Browsing by Author "Siva Shanmugam, N.S."

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Influence of Solid Lubricants on Microstructure and Tribological Performance of Nickel-Based Composite Coatings
(Springer, 2022) Gudala, S.; Ramesh, M.R.; Siva Shanmugam, N.S.
The present study investigates the microstructure and high-temperature tribological studies of solid lubricant encapsulated nickel alloy coatings developed by tungsten inert gas (TIG) cladding technique. The TIG current values of 90Â A, 95Â A, and 100Â A were considered as process parameters. The microstructure of the coatings (coating A: NiCrSiB/WC/Ag/hBN, coating B: NiCrSiB/WC/MoS2/hBN) was characterized using the scanning electron microscopy, X-ray diffraction, X-ray energy dispersive spectroscopy and EBSD (electron backscatter diffraction) analysis. The dry sliding wear studies were conducted using a pin on disc apparatus, and the microhardness of the coating was assessed using Vickerâ€™s indentation technique. The results show that coating A exhibited high hardness and excellent tribological properties than coating B. In particular, coating A presents the high average microhardness (950Â HV), low coefficient of friction (0.34), and wear rate (2.96 Ã— 1âˆ’3Â mm3/N-m). Additionally, coating A showed three-fold higher hardness and a 2.43 times lower wear rate than the titanium substrate. The lubricant phases (Ag, BN, Mo2S3) and oxide phases (TiO, Ag2O, Ni (TiO3)) formed in both coatings were adequate to reduce the material loss. Â© 2022, ASM International.
Influence of Solid Lubricants on Microstructure and Tribological Performance of Nickel-Based Composite Coatings
(Springer, 2022) Gudala, S.; Ramesh, M.R.; Siva Shanmugam, N.S.
The present study investigates the microstructure and high-temperature tribological studies of solid lubricant encapsulated nickel alloy coatings developed by tungsten inert gas (TIG) cladding technique. The TIG current values of 90 A, 95 A, and 100 A were considered as process parameters. The microstructure of the coatings (coating A: NiCrSiB/WC/Ag/hBN, coating B: NiCrSiB/WC/MoS2/hBN) was characterized using the scanning electron microscopy, X-ray diffraction, X-ray energy dispersive spectroscopy and EBSD (electron backscatter diffraction) analysis. The dry sliding wear studies were conducted using a pin on disc apparatus, and the microhardness of the coating was assessed using Vicker’s indentation technique. The results show that coating A exhibited high hardness and excellent tribological properties than coating B. In particular, coating A presents the high average microhardness (950 HV), low coefficient of friction (0.34), and wear rate (2.96 × 1−3 mm3/N-m). Additionally, coating A showed three-fold higher hardness and a 2.43 times lower wear rate than the titanium substrate. The lubricant phases (Ag, BN, Mo2S3) and oxide phases (TiO, Ag2O, Ni (TiO3)) formed in both coatings were adequate to reduce the material loss. © 2022, ASM International.
MICROSTRUCTURE AND TRIBOLOGICAL PERFORMANCE OF SELF-LUBRICATE CLADDING PRODUCED BY TUNGSTEN INERT GAS AND MICROWAVE HYBRID HEATING TECHNIQUES
(World Scientific, 2022) Gudala, S.; Ramesh, M.R.; Siva Shanmugam, N.S.; Srinath, M.S.
The wear reduction of moving components is highly desirable because wear limits their reliability and service life, mainly at elevated temperatures. This study produced thick clads of NiCrSiB/WC/MoS2/BaF2 by tungsten inert gas (TIG) and microwave hybrid heating (MHH) cladding techniques, which were compared for microstructural and high-temperature tribological properties. The clad samples were subjected to sliding contact using a pin on disc tribometer at 200°C, 400°C, 600°C under 20 and 40N load. The worn surface was analyzed using FESEM, XRD and three-dimensional (3D) profilometer. The experimental results revealed a significant effect of the TIG current and MHH exposure time on the microhardness value, which predominantly depends on the morphological characteristics. The average hardness of TIG clads was found to be 1.2 times higher than the MHH clad. Because of the MoS2 and BaF2 encapsulation, the continuous lubricant layer formation compensated for improved wear resistance with good reliability and longer service life. This work provides significant insights into the wear behavior of TIG and MHH clads at elevated temperatures and the prospective applications in turbines, where inadequate wear resistance of titanium alloy is the major concern for its use. © 2022 World Scientific Publishing Company.
Studies on crack propogation in plasma arc welded Ti-6Al-4V joint during erichsen cupping test
(Blue Eyes Intelligence Engineering and Sciences Publication, 2019) Veeman, V.; Patil, R.; Sriram, G.; Siva Shanmugam, N.S.
Formability is one of the important parameter which describes the quality of the sheet metal. It is the ability of sheet metal to undergo plastic deformation without being damaged. There are two types of formability tests. One is a simple test which includes tensile, bulge and hardness test, another is simulative test like Erichsen cupping test, limit done height test, swift cup test. In this paper, numerical and experiemntatal investigations of formability of Ti-6Al-4V sheet are presented. Plasm arc welding experiment is conducted on thin Ti-6Al-4V sheet and Erichsen cupping test is uysed as the test method to determine the Erichsen cupping parameters. Tests have been conducted on plasma arc welded thin Ti-6Al-4V joint sheet as well as on the parent metal. Erichsen cupping index (IE) and acture load are determined during experimentation. Finite element analysis is done using commerical ABAQUS code. The simulation results are compared with experimental results. Based on the results, it is observed that the formability of welded Ti-6Al-4V is more than the base metal and the predicted Erichsen cupping index (IE), fracture load are good in agreeembnt with the experimental results. © BEIESP.