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Use of nano‐materials as lubricant additives is gaining tremendous importance due to their capabilities in enhancing the tribo‐performance. The nano‐particles of various elements and compounds are efficiently blended in mineral base oils enhancing their physico‐chemical as well as tribological properties. However, in recent times due to the environmental concerns, focus is being shifted toward bio based lubricants. Bio lubricants are obtained from plant oil by various chemical modification techniques. They are environment friendly, biodegradable and have better lubricating properties than the mineral oil based counterparts. The major challenge however for these lubricants is the selection of appropriate additives. The commercial additives developed for mineral base oils are generally toxic and not suitable for the Biolubricants. In this context, the present paper attempts to investigate the efficacy of Cu nano‐particles as additive for Biolubricants. The non‐edible karanja oil has been chemically modified to karanja ester and used as biolubricant. The functionalized Cu nano‐particles have been blended in various concentrations in biolubricant and the tribological performance investigated using four ball tribo‐tester. In order to ascertain the efficacy of Cu nano‐particles as additives, the tribo‐performance of Cu nano‐particle blended biolubricant has been compared with that of Zinc dialkyl dithio phosphate (ZDDP) blended biolubricant in equal concentrations. ZDDP is a conventional commercially available multi‐purpose additive that enhances the tribo‐performance of lubricating oils. The comparative study of experimental results showed that ZDDP helps in enhancing the anti‐wear performance of bio‐lubricant while the Cu nano‐particles aided in enhancement of anti‐friction behavior of biolubricant.

The present paper introduces new type of 2D structured nano‐sheets as additives for lubricating oils. The 2D structured nano‐sheets of graphitic‐C3N4 (g‐C3N4) have been grafted with Octadecylamine to be used as additives. The nano‐fluids have been synthesized by blending amine grafted g‐C3N4 in lubricating oil in different weight percentage. A stable dispersion of g‐C3N4 in the base fluids has been achieved. The dispersion stability of nano‐fluids has been studied using UV‐visible spectrometer. The grafted g‐C3N4 nano‐sheets were characterized by analytical techniques like FT‐IR, TGA, TEM and EDX. The tribological properties of grafted g‐C3N4 nano‐fluids have been evaluated using 4 ball tribo‐tester using standard ASTM D: 4172B procedure. The comparative assessment of tribo‐performance reveals that amine grafted g‐C3N4 nano‐fluid significantly improve the anti‐friction and anti‐wear property. For a given concentration the g‐C3N4 nano‐fluids reduces friction and wear by 32 % and 17 % respectively as compared base fluid.

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This paper reports the influence of operating parameters on the tribological performance of Cu nanofluids. The nanofluids have been prepared by blending oleic acid-functionalized Cu nanoparticles in mineral base oil and commercial multigrade lubricant. The functionalized Cu nanoparticles have been characterized by analytical techniques to ascertain chemical composition and structure of particles. The UV results indicate stable dispersion of nanofluids. The experiments have been performed to investigate the influence of load, speed, and temperature on the tribo-performance behavior of nanofluids. The tribological performance reveals that the Cu nanofluids help in reducing friction and wear more significantly within the contact as compared to the base fluid under studied operating conditions.