Study On Preparation Technology Of Continuous Carbon Fiber Reinforced Aluminum Wire

To achieve a good combination between carbon fiber and aluminum matrix is the key to promote the wide application of continuous carbon fiber reinforced aluminum conductor in the wire and cable industry.In this paper,the unidirectional continuous carbon fiber treated by electroless nickel plating with electromagnetic stirring is used as the reinforcing phase,pure aluminum is used as the matrix,and the continuous carbon fiber reinforced aluminum matrix composite is prepared by gravity casting+hot extrusion/cold drawing method.The effects of technological parameters on the surface micro morphology and deposition rate of continuous carbon fiber under the condition of electromagnetic stirring plating were studied;the microstructure,properties and interface structure of the as cast and as processed state composites are analysed.It provided reference for the application of continuous carbon fiber reinforced aluminum matrix composite.The main study conclusions are as follows:（1）When stirring speed was constant,with the increase of plating time,bath temperature,and bath pH value,the carbon fiber surface coating became uniform and complete gradually,and the coating thickness increased gradually;but when the plating time exceeded 20 minutes,the bath temperature exceeded 75℃,and the bath pH value exceeded 8,a large number of cellular nickel particles with different shapes were deposited on the surface of the coating,and then a rough surface morphology was formed.The deposition rate of the coating increased with the increase of bath temperature and bath pH.When the stirring speed increased from 200 rpm to 300 rpm,the deposition rate of the coating increased with the increase of stirring speed.However,when the stirring speed increased from 300 rpm to 400 rpm,the deposition rate of the coating decreased with the increase of the stirring speed.It can be therefore concluded that the optimum process parameters of electroless nickel plating on continuous carbon fibers surface with electromagnetic stirring are plating time 15 to 20 minutes,bath temperature 75℃,bath pH value 8,and stirring speed 200～250rpm.The nickel coating obtained under the optimum technological conditions is compact,uniform and complete,and there is no black center in the inner part of carbon fibers.（2）When the nickel plated carbon fiber is heated at 100℃,the structure of the coating will not change;When the heating temperature at 200～300℃,Ni₃P compound phase will appear in the coating;When heating temperature at 400℃,Ni element in the coating will react with O₂ at high temperature to form Ni O compound phase.In the preparation of Cf/Al composite,200℃～300℃can be used as the best preheating temperature range for nickel plated carbon fiber.（3）In the continuous Cf/Al composite prepared by gravity casting,there are mainly un-infiltrated and void defects.Its tensile strength is 81.8%～92.5%of that of aluminum matrix,and its elongation is 75.2%～78.1%of that of aluminum matrix.（4）In the as cast Cf/Al composite,there are three distribution forms of coating in the aluminum matrix:undissolved and diffused,semi dissolved and diffused,fully dissolved and diffused.The interface mechanism is one or more mixing mechanisms of mechanical combination,dissolution and wetting combination,and reaction combination.Among which the reaction combination depends on the combination of Al_1.1Ni_0.9 phase reaction layer formed by chemical reaction between Al and Ni.（5）After the as cast composite is deformed by hot extrusion with more than 93%deformation,the un-infiltrated defects inside the carbon fibers disappeared,but the continuous carbon fiber is easy to fracture.After the as cast composite is deformed by cold drawing with 80%deformation,the inner part of carbon fibers has the evolution process from un-infiltration defect disappearing gradually to un-infiltration defect disappearing completely,and then the coating on the surface of carbon fiber has fallen off and broken.（6）After the as cast composite is deformed by 40%cold drawing deformation,the carbon fibers inside the composite are uniform and dense,and there are no un-infiltrated defects in the inner of carbon fibers.In addition,the Al matrix region and Ni-C enrichment region in the as drawn composite depend on the combination of Al_0.42Ni_0.58phase reaction layer,meanwhile there is C₂Ni O₄ phase in the Ni-C enrichment region.The interface bonding mechanism of carbon fiber and coating changes from the initial mechanical bonding to reactive bonding.