| How to make breakthroughs in the high-precision and high-efficiency surface finishing technology,and how to improve the surface quality,service performance,and life of special components products have become urgent issues to be solved in the development process of China’s new manufacturing industry.Magnetic abrasive finishing（MAF）technology,as a new type of surface finishing technology,has unique advantages such as high machining accuracy,good shape replication（adaptability）,flexible processing,low temperature rise,simple process,high efficiency,wide adaptability,and low cost,and has good development prospects.Magnetic abrasive,as the“tool”of magnetic abrasive finishing,can remove surface defects of workpieces with high precision and efficiency through the driving force provided by the magnetic pole.However,traditional magnetic abrasives have problems such as irregular shape,unreasonable distribution of abrasive phases,and poor combination of two phases due to factors such as preparation technology and material properties,while magnetic pole design has problems such as mismatch between magnetic induction intensity and magnetic field gradient,resulting in low abrasive pressures and serious impact on the machining accuracy and stability of magnetic abrasive,making it difficult to meet the needs of industrial applications of magnetic abrasive finishing technology.To address the complex preparation process,easy detachment of the grinding phase,and low service life of magnetic abrasives,as well as the defects in magnetic pole design such as the mismatch between magnetic induction intensity and magnetic field gradient,this study utilized ANSYS Maxwell software to simulate and optimize the layout,quantity,and size of a dual-disc magnet,optimizing the distribution of magnetic induction intensity and gradient magnetic field.The study then combined iron-based Si C abrasives with the optimized design of the dual-disc magnet to conduct grinding experiments on the surface of TC4 titanium alloy rods,exploring the optimal process parameters.Additionally,the study used mechanical alloying and sintering technology to prepare core-shell Fe-Si magnetic abrasives with high magnetic conductivity and surface hardness,using silicon as an alloying element and spherical iron powder as a matrix,forming Fe-Si intermetallic compounds（Fe Si,Fe3Si,etc.）on the surface of the spherical iron powder.Based on thermodynamic analysis during the preparation process,the study explored the impact of mechanical alloying,iron-silicon mass ratio,and sintering temperature on abrasive phase,as well as the effect of Fe3Si and Fe Si content and sintering temperature on alloy layer thickness,magnetic conductivity,and nanohardness of the abrasive.Finally,the study compared the processing performance,magnetic performance,and service life of the Fe-Si-based magnetic abrasive with iron-based Si C abrasive,with the main research results summarized as follows:（1）This article uses magnetic field simulation optimization to control magnetic induction and magnetic field gradient under different parameters such as magnetic pole quantity,size,and arrangement.The double-disc magnetic pole has a magnetic induction strength of 0.63-1.18 T and a magnetic flux increment of 24.515 T·mm,achieving the best magnetic induction strength and magnetic field distribution.Meanwhile,iron-based Si C abrasive is used to explore its optimal process parameters.Compared with the“grinding-type”magnetic pole,the optimal surface roughness（Ra0.354μm）of the double-disc magnetic pole is improved by 21.51%,and the grinding efficiency is increased by 18.32 times,indicating that the double-disc magnetic pole has good processing accuracy and extremely high processing efficiency.（2）Based on the design principles of high magnetic permeability and high surface hardness,Fe-Si-based magnetic abrasive is designed and prepared by thermodynamic analysis of the formation process of the alloy layer Fe3Si and Fe Si.The effect of the iron-silicon mass ratio and sintering temperature on the phase composition of the abrasive is investigated.Quantitative analysis by XRD shows that when the iron-silicon mass ratio is 6:1 and sintered at 950℃for 4 hours,the Fe3Si and Fe Si content is 74%and 26%,respectively,and the alloy layer thickness is about 10μm.The saturation magnetization of the abrasive is 193.583 emu/g,only a 4.63%decrease compared to the original iron powder.The nanohardness of the two-phase alloy layer is 9.620 and4.298 GPa,respectively,which is much higher than the average nanohardness of the matrix（3.082 GPa）.Fe-Si-based magnetic abrasive has high hardness and good magnetic permeability,which can meet the needs of processing performance.（3）By comparing the grinding performance and effects of the two types of abrasives,the surface Ra of the titanium rod machined by Fe-Si-based magnetic abrasive decreases from 0.965μm to the lowest value of 0.285μm,with a surface Ra improvement rate of 67.46%.Compared with iron-based Si C abrasive,the surface Ra of the titanium rod is improved by 19.94%.The saturation magnetization of Fe-Si-based magnetic abrasive is 193.584 emu/g,15.07%higher than that of iron-based Si C abrasive（168.225 emu/g）,indicating better magnetic permeability.Meanwhile,Fe-Si-based magnetic abrasive has a grinding life of about 120 min,nearly twice as that of iron-based Si C abrasive,demonstrating excellent grinding life. |
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