Percorrer por autor "Kumar, Ch. Sateesh"
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- Performance evaluation of TiAlSiN and TiSiN/TiSiVN coatings during high-speed dry turning of AISI 316 L considering the role of vanadium-based tribo-oxidesPublication . Fernandes, Filipe; Kumar, Ch. Sateesh; Lacalle, Luis Norberto López de; Cavaleiro, Albano; Cavaleiro, Diogo; Kalin, Mitjan; Prajapati, RamanandThis study investigates the tribo-mechanical performance of uncoated, TiAlSiN-coated, and TiSiN/TiSiVN multilayer-coated Al2O3/SiC ceramic tools during dry turning of AISI 316 L austenitic steel across three successive passes at varying cutting speeds. Key machining outputs, including cutting forces, surface roughness, cutting temperature, and tool wear (flank and crater), were analyzed with a focus on oxide formation and selflubricating mechanisms. The TiSiN/TiSiVN-coated tool exhibited the most favorable performance, showing only ~15 % increase in cutting force across passes, ~9 % improvement in flank wear resistance compared to TiAlSiN, and ~ 17 % lower wear progression relative to the uncoated tool at 350 m/min. Surface roughness and cutting temperature trends further confirmed the coating’s superiority, attributed to the formation of V₂O₅ tribo-oxides, which reduce friction and thermal degradation. EDS and SEM analyses validated the wear protection mechanisms, highlighting the adaptive role of vanadium-based layers in mitigating adhesion and thermal fatigue. The results establish TiSiN/TiSiVN as a promising candidate for high-speed dry machining due to its superior mechanical-chemical synergy and wear resistance.
- Tribological performance of different alloyed DLC and AlTiSiN coatings when sliding against Inconel 718 alloy for demanding applicationsPublication . Fernandes, Filipe; Pérez-Salinas, Cristian; Evaristo, Manuel; Cavaleiro, Albano; Kumar, Ch. Sateesh; Lacalle, L. Norberto López; Rios, P.Machining Ni alloys such as Inconel 718 is challenging due to its good mechanical properties, low thermal conductivity and low elastic modulus, which causes high cutting temperatures at the chip-tool interface. The use of self-lubricating coatings, such as DLCs coatings has potential to improve significantly the machinability of Ni alloys. This research work aims to explore how different DLC, DLC-Si, DLC-W coatings behave tribologically when sliding against Inconel 718. The results will be compared with an industrial AlTiSiN coating used to protect the cutting tools. The morphology, mechanical properties and chemical composition of the coatings were analysed. To evaluate the tribological behaviour alternative sliding tests were performed under different conditions (room temperature – RT and 200 °C in dry condition and at RT with lubrication, using CUT-MAX S 50259-1 oil. The DLC coatings showed remarkable self-lubricating efficiency, with low coefficients of friction even in dry conditions, demonstrating that their self-lubricating capability is effective without the need for external lubricants. However, at a temperature of 200 °C, a significant increase in wear rate was observed for all DLC coatings, being 3 to 4 times higher as compared to that at room temperature. This is mainly caused by the conversion of sp3 to sp2 bonds coating oxidation. On the other hand, AlTiSiN demonstrated consistent specific wear rate, despite of the unfavourable circumstances, highlighting its suitability to use in extreme environments. These results show the limitations in film performance and underline the importance of balancing the strength of the coating with its impact on the opposing surface. Furthermore, it highlights the need to improve the thermal stability of DLC coatings for application in high temperature environments and dry conditions.