| The surface friction and wear in the process of mechanical movement is the main reason for the failure of mechanical parts.Through the "transfer lubrication" process of solid lubricants,the self-lubricating composite material forms a solid lubricating film on the frictional contact surface which has both the shear action of bearing and consuming interfacial,so as to ensure the normal use of parts under harsh and oil-free conditions.Because of the traditional formula of material composition design of composite material self-lubricating performance has reached the bottleneck stage,based on the analysis of the contact surface micro convex body ratchet effect,on the basis of influence on transfer process of lubrication is put forward through the surface of the friction pair of micro texture,so as to realize the controllable design of ratchet effect on surface.In order to further improve the tribological properties of materials.The dissertation selects a copper-based self-lubricating composite material and uses laser processing technology to prepare micro-pits of different densities,shapes and arrangements on the surface of the matching material 45# steel to study the effect of micro-texture parameters on the friction and wear properties.The effect of surface micro-texture on the surface morphology change and transfer layer distribution of friction pairs under different working conditions was studied by using the plug-spiral friction and wear testing machine under different loads and sliding distances.In this dissertation,the finite element analysis software ABAQUS was used to establish a three-dimensional model,and the accuracy of the test results was verified by observing the distribution of stress.The main content of this dissertation are summarized as follows:(1)The laser marking machine was used to prepare micro-textures with different arrangements and densities on the surface of 45# steel,and the effect of micro-texture arrangement and micro-texture distribution density on friction and wear properties was studied.It is found that the friction performance of the textured surface is the best when the square arrangement and the micro-pit spacing is 0.4mm.(2)The laser marking machine is used to make micro-textures of three shapes(square,circle,triangle)on the surface of 45# steel.The friction and wear test was carried out on the HT-1000 friction and wear tester to verify the influence of the microtexture parameters on the surface friction and wear performance under the same test conditions.The results found that the presence of surface micro-texture can improve the wear resistance of the 45# steel surface when the test conditions remain unchanged,and different micro-texture shapes have different effects on the surface friction and wear properties.Among the three micro-textured shapes,the triangular micro-textured surface has the best effect on improving the friction and wear performance,followed by the square,and the circular micro-textured surface has the weakest effect.The surface of composite materials and textures mainly suffers from abrasive wear.(3)The triangular micro-texture as a representative to study the friction properties of the surface under different loads and sliding distances.The results found that: when the sliding distance is fixed,changing the load on the loading mechanism can change the friction and wear performance of the 45# steel surface.As the load increases,the wear resistance of the triangular micro-textured surface first increases and then decreases.When the load is 10 N,the friction performance of the surface reaches the best.The surface wear of 45# steel is mainly abrasive wear.When the load is fixed,changing the sliding distance shows that the surface tribological properties also change.Under short-distance sliding,the two pairs of surfaces are severely worn.As the sliding distance increases,a stable transfer material film is formed between the bolt-disk contact surfaces,reducing surface wear.(4)The finite element software ABAQUS was used to simulate and analyze the microtexture friction test under different shapes and loads to study the influence of different shapes and loads on the stress distribution.The simulation results show that when the load is fixed,the existence of surface micro-texture can reduce the maximum contact stress on the surface and increase the stress distribution area.It is observed that the maximum contact stress on the disk surface decreases with the increase of rotation time when the load is changed with the microtexture.(5)Comparing the results of the experiment and the simulation,it can be concluded that:on the micro-textured surface of different shapes,the degree of reduction of the maximum stress is different,resulting in different degrees of wear on the surface of the disk,and the maximum stress of the micro-textured surface is mainly distributed on the edge of the micro-textured surface.Therefore,the edge of the micro-textured is severely worn;... |
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