Hollow Cathode Discharge gun (HCD–gun) was employed for deposition of the Ti(C, N) on SS-316. The evaporated and ionized metal (Ti) was coated as an under layer with 0.5 ampere beam current and 100 volt bias voltage. The reactant nitrogen and methane gasses were fed through inlet in to the chamber containing Ti element to form Ti (C, N) matrix with an optimized ratio. Findings: In this work, Glow Discharge Optical emission Spectroscopy (GDOS) used for composition alanalysis of the content elements. On the bases of this operation it was revealed the existence of Ti, C, N elements, X-ray diffraction (XRD) technique was utilized to investigate films crystalline structure. The investigation showed that samples with different stoichiometry have a fcc structure with (111) plan of reflection. The atomic ratio of carbon and nitrogen were measured using energy dispersive X-ray (EDX) analysis. The optimized value was funned to be TiC0.87 N0.13. The atomic force microscopy (AFM) and scanning electronmicroscopy (SEM) were employed to study the films microstructure. A hardness of 3250 HV was obtained in the carbon content C/C+ N atomic ratio of 9 to 1 using a Vickers microhardness tester. Research limitations/implications: As the study was carried out on a limited surfaces, we shall endeavor further attempt on large area deposition. Practical implications: The tools coated in titanium accompanied by nitride and carbide has shown significant improvement. Good compatibility of Ti (C, N) compound makes these composite suitable in various technical and industrial applications. Originality/value: It may be remarked that, the hardness obtained in this work is very encouraging and therefore, it is convenient to regard this as a privileged step taken in tool manufacturing aspect.

3

Effect of nitrogen flow rate on properties of CrN films Prepared by HCD-gun

Novinrooz A. J., Seyedi H.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 17, nr 1-2

189--192

EN

Purpose: The effect of reactant nitrogen gas flow rate on the tribological properties of CrN thin films was studied. Design/methodology/approach: Hollow Cathode Discharge gun (HCD-gun) was employed for the coating of CrN films on the glass and SS-316 sub strum. The reactant nitrogen with different flow was fed in to the vacuum chamber of 3x10-3 Pa pressure to form Cr N composite under experimental condition. Findings: The crystalline phase and micro structural studies of the specimens were carried out by XRD and SEM respectively. It was found that the preferred orientation for CrN films was (200) and that for Cr2N was (111). The micro hardness measurement fulfilled by Vickers test, and the hardness value obtained was 2100kgm-2. The glow discharge optical emission spectroscopy (GDOES) was used for compositional analysis of the content elements. The wear resistance test was performed under specific condition. Research limitations/implications: We have completed our discussion by commenting the results on small deposition area, and therefore, we endeavor further attempt on large area coating. Practical implications: The Cr-N composite due to higher hardness, wear resistance and anticorrosion characteristics is widely used in cutting tools, aerospace and industrial fields. Originality/value: It may be remarked that the hardness and wear resistance values obtained in this work is very encouraging and therefore makes thin composite suitable in various technical applications.