抛光垫表面微细结构对抛光性能的影响试验

抛光垫是影响抛光加工效率和表面质量的关键因素之一，但影响规律和作用机理尚不清晰。为研究抛光垫表面微细结构对抛光性能的影响规律，制作有、无固结磨料的表面六边形微细结构抛光垫，分别对YG15硬质合金、单晶Si和单晶4H-SiC三种硬度差异较大的工件进行抛光试验。结果表明：各抛光垫对不同硬度工件抛光效果的影响规律一致，随着抛光工件的硬度增大，各抛光垫的材料去除率（MRR）减小，表面粗糙度Ra增大。抛光垫内的固结磨料能将MRR提高5～10倍，但也会导致Ra增大5～20倍。抛光垫表面微细结构会使得抛光过程中有效接触面积Ap和有效磨粒数Ns减小而导致MRR下降，而抛光垫硬度的增加能够部分弥补抛光垫表面微细结构造成的影响，抛光工件硬度越大，弥补效果越好。增加游离磨料能够有效降低抛光后Ra并提高硬度较大工件的MRR（上升约8%），但对硬度较小工件的MRR有抑制作用（下降约27%）。根据抛光试验结果，建立工件-磨料-抛光垫接触模型，深入分析抛光垫表面微细结构、表面硬度对不同硬度工件抛光MRR和表面质量的作用机理，为不同工件抛光时抛光垫的选择提供了理论基础。

Experiment on the Effect of Polishing Pad Surface Microstructure on Polishing Performance

A polishing pad is an important component of the polishing process, and its performance is influenced by such factors as the material, surface texture, and structure. The surface pattern of the polishing pad stores and transports the polishing solution and carries away the polishing chips. The surface pattern of the polishing pad has a significant influence on the efficiency and surface quality of the polishing process, but the mechanism of its action remains unclear. To study the influence of the polishing pad surface microstructure on polishing performance, a surface hexagonal microstructure polishing pad with and without a consolidated abrasive was produced. Polishing experiments were performed on three types of workpiece with different hardnesses - YG15 cemented carbide, single-crystal Si, and single-crystal 4H-SiC - using a plain structured polishing pad (P1), an unconsolidated abrasive surface microstructure polishing pad (P2), and a fixed abrasive surface microstructure polishing pad (P3). Based on the experimental results, a workpiece-abrasive-polishing-pad contact model was established to analyze the mechanism of the polishing pad surface microstructure and surface hardness on the polishing material removal rate (MRR) and surface quality of workpieces with different hardnesses. The results show that the effects of the three polishing pads on the polishing effect of workpieces with different hardness values are consistent. As the hardness of the polished workpiece increases, the MRR of polishing decreases significantly, and the surface roughness Ra increases. The MRR is increased 5-10 times by the consolidated abrasive in the polishing pad, but the consolidated abrasive also leaves many scratches on the surface of the workpiece, while the workpiece surface roughness also increases 5-20 times. The microstructure of the polishing pad surface reduces the effective contact area Ap and effective number of abrasive grains Ns during the polishing process, resulting in a lower MRR for P2 than for P1. However, the increased hardness of the polishing pad increases the depth of cut hw of the abrasive, which compensates for the reduced MRR caused by the microstructure of the polishing pad surface. The harder the polished workpiece, the better the makeup effect. For P3, the addition of free abrasives to the polishing solution enables the smaller-particle-size free abrasives to remove trace amounts of scratch edge material, resulting in a reduction in the size of the scratch on the surface of the workpiece and reducing the surface Ra of the polished workpiece. At the same time, free-abrasive trace material removal improves the MRR of harder workpieces (an approximately 8% increase). However, for less hard workpieces, the free abrasive causes the load Fw on the consolidated abrasive to decrease, which in turn reduces the depth of cut hw of the consolidated abrasive and has an inhibiting effect on the polishing MRR (an approximately 27% decrease). According to the workpiece-abrasive-polishing-pad contact model of the polishing process, the surface microstructure of the polishing pad mainly affects the effective contact area Ap and the effective number of abrasive grains Ns in the polishing process. The surface hardness of the polishing pad and the hardness of the workpiece mainly affect the indentation depth hp of the abrasive in the polishing pad and the cutting depth hw of the abrasive in the polishing process. Small amounts of free-abrasive removal can improve the quality of the polished surface, but the mechanism of the effect on MRR is different for different hardness values. A comprehensive analysis of the surface microstructure of the polishing pads, surface hardness, and abrasive state on the surface material removal mechanism of the workpiece provides a theoretical basis for the selection of polishing pads for the polishing of different workpieces.