摘要
使用金刚石平磨盘对聚晶金刚石(polycrystalline diamond,PCD)复合片的金刚石层进行高速研磨实验,研究研磨压力对PCD研磨去除率、表面粗糙度和表面形貌的影响.结果表明:当研磨压力为 0.10～0.18 MPa时,随着研磨压力的增大,PCD的研磨去除率增大,表面粗糙度减小.PCD研磨表面缺陷主要包括沿晶破碎、微小凹坑、机械划痕、微裂纹等,且随着研磨压力增大,研磨表面平滑面积扩大,机械划痕变小.
Abstract
Objectives:Polycrystalline diamond(PCD),as a superhard material with high hardness,high wear resist-ance,and good impact toughness,has a wide range of applications in fields such as cutting tools for superhard materials.However,due to its high hardness,the precision surface processing of PCD has always been a technical challenge.This paper aims to study the influence of lapping pressure on the surface quality of PCD,particularly focusing on the materi-al removal rate,surface roughness,and changes in surface morphology under high-speed grinding conditions.Methods:The experiment adopts a single-factor test method,keeping the abrasive particle size W5 of the diamond flat grinding disc and the lapping speed of 43.3 m/s constant,while varying the lapping pressure(from 0.10 MPa to 0.18 MPa)to study its impact on the material removal rate,the surface roughness,and the surface morphology of polycrystalline dia-mond material.The experimental material is a ϕ13 mm×2 mm polycrystalline diamond composite sheet with a dia-mond layer thickness of approximately 1 mm.The experimental apparatus is a high-speed grinding testing machine,which uses an electric spindle to drive the diamond flat grinding disc,with a lapping time of 20 minutes.The lapping process is conducted without the use of coolant to avoid its influence on the experimental results.Results:The experi-mental results indicate that the lapping pressure has a significant impact on the material removal rate of PCD.As the lapping pressure increases from 0.10 MPa to 0.18 MPa,the lapping removal rate increases from 0.005 mg/min to 0.030 mg/min,indicating that an increase in lapping pressure significantly improves material removal efficiency.The influ-ence of lapping pressure on the surface roughness of PCD is also significant.With an increase in lapping pressure,the surface roughness gradually decreases,reducing from a higher value at 0.10 MPa to a lower value at 0.18 MPa,with a roughness Ra reduction of approximately 0.020 μm.The impact of lapping pressure on the surface morphology of PCD is manifested by a reduction in surface defects and an expansion of smooth areas.At lower lapping pressures,the sur-face exhibits numerous pits,interstitial cracks,and mechanical scratches.As the lapping pressure increases,the number of these defects gradually decrease,and smooth areas gradually expand.Scanning electron microscope observations re-veal that an increase in grinding pressure helps reduce defects such as intergranular fractures,minute pits,and mechanic-al scratches,resulting in a smoother surface.Conclusions:This paper experimentally studies the influence of lapping pressure on the material removal rate,surface roughness,and surface morphology of PCD,and draws the following con-clusions.The lapping removal rate of PCD material significantly increases with an increase in lapping pressure,primar-ily attributed to the high-frequency collisions and frictional heat between diamond abrasive particles and PCD during the lapping process.An increase in lapping pressure significantly reduces the surface roughness of PCD,primarily benefit-ing from the decreased cutting depth of abrasive particles and increased actual contact area caused by the increased lap-ping pressure,and the promotion of surface thermochemical reactions and mechanical thermal removal effects by fric-tional heat.An increase in lapping pressure leads to a reduction in surface defects,an expansion of smooth areas,smal-ler mechanical scratches,and a significant improvement in the surface quality of PCD.
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