Research On Microstructure And Properties Of Aluminum/Aluminum Matrix Composite Double-layer Cylinder Liner By Centrifugal Casting

With the requirements of lightweight vehicles,aluminum alloys have been widely used in the manufacture of automobile engine cylinder heads and cylinder blocks.However,as an important part of the engine,the cylinder liner is mainly made of alloy wear-resistant cast iron because of its harsh working conditions.Due to the large mass of the cast iron cylinder liner,the poor thermal conductivity,and the difference in thermal expansion coefficient between the cylinder liner and the aluminum alloy cylinder cause deformation of the cylinder liner,resulting in local heat transfer inhomogeneity and reducing engine life.This limits the development and application of "all-aluminum engines".Therefore,in order to realize the application of the "allaluminum engine",an experiment of preparing an aluminum / aluminum-based composite double-layer cylinder liner was performed in this paper.The effects of different surface treatments and preheating temperatures on the microstructure and properties of aluminum / aluminum-based composite double-layer cylinder liners were studied.An aluminum / aluminum-based composite double-layer cylinder liner casting was prepared by a combination of centrifugal casting and solid-liquid composite method.The effects of mechanical polishing,chemical method and electroplated copper on the interfacial microstructure and the mechanism of interface bonding were studied.Mechanical polishing surface treatment cannot obtain a metallurgical bonded composite interface.Interface bonding is poor and interface bonding strength is low.Both chemical method and electroplating copper surface can obtain a composite interface of metallurgical bonding.The interface bonding is better,and the surface treatment of electroplated copper obtains a higher bonding strength.A particle segregation zone is formed at the composite interface.As the distance from the interface increases,the volume fraction of Si C particles gradually increases and the hardness value increases gradually.The interface bonding of mechanical polished surface treatment is mechanical bonding.The interface bonding between chemical method and electroplated copper surface treatment is the result of fusion bonding and liquid phase diffusion interaction.Based on the chemical surface treatment method,an aluminum / aluminum-based composite double-layer cylinder liner casting was prepared by a combination of centrifugal casting and solid-liquid composite method.The effects of different preheating temperatures on the microstructure and properties of the composite interface were studied,and the effects of preheating temperature on the motion behavior of Si C particles were discussed.With the increase of preheating temperature,good metallurgical bonding is achieved at the composite interface,the gap ratio is gradually reduced,and the interface bonding strength is gradually increased.With the increase of the preheating temperature,the gradient of the volume fraction of Si C particles in the particle segregation zone became stable.With the increase of the preheating temperature,the cooling effect of the outer layer of A356 aluminum alloy cylinder liner is reduced,the melt time of the inner layer composite material increases,and the viscosity decreases slowly.The resistance of Si C particles to movement decreases,the time of movement increases,and the distribution is more uniform.