Effect Of Annealing Process And Coarsening Treatment On Microstructure And Properties Of Rolled Silver-copper Foil

Rolled copper foil is widely used in aerospace,electrical instruments,new energy vehicles and other fields because of its good electrical and thermal conductivity and excellent bending resistance.Copper foil is formed by cold rolling process,which has the problem of low elongation.In addition,the low surface roughness of rolled copper foil leads to its low peel strength.At present,the elongation is mainly improved by annealing treatment,and the peel strength is improved by coarsening treatment.Therefore,this paper takes rolled silver-copper plate and silver-copper foil as research objects,and studies the evolution law of microstructure and properties of rolled silver-copper plate and silver-copper foil during annealing and coarsening treatment.In this paper,the rolled silver-copper plate and silver-copper foil are annealed in a tubular furnace,and the silver-copper foil is coarsened by a direct-current power supply.Scanning electron microscope,X-ray energy spectrometer,Vickers hardness tester,electrochemical workstation,electronic universal testing machine,bending resistance tester and other testing methods were used to characterized the annealed copper plate and copper foil and the coarsening layer on the surface of copper foil.The experimental results show that the grain morphology changes from rolled strip grain to equiaxed grain during annealing,and the texture types change from copper texture,brass texture,S texture and R texture to cubic texture and{025}<001>texture during annealing.The texture content of annealing increased first and then decreased with the annealing temperature increasing.When the annealing temperature increases,the grain boundary content of small angle decreases,but that of large angle increases.When the annealing temperature increases from 240?to 410?,the Vickers hardness of the silver-copper plates decreases.When annealed at 240-410?,the corrosion resistance of silver-copper plate showed a trend of weakening first and then strengthening with the increase of annealing temperature.The silver-copper plate was held at 300?for 10 min with the highest content of cubic texture and a hardness of 60 HV,showing good corrosion resistance.The annealing texture of rolled silver-copper foil is mainly cubic texture.With the increase of annealing time,the deformation texture content decreases and the annealing texture content increases.The content of large angle grain boundary increased gradually with the increase of annealing time.The?3 grain boundary content of silver-copper foil held at 180?for 10 min reached the maximum.The tensile properties and bending properties have obvious anisotropy.When annealing for 1-5 min,the tensile strength and bending times of silver-copper foil decrease sharply with the extension of annealing time.When annealing for 5-60 min,the tensile strength tends to be stable(RD170 MPa,TD130 MPa),with the extension of annealing time,but the bending times increase slightly.The electrical conductivity had no anisotropy and increased with the extension of holding time.The corrosion resistance of annealed silver-copper foil is better than that of rolled silver-copper foil.The corrosion resistance of the annealed silver-copper foil held at 180?for 10 min is the best.The results of orthogonal test show that H₂SO₄ concentration and EDTA-2Na content are the main factors affecting the micro-morphology of the roughened layer.When H₂SO₄ concentration is 120 g·L^-1 and EDTA-2Na content is 1.5 g·L^-1,the roughened layer has fine grains and high roundness.The grain size decreases with the increase of current density and increases with the increase of Cu²⁺concentration.Without EDTA-2Na,the roughened layer is composed of Cu,and after EDTA-2Na is added,the roughened layer contains Cu,Cu O and Na.The surface roughness of roughened layer decreases with the increase of current density.With the increase of Cu²⁺concentration,the corrosion resistance of the roughened layer first decreases and then increases.