Rapid Grinding Of Diamond And Preparation Of Graphene Coatings Based On Mechanochemistry

Mechanochemistry takes advantage of mechanical energy to induce chemical reactions or induce variation of properties,structure,and microstructure,to modify materials or prepare new materials.In this paper,rapidly grind diamond and prepare a graphene coating with interfacial adhesion can be obtained by the mechanochemical effect.In recent year,the applications of diamond achieve rapid development.The precision or even ultra-precision machining of the diamond is required in various application requirements.However,due to the hardest property of diamond,it is difficult to machine diamond.Therefore,the high efficient machining has become an urgent problem to be solved which limits the widely practical application of the diamond.In this paper,a novel grinding wheel designing concept is proposed to solving the problem that the low removal rate in the mechanochemical polishing techniques.By adding Fe or Ti into the metal/vitrified bond wheel,the novel grinding wheel is prepared.With the help of mechanochemical effect,the Fe/Ti induces conversion of diamond carbon into nondiamond carbon,which greatly enhances the removal rate of diamond.The removal rate of the metal/vitrified bond wheel with Fe is 70.32?m?h^-1 and 78.30?m?h^-1,respectively.Based on the abovementioned,the Ce element is added to the Fe-containing metal/vitrified bond wheel,which can further enhance the removal rate.The removal rate of diamond can reach up 110?m?h^-1.XRD and TEM results reveals that with the rotational speed increasing,the diamond can first react with Fe to form the Fe₂C,and then the Fe element can induce the graphitization of diamond.Moreover,the investigation of diamond surface damage layer shows that the surface damage layer is⁵0 nm after the formation of carbide,whilst that after the graphitization is 1?m.The removal rate of the metal/vitrified bond wheel with Ti is 56.35?m?h^-1 and 120.21?m?h^-1,respectively.The results reveal that the Ti element can induce graphitization of diamond,and then graphite reacts with Ti forming TiC.Moreover,the graphitization can deepen the diamond surface damage,reaching¹.5?m.At present,the principal preparation of graphene coating is chemical vapor deposition?CVD?.However,the strict request for the matrix,the high demand for the equipment,and the high cost can largely limit the actual application of the graphene.In particular,for the CVD method,the bond force between graphene coating and the metals is weak.To solve the problems in the preparation of the graphene coating,a novel preparation method is proposed,and the interface structure and the performance of graphene in anticorrosion and antifriction are studied.In this work,the 304 stainless steel balls?SS?are chosen as the grinding ball,and reduced graphene/graphite as the grinding media.By the simple ball-milling method,the graphene coating is successfully prepared on the SS surface,and the morphology and anticorrosion property of the graphene coating are characterized.XRD and TEM results show that the graphene coating is strongly bonded to the SS via Cr-C bonding,which provides the robust adhesive attraction of interface.The corrosive tests show that the corrosion rate of the graphene covered SS could reduce up to 20 times by decreasing the anodic reaction in the 3.5 wt.%NaCl solution.The nanoscratching tests show that the graphene coating can significantly decrease the wear rate from 6.45?10^-13 to4.31?10^-13 m²?N^-1.Similarly,the Cr or Ti elements modified mild steel balls?MS?are chosen as the grinding ball,and the reduced graphene coating as the grinding media.By the simple mechanical balling,the graphene coating is successfully prepared on the Cr/Ti modified MS.The results show that the graphene also strongly bonded to metal substrate via covalent bonding.The corrosive results show that the graphene coating could efficiently enhance the anticorrosion property of the MS by slow down the anodic reaction in the 3.5 wt.%NaCl solution,and the anticorrosion property improved for about 100times.Graphene coating can significantly decrease friction of coefficient from 0.225 to0.18.Moreover,the graphene is directly prepared on CoCrFeMnNi HEA micro/nanoparticles?Gr/FMH?by in situ mechanical exfoliation of graphite crystal.The results show that the anticorrosion property of the prepared Gr/FMH composite particles is significantly improved compared with the FMH particles in the 0.1 mol?L^-1 H₂SO₄solution.Furthermore,the Gr/FMH alloy is prepared by the spark plasma sintering?SPS?.Compared with the FMH alloy,the hardness of the SPS-ed Gr/FMH alloy is significantly improved by about 2.33 GPa,and the wear resistance of the SPS-ed Gr/FMH alloy is also significantly improved.Moreover,the compressive yield strength of the Gr/FMH alloy achieves 1350 MPa at room temperature.The strengthening mechanism is grain boundary strengthening and precipitation strengthening.