Study On Grinding Performance Of Internal-cooling Wheel With Water-based Nanofluids

Nickel-based superalloys have excellent high-temperature strength,thermal stability and thermal fatigue resistance.They are mainly used in hot end parts such as turbine blades,turbine discs and drive shafts of engines in the aviation industry.In order to obtain prominent processing quality and high dimensional accuracy,the grinding process is usually arranged in the final stage of its machining.However,the grinding processability of nickel-based superalloys is poor.During the grinding process,the grinding force and the grinding temperature is high,thus forming a strong force-heat coupling effect.Traditionally,the coolant is sent from the outside to the grinding arc area for forced heat exchange.Nevertheless,due to the air barrier effect caused by the high-speed rotation of the wheel,it is difficult for the coolant to enter the grinding arc area effectively,and the heat dissipation efficiency is insufficient.As a result,the cooling and lubricating effect of the coolant is limited,and it is difficult to ensure the integrity of the machined surface.In view of this,this article has carried out study on the grinding performance of internal-cooling grooved wheel with water-based hybrid nanofluid for solving the problems of limited cooling and lubrication efficiency of the coolant and the difficulty of ensuring the integrity of the machined surface during the current grinding of nickel-based superalloys.First,based on the molecular dynamics method,the adsorption or dispersion behavior of the water-based nanofluid was investigated.Then the nanofluids coolant was prepared,and its chemical,thermophysical,and anti-wear or anti-friction properties were characterized.Next,on account of the phyllotaxis theory,and through the sintering and brazing process,the porous grooved abrasive ring was prepared.Ultimately,based on the prepared internally cooled slotted grinding wheel and water-based composite nanofluid,the grinding of nickel-based superalloys was carried out.Cutting test research.The main research contents of this paper are as follows:（1）Depend on the MD method,from the optimization of the dispersion of multi-walled carbon nanotubes（MWCNTs）nanofluids,the optimal mass ratio of ionic liquid（ILs）molecules 1-ethyl-3-methylimidazolium tetrafluoroborate（[EMIm]BF₄）&MWCNTs and their optimal dispersion in water were determined.Through molecular motion images,root-mean-square displacement and center-of-mass change distribution,the interaction mechanism of each component in the nanofluid was further discussed,and the mutual movement relationship（dispersion/adsorption）was obtained.In addition,the adsorption behavior of the optimized MWNCTs nanofluid system on the molybdenum disulfide（Mo S₂）interlayer and monolayer was simulated,and the formation mechanism of the laminated structure of the two kinds of nanoparticles was discussed.（2）The two types of nanoparticles MWCNTs/Mo S₂ were modified by[EMIm]BF₄ ILs,then the single-component nanofluids and composite nanofluids were prepared,and the performance tests were carried out.Among them,the dispersibility（particle size）,thermal properties（thermal conductivity,viscosity）and wettability of the metal surface（contact angle）on nanofluids with different proportions and component were compared.Further,the friction and wear test was launched.The influence of nanofluid ratio and component composition on friction coefficient,wear scar morphology,and wear scar volume wear rate were studied.（3）The design of the porous material of the abrasive-ring matrix of the internal-cooling wheel and the arrangement of the abrasive clusters on the surface were carried out.The influence of the content of Al₂O₃ hollow microspheres and powder sintering temperature on the surface of the matrix porous material,the morphology of the fracture interface,the bending strength and the wettability were studied.The arrangement of the abrasive clusters on the surface of the abrasive-ring with different diameters was designed by the phyllodes theory.The flow field model of the grinding zone based on computational fluid dynamics was established.The influence of the phyllotaxy and disorder arrangement of abrasive grain clusters and the diameter of abrasive ring on the coolant flow rate,velocity and turbulent energy in the grinding zone were researched.The porous abrasive ring was prepared by brazing diamond abrasives and assembled with the grinding wheel base to form an internally cooled grinding wheel.（4）Based on the prepared nanofluids and the internal-cooling wheel,the grinding test platform was built,and the research on superalloy internal cooling grinding processing was carried out.As a result,the influence of different processing parameters,coolants and the arrangement of abrasive clusters on the grinding temperature and the processing surface integrity parameters（surface morphology,surface roughness,surface microhardness,residual stress）was obtained.Meanwhile,the grinding mechanism of the water-based nanofluid and the internal-cooling grinding wheel was verified.