钛合金结构件磁流变电解复合抛光试验研究

Titanium alloy has the advantages of high strength, good ductility, strong corrosion resistance and elastic modulus close to human bone, which is suitable for making human lower limb joints. According to the requirements of pharmaceutical industry standards, the surface roughness Ra of joint implants generally does not exceed 0.1 μm, and the surface should be free of defects such as oxide skin, cracks, pits, edges, burrs and so on. Therefore, the high efficiency and high quality preparation of nano-scale ultra-smooth surface is the premise of achieving the wide application of titanium alloy in medicine. In order to further improve the polishing efficiency and polishing quality of titanium alloy, this article combined the high efficiency of electrolytic polishing and the high quality characteristics of magnetorheological polishing, and proposed a magnetorheological electrolytic composite polishing method for titanium alloy structural parts. The effects of electrolyte mass fraction, machining voltage, machining gap, tool speed and other polishing parameters on the surface quality of titanium alloy were discussed. The effects of different polishing parameters on the surface morphology of the titanium alloy were analyzed. The formation mechanism of the titanium alloy surface under electrolysis and magnetorheological polishing was elucidated. The feasibility of magnetorheological electrolytic composite polishing of titanium alloy artificial joint prostheses was verified. The experimental results show that with the increase of NaNO₃ mass fraction in the electrolyte, the surface roughness of titanium alloy first decreases and then increases. Under the conditions of 1.0wt.%-2.5wt.% mass fraction of NaNO₃, the titanium alloy surface quality of magnetorheological electrolysis composite polishing is better than that of magnetorheological polishing. The effects of different machining voltages on the polishing quality of titanium alloy are analyzed, and the results show that when the machining voltage is 0.1 V, the surface roughness of the titanium alloy after polishing reaches 18 nm, and the surface quality is better than that of magnetorheological polishing. Then, as the machining voltage increases, the surface roughness of the polished surface shows an increasing trend. The effect of different machining gaps on the polishing quality of titanium alloy was compared. The results show that as the machining gap increases, the surface roughness of magnetorheological electrochemical composite polishing shows a trend of first decreasing and then increasing. The effect of different machining gaps on the polishing quality of titanium alloy was compared. The results show that as the tool speed increases, the surface roughness of the titanium alloy after polishing first decreases and then increases. When the tool speed is 300 r/min, the surface roughness of the surface polishing is reduced to the minimum. A comparative experiment was conducted on the magnetorheological and magnetorheological electrochemical composite polishing of titanium alloy artificial joint prostheses. The results showed that, compared with magnetorheological polishing, the efficiency of magnetorheological electrochemical composite polishing was improved by 62.5%. At the same polishing time, the polishing quality of the magnetorheological electrolytic composite polishing process is better. The magnetorheological electrolysis composite polishing method can be used for the high efficiency and high quality polishing of titanium alloy joint prosthesiss.