Title of Invention

MAGNETIC NANOFLUIDS AND A PROCESS FOR THE MANUFACTURE THEREOF

Abstract

A process for the manufacture of magnetic nanofluid comprising the catalytic decomposition of a hydrocarbon, selected from acetylene, methane and ethylene over alloy hydride, selected from Zr based and rare earth based metal hydrides carried out to obtain magnetic nanowire filled MWNT, the growth of magnetic metal filled MWNT being carried out in a quartz boat in a single-stage furnace with precisely controlled temperatures ranging between 950 degree C and 960 degree C with fine powders of alloy hydride selected from metal hydride systems as catalyst; introducing hydrogen for removing the presence of any oxygen on the surface of the alloy hydride catalyst; stopping the hydrogen flow thereafter; heating the furnace to a predetermined growth temperature between 950 degree C and 960 degree C followed by the introduction of the hydrocarbon, the pyrolysis being carried out over a predetermined interval of time, between 20 minutes and 30 minutes, cooling the furnace thereafter to room temperature, maintaining the flow of argon throughout the process; and purifying the carbon soot to obtain MWNTs filled with magnetic nanowires; functionalising the said MWNT with carboxyl, hydroxyl and carbonyl groups, selected from oxygen containing functional groups by treating with concentrated acids selected from H2SO4, HNO3 or both to result in the attachment of functional groups, namely, -OH5 -C=O5 -COOH to the external walls of the CNTs rendering the CNTs more stable and dispersible in

Full Text

This invention relates to magnetilc nanofluids and a process for the manufacture thereof involving the synthesis of multiwalled carbon nanotubes (MWNT) based magnetic nanofluids where magnetic nanowire filled CNTs are synthesized by catalytic CVD technique over AB3 alloy hydrides. These as-grown magnetic nanowire filled CNTs are usually in an entangled state and not ready for uniform dispersion in the desired fluid. Hence as-grown CNTs have been purified and functionalized with selected functional groups which make these MWNT stable and dispersible uniformly in base fluid to obtain CNT based magnetic i nanofluids. This invention relates to the synthesis of magnetic nanowire filled MWNT and preparation of magnetic nanofluids by functionalizing magnetic metal encapsulated MWNT with selected functional groups. There is a need for new and innovative coolants with improved performance. The present invention pertaining to nanofluids - heat transfer fluids containing suspensions of nanoparticles is proposed as means for meeting these challenges. Nanofluids, that is fluid suspensions of nanometer - sized solid particle$ and fibers, surpass the performance of heat transfer liquids currently available. Recent experiments on nanofluids indicate significant increases in thermal conductivity compared with liquids without nanoparticles or larger particles, strong temperature dependence of thermal conductivity. Conventional particle-liquid suspensions require high concentrations (>10%) of particles to achieve such enhancement. Key features of nanofluids that have been reported so far include thermal conductivities exceeding those of traditional solid/liquid suspensions. Each of these features is highly desirable for thermal systems; a stable and easily synthesized fluid with these attributes and acceptable viscosity would be a strong candidate for the next generation of liquid coolants. Magnetic nanofluids are magnetic soft - matter materials with magnetically controllable fluid properties having wide range of technological arid biomedical applications. Magnetic nanofluids boil in applied magnetic fields and have magnetically controlled boiling in reduced gravity conditions. In addition, the j flow properties and dynamic viscosity can be changed with particle volume fraction. It is thus an object of this invention to propose a process for synthesizing magnetic nanowire filled MWNT by simple chemical vapour deposition and preparation of magnetic nanofluids by functionalizing magnetic metal encapsulated MWNT with selected functional groups. The present invention employs a process wherein a hydrocarbon is catalytically decomposed over Mm based. alloy hydride in order to get magnetic nanowire filled MWNT. The growth of magnetic metal filled MWNT has been carried out using a single-stage furnace with precisely controlled temperatures using fine powders of alloy hydrides as catalysts. EXAMPLE The catalytic decomposition of a hydrocarbon, selected from methane/acetylene/ethylene over Mm based alloy hydride, namely, MmNiz is carried out to obtain magnetic nanowire filled MWNT, the growth of magnetic metal filled MWNT being carried out in a quartz boat in a single-stage furnace with precisely controlled temperatures ranging between 950 degree C and 960 degree C with fine powders of selected alloy hydride, namely. MmNiz as catalyst. Other hydrocarbons that can be used are LPG. So also, other alloy hydrides that can be used are Zr based alloys, rare earth based alloys, ZrMnFe2. Hydrogen is introduced in the quartz boat for 1 hour, for removing the presence of any oxygen on the surface of the alloy hydride catalysts. The hydrogen flow i$ stopped and the furnace heated to a predetermined growth temperature between 950degree C and 960 degree C followed by the introduction of the hydrocarbon, namely, C2H4. The pyrolysis is carried out over a predetermined interval of time, namely, 20 mins. The furnace is cooled thereafter to room temperature. Flow of argon is maintained throughout the process; and the carbon soot obtained in the quartz boat is purified and analysed revealing that the MWNTs thus produced are filled with magnetic nanowires. MWNTs as produced are usually entangled and not readily . dispersible in fluids. Accordingly the CNTs are functionalised with carboxyl, hydroxyl and carbonyl groups, selected from oxygen containing functional groups by treating with concentrated acids selected from HNO3, H2SO4 or both to result in the attachment of functional groups, namely, -COOH -C = O,-O-H to the external walls of the CNTs which make the CNTs more stable and dispersible in the selected liquids, such as, deionized water and ethylene glycol to obtain homogeneous CNT magnetic nanofluids. The terms and expressions herein do not restrict this invention to what has been described, having regard to the scope of this invention. We Claim: 1. A process for the manufacture of magnetic nanofluid comprising the catalytic decomposition of a hydrocarbon, selected from acetylene, methane and ethylene over alloy hydride, selected from Zr based and rare earth based metal hydrides carried out to obtain magnetic nanow re filled MWNT, the growth of magnetic metal filled MWNT being carried out in a quartz boat in a single-stage furnace with precisely controlled temperatures ranging between 950 degree C and 960 degree C with fine powders of alloy hydride selected from metal hydride systems as catalyst; introducing hydrogen for removing the presence of any oxygen on the surface of the alloy hydride catalyst; stopping the hydrogen flow thereafter; heating the furnace to a predetermined growth temperature between 950 degree C and 960 degree C followed by the introduction of the hydrocarbon, the pyrolysis being carried out over a predetermined interval of time, between 20 minutes and 30 minutes, cooling the furnace thereafter to room temperature, maintaining the i flow of argon throughout the process; and purifying the carbon soot to obtain MWNTs filled with magnetic nano wires; functionalising the said MWNT with carboxyl, hydroxyl and carbonyl groups, selected from oxygen containing functional groups by treating with concentrated acids selectedJfrom H2S04, HN03 or both to result in the attachment of functional groups, namely, -OH, -C=0, -COOH to the external walls of the CNTs rendering the CNTs more stable and dispersible in liquids selected from deionised water and ethylene glycol to obtain homogeneous CNT magnetic nanofluids. i 2. A process as claimed in claim 1, wherein the alloy hydrides are free from oxidation with catalytically active surfaces. 3. A process as claimed in claim 1, which involves a single in situ filling of magnetic wires in MWNT. I j 4. A process as claimed in claim 1, wherein the said alloy hydride catalysts are removed from the as-grown carbon nanotubes, during purification. 5.A process for the manuiacture of magnetic nanofluid I substantially as herein described and illustrated. I 6. Magnetic nanofluid whenever manufactured by a I t process as claimed in any one of the preceding Claims.

Documents:

408-CHE-2008 AMENDED PAGES OF SPECIFICATION 25-11-2014.pdf

408-CHE-2008 CORRESPONDENCE OTHERS 25-11-2014.pdf

408-che-2008-claims.pdf

408-che-2008-correspondnece-others.pdf

408-che-2008-description(complete).pdf

408-che-2008-form 1.pdf

408-che-2008-form 18.pdf

408-che-2008-form 26.pdf