Duplex Polishing Processing And Surface Morphology Evolution Of TC4 Alloy

The electropolishing device is simple and the process is rapid,but the processing accuracy is only in the micron level.Ion beam polishing has the processing accuracy of atomic and molecular level,but the equipment is complex and time-consuming.Based on the characteristics of two polishing methods,a new duplex polishing process for TC4 alloy is proposed.Electropolishing is used as rough polishing method,and ion beam polishing is used as fine polishing method in order to achieve rapid and precise polishing of TC4 alloy.In the process of electropolishing,the appropriate electrolytic voltage is determined by measuring the anodic polarization curve,and then the influence of solution ratio and electrolytic time is explored by single factor experiment.Finally,the optimal parameters are determined by orthogonal experiment.In the research of ion beam polishing process,the optimal polishing time is determined by segmenting ion beam polishing with high energy and large beam current on the surface with roughness of 1.5?m,as a comparison with the duplex polishing process.Then,on the basis of electropolishing parts,the optimum process parameters of ion beam polishing in duplex polishing process are explored from three aspects:ion beam energy,ion beam current and polishing time.In this paper,the surface morphology and roughness of the workpiece are measured by laser scanning confocal microscope and atomic force microscope,and the surface composition is detected by scanning electron microscope.When measuring the polishing rate,the weight reduction of the workpiece at different times is measured with a precision balance of 1/10~5 to characterize the polishing rate.It was found that the optimum electropolishing process for perchloric acid-methanol electrolyte system was 1:11 ratio of perchloric acid to methanol,32V electrolytic voltage and 55s electrolysis time.Under the optimum electrolytic polishing parameters,the surface roughness of the workpiece after electrolysis can be reduced to 0.38?m,which is 1/2 lower than that of the perchloric acid-aceticacid electrolyte system.The influence degree of each parameter on the electropolishing result,which is from primary to last,is solution ratio,electrolysis voltage and electrolysis time.The optimum parameters of ion beam polishing are 500 eV ion beam energy,130 mA ion beam current and 65 degrees ion beam current.After polishing for 1 hour,the surface roughness of the workpiece can be further reduced to 7.1nm.Compared with the single ion polishing process of rough surface,the polishing time is much shorter than that of 7 hours.In the study of ion polishing rate,it is found that the rate of ion polishing is faster in the initial stage,and then slows down gradually.In the initial stage of ion beam polishing with sputtering as its dominant role,the surface presents island morphology.Subsequently,the surface viscous flow and atom diffusion are gradually enhanced,and the voids around the island are gradually filled up,and gradually evolve into corrugated morphology.As the ripple becomes wider,ion beam polishing eventually forms a flat surface.