Synthesis Of Copper/Graphene Nanofluid And Its Dispersion Stability

Nanofluid is a new class of heat transfer fluid which contains suspended metallic or non-metallic nanoparticles in traditional fluid.Comparing with conventional thermal fluids and fluids containing micromete-siezd particles,nanofluids have the advantages of higher thermal conductivity,superior stability,a nd better lubricating properties.Nanofluids have potential application in many industrial sector,including daily life,transportation,industry and the field of information,so they become the hot points of material,physics,chemistry and thermal physic s.In this paper,Cu/r GO composites have been synthesized and turned into nanofluids.The mechanisms and factors of the composites preparation were introduced in the process.Pick out the material with better hydrophilia from several composites,the nanofluids prepared by this composite showed better dispersion stability and thermal conductivity.Above all,Cu/r GO composite can be formed when the molar ratio of Cu SO₄·5H₂O,KBH₄ and KOH are 1:1:23.This method has the advantage of simple,nontoxic,high yields,and can be realized at room temperature.KBH ₄ is a cost-effectiveness reductant with low consumption in preparing composites.The amount of KOH and KBH₄ and temperature can influence the reduction.And Cu NPs adhered to r GO sheets play a role in blocking r GO reunion and their sizes are around22nm.Another composite prepared by GO-100 was Cu@r GO composite.Cu@r GO composites can disperse in water due to the oxygen-containing functional groups around the r GO sheets,and the nanofluids made by Cu@r GO composite need4000rpm centrifugal speed to separate the liquid and solid.The p H value has a strong influence on the stability of nanofluids,and the system with best stability when p H=7.The nanofluids adding CTAB have better dispersion stability and need 7000rpm to separate the liquid and solid.PVP makes a steady influence on nanofluids,and adding a small amount of GA can make the nanofluids more stable.Use 2000 mesh graphite powder as crude materials via oxidation-reduction method to prepare Cu/r GO-2000 composite.This composite has better hydrophilic and can be dispersed in several polar solvents.The nanofluids with non-disperseion agent in water and p H=7 by 2min sonication,need 8000rpm to separate the liquid and solid.And the Cu/r GO-2000 composites can disperse in several polar solvents.Using ethanolamine（MEA）as the dispersant can improve the stability of nanofluids,when the nanofluids was contained 20 vol%MEA and by 2min sonication,it can not be separated at a speed of 16000rpm for 20 min.