Elangovan Thangavel | Bharathiar University, Coimbatore, Tamilnadu, INDIA (original) (raw)

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Papers by Elangovan Thangavel

Journal of Nanoscience and Nanotechnology, 2009

Synthesis of nanocomposite thin films of CrN/Cu deposited on (100) Si and D-9 alloy substrates by... more Synthesis of nanocomposite thin films of CrN/Cu deposited on (100) Si and D-9 alloy substrates by pulsed magnetron sputtering as a function of copper content in the range 15.1-35.8 at.% is investigated. XRD analysis of the films deposited at 773 K with nitrogen flow rate of 10 sccm indicated that the films are nanorystalline and bi-phasic (fcc-CrN and fcc-Cu). Scanning electron microscopy showed a structureless morphology for CrN, while agglomerates were obtained for CrN/Cu nanocomposite thin films. Atomic force microscopy also confirmed the agglomeration of particles with increasing Cu content. The amount of copper content in the nanocomposite films had also shown a significant reduction in the crystallite size of CrN. The nano hardness measurements showed a peak hardness of 17 GPa for the films with copper content of 15.1 at.%. The hardness values were found to decrease significantly with Cu content > 31.1 at.%.

Application of biodegradable implants has received increasing attention for the treatment of bone... more Application of biodegradable implants has received increasing attention for the treatment of bone damage due to their low adverse effects. To achieve better biocompatibility and enhanced corrosion resistance of biodegradable implants with improved wear resistance, multifunctional coatings need to be developed.

Surface Engineering, 2012

Synthesis of nanocomposite thin films of CrN/Cu on (100) Si and titanium modified stainless steel... more Synthesis of nanocomposite thin films of CrN/Cu on (100) Si and titanium modified stainless steel (D-9 alloy) substrates by pulsed magnetron sputtering from a composite target of Cr-Cu using sputtering gas mixture of argon and nitrogen is investigated. X-ray diffraction analysis of the films deposited at 773 K and 10 sccm of nitrogen flowrate indicated that the films are nanocrystalline and biphasic (fcc CrN and fcc Cu). The films showed a peak hardness of y15 GPa and a Young's modulus of y200 GPa for those with a copper content of 15?1 at-%, and these values were found to decrease significantly with a Cu content of >18?4 at-%. The evaluation of the antibacterial activity as a function of copper content in the range of 15?1-38?5 at-% indicated excellent antibacterial properties for CrN/Cu films with the copper content of 18?4 at-%. The phase stability of CrN of the nanocomposite is also discussed in relation to pure CrN thin films.

Surface and Coatings Technology, 2014

The mechanical durability and stability of a-C:Ag nanocomposite coatings deposited on 316L stainl... more The mechanical durability and stability of a-C:Ag nanocomposite coatings deposited on 316L stainless steel substrates were investigated with respect to Ag content. The coatings were prepared using graphite and Ag targets. The coatings were characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and transmission electron microscopy (TEM). XPS and Raman spectroscopy confirmed the formation of sp 2 clusters in the a-C coating with 4.46 at.% Ag content. Surface roughness was found to be reduced by increasing the Ag content in a-C coatings as confirmed by AFM analysis. TEM analysis also showed the presence of nanostructured Ag in the a-C matrix. The tribological and corrosion properties of these coatings were also investigated. Hardness and Young's modulus were found to decrease with increase in Ag content. The experimental results revealed that the friction coefficient could be significantly reduced due to inclusion of Ag in the composite coating. In particular, the coating with an Ag content of 4.46 at.% showed the best tribological behavior. Inclusion of Ag also improved the corrosion resistance of the composite coating. It was concluded that Ag content in a-C:Ag nanocomposite coating has a significant effect on the tribological and corrosion properties of the coating. Experimental results revealed that optimum Ag content (4.46 at.%) in a-C:Ag nanocomposite coatings may be effectively utilized to protect 316L stainless steel substrates.

Journal of Nanoscience and Nanotechnology, 2009

Synthesis of nanocomposite thin films of CrN/Cu deposited on (100) Si and D-9 alloy substrates by... more Synthesis of nanocomposite thin films of CrN/Cu deposited on (100) Si and D-9 alloy substrates by pulsed magnetron sputtering as a function of copper content in the range 15.1-35.8 at.% is investigated. XRD analysis of the films deposited at 773 K with nitrogen flow rate of 10 sccm indicated that the films are nanorystalline and bi-phasic (fcc-CrN and fcc-Cu). Scanning electron microscopy showed a structureless morphology for CrN, while agglomerates were obtained for CrN/Cu nanocomposite thin films. Atomic force microscopy also confirmed the agglomeration of particles with increasing Cu content. The amount of copper content in the nanocomposite films had also shown a significant reduction in the crystallite size of CrN. The nano hardness measurements showed a peak hardness of 17 GPa for the films with copper content of 15.1 at.%. The hardness values were found to decrease significantly with Cu content > 31.1 at.%.

Journal of Alloys and Compounds, 2011

In the present work, the growth characteristics of tantalum nitride (TaN) thin films prepared on ... more In the present work, the growth characteristics of tantalum nitride (TaN) thin films prepared on (1 0 0) Si substrates by reactive pulsed DC magnetron sputtering are investigated. XRD analyses indicated the presence of ␣-Ta and ␤-Ta in the films deposited in pure argon atmosphere, while ␤-TaN and fcc-TaN phases appeared for 2 sccm of nitrogen, and cubic TaN for 5-25 sccm of nitrogen in the sputtering gas mixture of argon and nitrogen at a substrate temperature of 773 K. The TaN films obtained with increasing substrate temperature and pulse width showed a change in the texture from [1 1 1] to [2 0 0] orientation. Atomic force microscopy (AFM) results indicated that the average surface roughness was low for films deposited in pure argon than for the films deposited in a mixed Ar + N 2 atmosphere. Nanocrystalline phase of the deposited material was identified from the high-resolution transmission electron microscopy (HRTEM) images. X-ray photoelectron spectroscopy (XPS) core level spectra confirmed the formation of TaN phase. The high temperature X-ray diffraction analysis of the optimized TaN thin film was performed in the temperature range 298-1473 K. The lattice parameter of the TaN films was found to increase from 4.383 to 4.393Å on increasing the temperature from 298 to 823 K and it reduced to 4.345Å at 1473 K. The thermal expansion coefficient value was found to be negative for the TaN films.

Composites Science and Technology, 2014

The possibility of engineering the crystalline structure and tribological properties of poly(viny... more The possibility of engineering the crystalline structure and tribological properties of poly(vinylidene fluoride) (PVDF) thin films (300 nm) using functionalized graphene oxide (FGO) was evaluated. Samples with 0.0, 0.5, 1.0, and 2.0 wt% FGO in the feed were spin cast on Si-wafer, characterized by X-ray photoelectron (XPS), Fourier-transform infrared and Raman spectroscopies, atomic force and scanning electron microscopies, and tribological analyses. XPS and Raman studies were confirmed the incorporation of FGO into the PVDF matrix. PVDF predominantly contained the a-phase. FGO suppressed the growth of the a-phase and favored the formation of the ferroelectric b-and c-phases. The surface topography changed from featureless to spherulites with or without well-grown dendrites upon FGO incorporation. In case of tribological characteristics, when a 10 mN normal load was applied in a reciprocating motion, the bare Si-wafer, PVDF, and PVDF-FGO-2.0 showed substantial damage after 50, 125, and 50 cycles, respectively. PVDF-FGO-0.5 was very stable even after 120 cycles whereas PVDF-FGO-1.0 showed mild abrasion.

Applied Surface Science, 2013

Ti-Si-C-N nanocomposite coatings were synthesized by a filtered vacuum arc (FVA) technique. A met... more Ti-Si-C-N nanocomposite coatings were synthesized by a filtered vacuum arc (FVA) technique. A metal organic precursor, tetramethylsilane (TMS), was used as a source for silicon and carbon to deposit the Ti-Si-C-N nanocomposite coating with a Ti cathode source. The chemical and microstructural properties of the as-deposited coatings were systematically investigated using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Nanoindentation and scratch tests were carried out to evaluate the mechanical and adhesion properties of the coatings. From the XPS analysis, it was found that the Si content in the coating increased from 2 to 16 at.% as the TMS flow rate was increased from 5 to 20 sccm. The TEM analysis clearly demonstrated that the coatings were composed of crystalline TiCN along with amorphous Si 3 N 4 as a secondary phase. From the XRD results, it was found that the crystallite size of TiCN increased with increasing Si content. The microstructure and mechanical properties of the TiSiCN coatings prepared by this method exhibited strong dependencies on the silicon content. A maximum hardness of 49 GPa and a coefficient of friction of 0.17 were obtained for the film with a silicon content of 3 at.%.

Advanced Materials Research, 2010

Zr-N thin films were deposited on Si (100) substrate by reactive sputtering using a pulsed DC mag... more Zr-N thin films were deposited on Si (100) substrate by reactive sputtering using a pulsed DC magnetron sputtering technique. It was found that films deposited at 773 K and 1 sccm of nitrogen flow rate show a single phase with face centred cubic-ZrN. Raman analysis also confirmed the formation of ZrN phase in the films. The films deposited at nitrogen flow rate greater than 1 sccm show ZrN along with orthorhombic-Zr 3 N 4. The chemical bonding characteristics of the films were analyzed by X-ray photoelectron spectroscopy. High resolution transmission electron microscopy also gave evidence for fcc-ZrN and o-Zr 3 N 4 phase and revealed equiaxed grains in these films. In addition, hardness and Young's modulus of the films measured as a function of nitrogen flow rate is discussed qualitatively in relation to resistance to plastic deformation offered by these films.

Journal of Nanoscience and Nanotechnology, 2009

Synthesis of nanocomposite thin films of CrN/Cu deposited on (100) Si and D-9 alloy substrates by... more Synthesis of nanocomposite thin films of CrN/Cu deposited on (100) Si and D-9 alloy substrates by pulsed magnetron sputtering as a function of copper content in the range 15.1-35.8 at.% is investigated. XRD analysis of the films deposited at 773 K with nitrogen flow rate of 10 sccm indicated that the films are nanorystalline and bi-phasic (fcc-CrN and fcc-Cu). Scanning electron microscopy showed a structureless morphology for CrN, while agglomerates were obtained for CrN/Cu nanocomposite thin films. Atomic force microscopy also confirmed the agglomeration of particles with increasing Cu content. The amount of copper content in the nanocomposite films had also shown a significant reduction in the crystallite size of CrN. The nano hardness measurements showed a peak hardness of 17 GPa for the films with copper content of 15.1 at.%. The hardness values were found to decrease significantly with Cu content > 31.1 at.%.

Application of biodegradable implants has received increasing attention for the treatment of bone... more Application of biodegradable implants has received increasing attention for the treatment of bone damage due to their low adverse effects. To achieve better biocompatibility and enhanced corrosion resistance of biodegradable implants with improved wear resistance, multifunctional coatings need to be developed.

Surface Engineering, 2012

Synthesis of nanocomposite thin films of CrN/Cu on (100) Si and titanium modified stainless steel... more Synthesis of nanocomposite thin films of CrN/Cu on (100) Si and titanium modified stainless steel (D-9 alloy) substrates by pulsed magnetron sputtering from a composite target of Cr-Cu using sputtering gas mixture of argon and nitrogen is investigated. X-ray diffraction analysis of the films deposited at 773 K and 10 sccm of nitrogen flowrate indicated that the films are nanocrystalline and biphasic (fcc CrN and fcc Cu). The films showed a peak hardness of y15 GPa and a Young's modulus of y200 GPa for those with a copper content of 15?1 at-%, and these values were found to decrease significantly with a Cu content of >18?4 at-%. The evaluation of the antibacterial activity as a function of copper content in the range of 15?1-38?5 at-% indicated excellent antibacterial properties for CrN/Cu films with the copper content of 18?4 at-%. The phase stability of CrN of the nanocomposite is also discussed in relation to pure CrN thin films.

Surface and Coatings Technology, 2014

The mechanical durability and stability of a-C:Ag nanocomposite coatings deposited on 316L stainl... more The mechanical durability and stability of a-C:Ag nanocomposite coatings deposited on 316L stainless steel substrates were investigated with respect to Ag content. The coatings were prepared using graphite and Ag targets. The coatings were characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and transmission electron microscopy (TEM). XPS and Raman spectroscopy confirmed the formation of sp 2 clusters in the a-C coating with 4.46 at.% Ag content. Surface roughness was found to be reduced by increasing the Ag content in a-C coatings as confirmed by AFM analysis. TEM analysis also showed the presence of nanostructured Ag in the a-C matrix. The tribological and corrosion properties of these coatings were also investigated. Hardness and Young's modulus were found to decrease with increase in Ag content. The experimental results revealed that the friction coefficient could be significantly reduced due to inclusion of Ag in the composite coating. In particular, the coating with an Ag content of 4.46 at.% showed the best tribological behavior. Inclusion of Ag also improved the corrosion resistance of the composite coating. It was concluded that Ag content in a-C:Ag nanocomposite coating has a significant effect on the tribological and corrosion properties of the coating. Experimental results revealed that optimum Ag content (4.46 at.%) in a-C:Ag nanocomposite coatings may be effectively utilized to protect 316L stainless steel substrates.

Journal of Nanoscience and Nanotechnology, 2009

Synthesis of nanocomposite thin films of CrN/Cu deposited on (100) Si and D-9 alloy substrates by... more Synthesis of nanocomposite thin films of CrN/Cu deposited on (100) Si and D-9 alloy substrates by pulsed magnetron sputtering as a function of copper content in the range 15.1-35.8 at.% is investigated. XRD analysis of the films deposited at 773 K with nitrogen flow rate of 10 sccm indicated that the films are nanorystalline and bi-phasic (fcc-CrN and fcc-Cu). Scanning electron microscopy showed a structureless morphology for CrN, while agglomerates were obtained for CrN/Cu nanocomposite thin films. Atomic force microscopy also confirmed the agglomeration of particles with increasing Cu content. The amount of copper content in the nanocomposite films had also shown a significant reduction in the crystallite size of CrN. The nano hardness measurements showed a peak hardness of 17 GPa for the films with copper content of 15.1 at.%. The hardness values were found to decrease significantly with Cu content > 31.1 at.%.

Journal of Alloys and Compounds, 2011

In the present work, the growth characteristics of tantalum nitride (TaN) thin films prepared on ... more In the present work, the growth characteristics of tantalum nitride (TaN) thin films prepared on (1 0 0) Si substrates by reactive pulsed DC magnetron sputtering are investigated. XRD analyses indicated the presence of ␣-Ta and ␤-Ta in the films deposited in pure argon atmosphere, while ␤-TaN and fcc-TaN phases appeared for 2 sccm of nitrogen, and cubic TaN for 5-25 sccm of nitrogen in the sputtering gas mixture of argon and nitrogen at a substrate temperature of 773 K. The TaN films obtained with increasing substrate temperature and pulse width showed a change in the texture from [1 1 1] to [2 0 0] orientation. Atomic force microscopy (AFM) results indicated that the average surface roughness was low for films deposited in pure argon than for the films deposited in a mixed Ar + N 2 atmosphere. Nanocrystalline phase of the deposited material was identified from the high-resolution transmission electron microscopy (HRTEM) images. X-ray photoelectron spectroscopy (XPS) core level spectra confirmed the formation of TaN phase. The high temperature X-ray diffraction analysis of the optimized TaN thin film was performed in the temperature range 298-1473 K. The lattice parameter of the TaN films was found to increase from 4.383 to 4.393Å on increasing the temperature from 298 to 823 K and it reduced to 4.345Å at 1473 K. The thermal expansion coefficient value was found to be negative for the TaN films.

Composites Science and Technology, 2014

The possibility of engineering the crystalline structure and tribological properties of poly(viny... more The possibility of engineering the crystalline structure and tribological properties of poly(vinylidene fluoride) (PVDF) thin films (300 nm) using functionalized graphene oxide (FGO) was evaluated. Samples with 0.0, 0.5, 1.0, and 2.0 wt% FGO in the feed were spin cast on Si-wafer, characterized by X-ray photoelectron (XPS), Fourier-transform infrared and Raman spectroscopies, atomic force and scanning electron microscopies, and tribological analyses. XPS and Raman studies were confirmed the incorporation of FGO into the PVDF matrix. PVDF predominantly contained the a-phase. FGO suppressed the growth of the a-phase and favored the formation of the ferroelectric b-and c-phases. The surface topography changed from featureless to spherulites with or without well-grown dendrites upon FGO incorporation. In case of tribological characteristics, when a 10 mN normal load was applied in a reciprocating motion, the bare Si-wafer, PVDF, and PVDF-FGO-2.0 showed substantial damage after 50, 125, and 50 cycles, respectively. PVDF-FGO-0.5 was very stable even after 120 cycles whereas PVDF-FGO-1.0 showed mild abrasion.

Applied Surface Science, 2013

Ti-Si-C-N nanocomposite coatings were synthesized by a filtered vacuum arc (FVA) technique. A met... more Ti-Si-C-N nanocomposite coatings were synthesized by a filtered vacuum arc (FVA) technique. A metal organic precursor, tetramethylsilane (TMS), was used as a source for silicon and carbon to deposit the Ti-Si-C-N nanocomposite coating with a Ti cathode source. The chemical and microstructural properties of the as-deposited coatings were systematically investigated using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Nanoindentation and scratch tests were carried out to evaluate the mechanical and adhesion properties of the coatings. From the XPS analysis, it was found that the Si content in the coating increased from 2 to 16 at.% as the TMS flow rate was increased from 5 to 20 sccm. The TEM analysis clearly demonstrated that the coatings were composed of crystalline TiCN along with amorphous Si 3 N 4 as a secondary phase. From the XRD results, it was found that the crystallite size of TiCN increased with increasing Si content. The microstructure and mechanical properties of the TiSiCN coatings prepared by this method exhibited strong dependencies on the silicon content. A maximum hardness of 49 GPa and a coefficient of friction of 0.17 were obtained for the film with a silicon content of 3 at.%.

Advanced Materials Research, 2010

Zr-N thin films were deposited on Si (100) substrate by reactive sputtering using a pulsed DC mag... more Zr-N thin films were deposited on Si (100) substrate by reactive sputtering using a pulsed DC magnetron sputtering technique. It was found that films deposited at 773 K and 1 sccm of nitrogen flow rate show a single phase with face centred cubic-ZrN. Raman analysis also confirmed the formation of ZrN phase in the films. The films deposited at nitrogen flow rate greater than 1 sccm show ZrN along with orthorhombic-Zr 3 N 4. The chemical bonding characteristics of the films were analyzed by X-ray photoelectron spectroscopy. High resolution transmission electron microscopy also gave evidence for fcc-ZrN and o-Zr 3 N 4 phase and revealed equiaxed grains in these films. In addition, hardness and Young's modulus of the films measured as a function of nitrogen flow rate is discussed qualitatively in relation to resistance to plastic deformation offered by these films.