Field of Invention:
[001] The present invention relates to graphene nanotechnology and its application in mechanical lubrication and uniform thermal heat dissipation in lubricant and more particularly related to preparation of graphene nano-composite/derivatives composition for use in high performance engines. The present invention relates generally to the field of lubricant or grease. In particular, the invention provides a lubricant or grease modified by nano graphene composite, also known as graphene nanosheets. The Graphene nanocomposite includes pristine graphene that is substantially free from oxygen, as well as the oxidized graphene and crosslinked graphene also known as graphene nanocomposite.
Background of the Invention:
[002] With high speed urbanization and industrialization, serve extreme need for more efficient lubricant with graphene based nanoparticles also known as nano lubricants to reduce friction and wear processes along with heat modulation of the complete system.
[003] Lubricants and greases of various types are used in equipment and in manufacturing processes to reduce friction and wear and, in many situations, remove waste heat. Although some lubricants are water-based, most of the lubricants are oil-based, containing, for instance, mineral oil, poly (alpha olefin) oil, ester synthetic oil, ethylene oxide/propylene oxide synthetic oil, polyalkylene glycol synthetic oil, and silicone oil.
[004] The main technical requirements for lubricants are that they must be able to: (a) keep surfaces of working parts separate under all loads, temperatures and speeds, thus minimizing friction and wear; (b) act as a cooling fluid removing the heat produced by friction or from external

sources; (c) remain adequately stable in order to guarantee constant behaviour over the forecasted useful life; (d) protect surfaces from the attack of aggressive products formed during operation; and (e) fulfil detersive and dispersive functions in order to remove residue and debris that may form during operation. The main properties of lubricants, which are usually indicated in the technical characteristics of the product, are viscosity, viscosity index, pour point, and flash point. However, more and more machinery operation environments demand an effective heat management strategy, typically requiring the use of a lubricant with a high thermal conductivity. The thermal conductivity values of the commonly used lubricating oils (without an additive) are typically in the range of 0.1 to 0.17 W/m-K at room temperature and thus they are not good heat transfer agents.
Object of the Invention:
[005] The principal objective of the present invention is to synthesize graphene nano-composite/derivative lubricant composition with nano graphene sheets effective to provide an increase in anti-wear properties of the lubricant composition.
[006] Yet another object of the present invention is to provide graphene nano-composite/derivative lubricant composition that requires no extra post processing for application.
[007] Yet another object of the present invention is to provide graphene nano-composite/derivative lubricant composition that effectively dissipates heat from the system.
[008] Yet another object of the present invention is to provide graphene nano-composite/derivative lubricant composition that shows excellent shelf life.
[009] Yet another object of the present invention is to provide graphene nano-composite/derivative that gives uniform nano dispersion once used in lubricant composition master batch for application.

[010] Yet another object of the present invention is to provide graphene nano-composite/derivative lubricant composition that provides the improved oil viscosity index for low to elevated temperatures.
[Oil] Yet another object of the present invention is to provide graphene nano-composite/derivative lubricant composition that forms nano lubricating coating over the mechanical surfaces.
[012] Yet another object of the present invention is to provide graphene nano-composite/derivative lubricant composition that improves solubility in said oil and which exhibit superior compatibility with other oil included additives.
[013] Yet another object of the present invention is to provide graphene nano-composite/derivative lubricant composition that impart superior colloidal stability to the lubricating oil compositions while maintaining an unusually high degree of solubility within said lubricating oil compositions.
[014] Yet another object of the present invention is to provide graphene nano-composite/derivative lubricant composition that provides the improved thermal stability to the lubricant at elevated temperatures.
[015] Yet another object of the present invention is to provide graphene nano-composite/derivative lubricant composition that provides the improved heat transfer rate to the lubricant.
[016] Yet another object of the present invention is to provide a preparation method for graphene nano-composite/derivative lubricant composition.
[017] Yet another object of the present invention is to provide a preparation method for graphene nano-composite/derivative lubricant composition, where the preparation method includes high shear mixing, vacuum mixing, mechanical milling and a combination of high shear mechanical milling methods.
[018] Yet another object of the present invention is to provide a graphene nano-composite/derivative lubricant composition, where the oxygen content in graphene nano-composite/derivative is less than 5%.

Significance of the Invention:
[019] The main significance of the present invention is to provide graphene nano-composite/derivative lubricant composition with nano graphene sheets effective to provide an increase in anti-wear properties of multiple lubricant forms such as Oil, Grease, Penetrating Lubricants, and Dry Lubricants.
[020] Another significance of the present invention is to provide graphene nano-composite/derivative lubricant composition that enhances thermal conductivity of the base lubricant by 10-40%.
[021] Yet another significance of the present invention is to provide graphene nano-composite/derivative lubricant composition having same shelf life as that of a base lubricant.
[022] Yet another significance of the present invention is to provide a graphene nano-composite/derivative lubricant composition that is thermally stable at higher temperature in the range of 400°C to 600°C.
[023] Yet another significance of the present invention is to provide graphene nano-composite/derivative lubricant composition that reduces the coefficient of friction up to 10-
O O t5 •
Description of the Invention:
[024] The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive

inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such a process or method. Similarly, one or more systems or sub-systems or elements or structures or components preceded by "comprises... a'' does not, without more constraints, preclude the existence of other systems, sub-systems, elements, structures, components, additional systems, additional sub-systems, additional elements, additional structures or additional components. Appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but not necessarily do, all refer to the same embodiment.
[025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention belongs. The system, methods, and examples provided herein are only illustrative and not intended to be limiting.
[026] It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present invention. Moreover, all statements herein reciting principles, aspects, and embodiments of the present invention, as well as specific examples, are intended to encompass equivalents thereof.
[027] According to one embodiment of the present invention, the graphene nano-composite/derivative lubricant composition with graphene nano graphene sheets which reduced the anti-wear properties to the moving mechanical machinery of high-performance machine by formation of nano coating over the mechanical parts it can be used in multiple form such as Oil, Grease, Penetrating Lubricants, and Dry Lubricants.
[028] According to one embodiment of the present invention, the graphene nano-composite/derivative lubricant composition that requires no further post processing for application. Showed easy compatibility with all types of synthetic and non-

synthetic oil for which the base material is selected in accordance to the masterbatch. [029] According to one embodiment of the present invention, the graphene nano-composite/derivative for lubricant composition is thermally stable at higher temperature in the range of 400C- to 600C. [030] According to one embodiment of the present invention, the graphene nano-composite/derivative for lubricant composition has excellent thermal conductivity is more than 500 W m-1 K-1. [031] According to one embodiment of the present invention, the graphene nano-composite/derivative lubricant composition improves the thermal conductivity of the base lubricants by 10-40%. [032] According to one embodiment of the present invention, the graphene nano-composite/derivative lubricant composition that has the same shelf life that is of base lubricant. [033] According to one embodiment of the present invention, graphene nano-composite/derivative for lubricant composition forms nano coating over the moving mechanical parts and fills the crevices on the surface. [034] According to one embodiment of the present invention, graphene nano-composite/derivative for lubricant composition reduced the coefficient of friction upto 10-35%. [035] According to one embodiment of the present invention, the steps involved in the synthesis of graphene oxide by modified Hummers method. The steps are broadly divided under three major chemical processes: 1) Chemical Oxidation 2) Purification 3) Extraction and Segregation 4) Functionalization. [036] According to one embodiment of the present invention, the thermal conductivity of thermally exfoliated graphene materials is enhanced due to removal of oxygen and amorphous carbon.

[037] According to one embodiment of the present invention, the graphene is functionalized with fatty acids to get stable dispersion of graphene in lubricant, where fatty acids can be but not limited to unsaturated fatty acid such as, Elaidic acid, Vaccenic acid, Sapienic acid, Oleic acid, Linoleic acid, etc.
[038] The invention will be more specifically illustrated by the following Example.
Example: Synthesis of Graphene Nanocomposite based additive for lubricants using 5gm graphite flakes
Synthesis of Graphene Oxide
[039] Initially graphene oxide is synthesized using 2gms graphite flakes by modified Hummers method. H2S04 and NaN03 are added in a ratio of 50:1 by volume to the graphite flakes. KMn04 is then added slowly to the above composition slowly while stirring continuously for four days to allow the oxidation of graphite. The completion of oxidation is confirmed by the color change of the solution from dark green to purplish brown. 10 ml H2O2 is added dropwise to the above composition till the sample color changes to milky white and subsequently to yellow, indicating high oxidation level of graphite. 500 ml of Lukewarm water is then added slowly and the sample is left for 12h to settle. When the layers are separated, the upper layer is decanted and 10% HC1 (100 ml) is added to the lower sedimented layer which is again kept for settling for 6 hours. The upper layer is again decanted to remove the acid. 500 ml De ionized water is mixed with the settled layer and left for settling for 6 hours. This process is repeated 2-3 times to decrease the acid content and the time for settling depends on the precursor graphite flakes. The decanted layer is then centrifuged at 12000 rpm for 20 minutes to remove the remaining acid. 100 ml De ionised water is added to the sediment. 1M NaOH solution is added to the

sediment for neutralization till the pH reaches 6.5 while stirring continuously and vigorously. The above composition is centrifuged at 14000 rpm for 30 minutes. The supernatant is discarded and water is added for further centrifugation. The process is repeated 4 times to remove the sodium salts. The washed pellets are dispersed in acetone water solution (30%v/v). The above solution is sonicated at 600 W for 2h. The sonicated solution is centrifuged at 8000 rpm for 12 minutes. The pellet is collected and dried at 55°C (in this step inferior quality of Graphene Oxide is obtained). To obtain superior quality Graphene Oxide, the supernatant is carefully collected and concentrated at 65°C under constant stirring. Further the pellets obtained are kept in a rotary evaporator and finally dried in an oven at 55°C
Synthesis of nitrogen doped Graphene:
[040] 2000 mL of 1 mg/ml Graphene Oxide water suspension is dried at 100°C to remove excess water. The resultant black solid Graphene Oxide (GO) is heat-treated in a ceramic quartz boat placed in a tube furnace in nitrogen atmosphere at a flow rate of 800 mL min-1. The temperature of the furnace is set at 800°C for duration of 2h. Temperature ramp rate of furnace is 10°C min-1. After the reaction time, the furnace is allowed to cool to room temperature and thermally reduced nitrogen doped graphene is collected.
Fatty acid functionalized:
[041] 0.5 gram of thermally reduced nitrogen doped graphene powder and 20 ml Oleic acid were placed in Teflon lined autoclave. The autoclave was heated at 240 °C for 5 h with the ramp rate of 10°C min-1. The unreacted oleic acid was removed using filtration. The product was washed from the reaction vessel using deionized water and methanol.The reaction mixture was directly filtered by suction filtration on the nylon

membrane and repeatedly washed with deionized water and methanol.
Amine functionalization of thermally reduced nitrogen doped oleic acid functionalized graphene:
[042] Thermally reduced nitrogen doped oleic acid functionalized graphene 0.5 gm is added to 30 ml ethylene glycol and bath sonicated for 1 hr at room temperature. The above solution along with 5 ml ammonia solution is transferred to Teflon lined autoclave and subjected to solvothermal reaction for 150°C for 12 h. After reaction, the vessel is allowed to cool down and the precipitate is separated by filtration and washed with DI water. The filtrate is dried at 80°C for overnight.
Synthesis of graphene nano-composite/derivative lubricant composition:
[043] 1000 mg amine-oleic acid co-functionalized thermally reduced nitrogen doped graphene powder is kept in vacuum oven at 120°C for 6 hrs to remove all the excess volatile impurities. The amine-oleic acid co-functionalized thermally reduced nitrogen doped graphene powder is added to the 1000 ml base 10W40 automobile lubricant oil in concentration of 0.1 wt%. The above mixture is then mechanically agitated at temperature from the range of 15°C - 2 6°C for 1 h. After that the above mixture is ultrasonically agitated at 600-1500W for 2 hrs at room temperature. The oil composition is mechanically stirred at 300-3000 RPM for 12 hrs to get graphene nano-composite/derivative lubricant composition.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific

embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments.
[044] It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope.

We claim
1. The process for the synthesis of Graphene Nanocomposite
based additive for lubricants comprises following steps:
i) Taking graphite flakes in the container; ii) synthesis of graphene oxide by modified hummers method; iii)doping of the graphene oxide with nitrogen element; iv) functionalization of nitrogen doped graphene with
unsaturated fatty acids; v) functionalization of the thermally reduced nitrogen
doped fatty acid functionalized graphene with amino
group; vi) synthesis of graphene Nano composite based additive for
lubricant;
2. The process for the synthesis of graphene nano composite
based additive for lubricant as claimed in claim 1 wherein
doping of the graphene oxide with nitrogen element
comprises following steps:
i) drying of Graphene Oxide water suspension at 100°C to remove excess water and obtaining the black solid Graphene Oxide (GO).
ii) Heating the graphene oxide in a ceramic quartz boat placed in a tube furnace in nitrogen atmosphere at a flow rate of 800 mL min-1 at 800°C for duration of 2h. Temperature ramp rate of furnace is 10°C min-1 iii) Cooling the furnace to room temperature;
iv) Obtaining the thermally reduced nitrogen doped graphene.
3. The process for the synthesis of graphene nano composite based additive for lubricant as claimed in claim 1

wherein functionalization of nitrogen doped graphene with
fatty acids comprises following steps:
i) autoclaving the thermally reduced nitrogen doped
graphene powder and unsaturated fatty acid in Teflon
lined autoclave at 240 °C for 5 h with the ramp rate
of 10°C min"1. ii) Removing the unreacted fatty acid using filtration. iii) Washing the resulatant product from the reaction
vessel using deionized water and methanol. iv) Filteration of the reaction mixture on the nylon
membrane followed by repeated washing with deionized
water and methanol
4. The process for the synthesis of graphene nano composite
based additive for lubricant as claimed in claim 1
wherein thermally reduced nitrogen doped fatty acid
functionalized graphene is functionalized with amino
group comprises following steps:
i) Adding ethylene glycol to thermally reduced nitrogen doped fatty acid functionalized graphene bath sonicated for 1 hr at room temperature.
ii) Transferring the above solution along with 5 ml ammonia solution to Teflon lined autoclave and subjected to solvo thermal reaction for 150°C for 12 h.
iii) Cooling down the vessel and separation of the precipitate by filtration followed by washing with De-ionized water.
iv) Drying the filtrate at 80°C for overnight.
5. The process for the synthesis of graphene nano composite
based additive for lubricant as claimed in claim 1
wherein the synthesis of lubricant comprises following
steps:

i) Removing all the volatile impurities from the fatty
acid co-functionalized thermally reduced nitrogen
doped graphene by keeping in vacuum oven at 120oC for
6 hrs ii) Adding the fatty acid co-functionalized thermally
reduced nitrogen doped graphene powder to the
automobile lubricant oil (0.1 wt%). iii) Agitating the above mixture at 15oC - 26oC for 1 h.
followed by ultrasonically agitating at 600-1500W for
2 hrs at room temperature, iv) Stirring the aforesaid composition at 300-3000 RPM
for 12 Hrs to get graphene nano-composite/derivative
lubricant composition.
6. Graphene Nano composite based additive for lubricant as claimed in claim 5 possesses enhanced anti-wear properties.
7. Graphene Nano composite based additive for lubricant as claimed in claim 5 possess enhanced tribological properties.