Study On Microstructure And Properties Of Cold Sprayed Cu-based Deposits

Cu and its alloys are applied extensively in electrical,light industry,national defense and other fields due to their excellent conductivity,corrosion resistance and machinability.However,when Cu-based deposits are fabricated using heat input coatings preparation processes and additive manufacturing processes,the characteristics of high thermal conductivity,low laser absorptivity,and easy oxidation at high temperatures of Cu and its alloys can cause defects in the microstructure of the obtained deposits.This in turn affects the properties of the deposits.Cold spraying is an emerging coating preparation and additive manufacturing technology.In cold spraying,the combination between particles in the deposits and between substrates and particles mainly depends on the kinetic energy of high-speed particles rather than thermal energy.Therefore,cold spraying technology can effectively avoid the potential problems caused by heat input coating preparation and additive manufacturing technology,and realize the rapid preparation of high-performance Cu-based deposits.In this paper,Cu-based composite coatings were prepared by cold spraying technology with different feedstock material composition ratios.The influences of different temperature annealing of Cu-based coatings were investigated.In addition,taking cold sprayed Cu-based bulk materials as the research object,the effects of conventional annealing treatment and high-energy pulse current treatment on the Cu-based bulk materials microstructure and its mechanical properties were investigated.In this paper,the main contents are as follows:(1)Preparation of cold sprayed Cu-based coatings with different feedstock powders composition ratios and research on corrosion resistance of the coatings.Cu-based composite coatings with different composition ratios were prepared by cold spray system,and the effects of feedstock material composition ratios on the Cu-based coatings were studied.The results showed that the coatings obtained in the experiments all have relatively dense structures,but due to the different deposition abilities of different particles,the element contents of the coatings were slightly different from that of the feedstock materials.The phenomenon of work hardening resulted in coatings exhibiting high microhardness.Changes in the composition ratio of feedstock materials affected the particles deposition behavior during spraying,resulted in differences in microhardness between coatings.The corrosion resistance of the coatings was significantly affected by the proportion of feedstock materials.The reasonable composition ratio could change the corrosion behavior and effectively improve the corrosion resistance of the coatings.(2)The effects of annealing treatment on the cold sprayed Cu-based coatings.The cold sprayed Cu-based coatings were annealed at different temperatures,and the influences of annealing on the coating microstructure and its properties were investigated.The results showed that the annealing treatment could promote the evolution of the coatings microstructure through element diffusion and change the bonding state between the substrate and cold sprayed Cu-based coating.Appropriate annealing temperature could improve the compactness of the coatings,effectively reduced the corrosion rate of the coatings,and improved the corrosion resistance of the coatings.In addition,the evolution of the microstructure and microhardness of the coatings after annealing affected the wear resistance of the coatings.Based on good particles bonding state,the wear resistance of the Cu-based coatings was improved due to the high microhardness.(3)The effect of annealing treatment and high-energy pulse current treatment on the microstructure and mechanical properties of CSAM Cu-based materials.The original mechanical properties of the materials were characterized,and the properties of the Cu-based materials were studied after annealing at different temperatures and treating at different high-energy pulse current parameters.The reason for the change of mechanical properties of the CASM Cu-based material was analyzed through the evolution of microstructure.The results showed that reasonable annealing and high-energy pulse current process could effectively repair the particles boundary and promote the recovery and recrystallization of the material.As a result,the microstructure of the Cu-based bulk material was improved,and the mechanical properties were improved.