| Ni-Cr alloy Inconel 625 has good tensile strength,yield strength,good machinability,weldability and good high temperature corrosion resistance,which is widely used in aerospace,chemical,petrochemical and marine applications.Due to the poor tribological properties and vibration and noise performance,Inconel 625 is only used in sliding parts such as guide slides through oil/grease lubrication.In the application fields of aerospace and marine engineering,oil lubricant failures often occur in Inconel625 components.Therefore,it is of great significance to study a method that can effectively improve the tribological properties of Ni-Cr alloy Inconel 625.In recent years,surface texture and solid lubrication have become important directions to improve tribological properties of materials.In this thesis,aiming at the problems existing in the tribological properties and vibration and noise performance of sliding parts(guide rails and sliders),a groove textured self-lubricating composite surface with good tribological properties and vibration and noise performance was designed and prepared based on Ni-Cr alloy Inconel 625,and the friction and wear mechanism and vibration and noise reduction mechanism were analyzed.The main contents and conclusions are as follows:(1)Textured samples with grooves(GTA)and self-lubricating composite samples(CASs)were prepared by wire cut electrical discharge machining and vacuum pressure infiltration technology.Through Box-Behnken orthogonal test analysis,the grooves can effectively reduce friction coefficient of samples.Through the regression analysis of three factors of groove parameters,the regression equation of friction coefficient with groove width(W),surface density(D)and groove depth(H)was obtained.For single texture density,GTA-15(W=300μm,D=15%,H=500μm)has the best comprehensive performance,and the friction coefficient and wear loss are 0.57 and0.523 mm~3,respectively.For the composite texture density,GTA-25&20(W=300μm,H=500μm,D1=25%,D2=20%)has the best comprehensive performance,the friction coefficient and wear loss are 0.52 and 1.0393 mm~3,respectively.Through the friction mechanism and stress-strain analysis of different texture densities,the main role of grooves in friction process is to improve the state of wear surface by capturing wear debris of Inconel 625 matrix,which can stabilize friction coefficient,inhibit severe abrasive wear and improve adhesion wear.(2)Through friction and wear test analysis,the tribological properties of self-lubricating composite samples(CASs)are better than smooth surface(SS).For self-lubricating composite samples with single texture density,CASs-25 had the best tribological performance.Compared with SS,the average friction coefficient decreased by 47%(0.33)and the wear loss decreased by 97%(0.00962 mm~3).For the self-lubricating composite sample with composite density,CASs-25&33 has the best tribological performance,and the average friction coefficient is 0.30,wear loss is0.00852 mm~3(3)The analysis of wear morphology and stress-strain shows that SS exhibits severe adhesive wear and abrasive wear.With the increase of texture density,wear mechanism of the sample will gradually transit to slight abrasive wear.When the texture density is too large,wear mechanism will be transformed into abrasive wear and fatigue wear,which will cause the spalling and fracture of lubricating layer,thereby deteriorating wear surface.The lubrication mechanism of self-lubricating composite sample is the result of synergistic effect of solid lubricant SAC and grooves.The self-lubricating composite surface(CASs-25&33)with composite texture density has better tribological properties,which is mainly due to solid lubricant can spread to form a more uniform and moderate thickness lubrication layer to avoid fatigue fracture and spalling.(4)Through collection and analysis of friction vibration and noise signals,compared with vibration and noise performance of SS,self-lubricating composite samples(CASs)show inhibitory effect on vibration and noise,and CASs-25&33 has the best vibration and noise reduction performance.The main frequencies of noise and vibration signals of self-lubricating composite samples move to low frequency region,and the amplitude is greatly reduced,indicating that self-lubricating composite surface has a particularly prominent inhibitory effect on the high-frequency vibration and noise signals.(5)The soft-hard alternate composite surface formed by solid lubricant SAC and Inconel 625 destroys the interface continuity,so that the friction force forms regular multi-segment fluctuations in a stroke,which can inhibit the self-excited vibration in the process of reciprocating motion,thereby inhibiting the high-frequency vibration and scream.The synergistic effect of grooves structure and solid lubricant SAC effectively inhibits the generation of vibration and noise.The improvement of wear surface can effectively reduce the random collision of the grinding ball on the Inconel625 friction interface,lower the irregular vibration of the friction pair,press the energy generated by the collision of the grinding ball and the sample,and effectively decrease the noise intensity.This thesis provides a new idea to improve the tribological properties of Ni-Cr alloy,enriches the research of solid lubricant and surface texture in friction vibration and noise control,and provides an effective method to suppress vibration noise.It could provide practical reference and theoretical reference for solving the engineering application of Inconel 625 in sliding parts(slider,guide rail). |
