摘要
利用剪切增稠抛光技术(Shear-thickening polishing,STP)对Si_3N_4陶瓷圆柱工件进行的超精密加工,考察所制备的含有金刚石磨粒的抛光液流变行为,分析Si_3N_4陶瓷的金刚石基剪切增稠抛光液的STP特性,研究Si_3N_4陶瓷圆柱工件的加工效率、表面质量及圆度误差精度。结果表明:含有金刚石磨粒的抛光液具有非牛顿幂律流体的剪切增稠性质,当剪切速率(g(5))不断提高时,储能模量(G′)、耗能模量(G″)均呈现出一定的增长趋势,耗散因子(n′)不断降低;Si_3N_4陶瓷的STP加工为持续微切屑"柔性抛光"过程;抛光液中的金刚石磨粒粒径为0.2μm时,工件抛光的材料去除率相对较大,且MRR理论值与试验值的平均误差约为11.7%,表明在抛光区域内STP材料去除模型具有一定的有效性;工件经60 min的STP后,材料去除率由初期4.20μm/h下降到4.00μm/h,表面粗糙度R_a由107.2 nm降至26.5 nm;抛光120 min后,材料去除率会减小至3.85μm/h,表面粗糙度可降至R_a 6.5 nm;由初始圆度误差RONt 1.418mm下降至RONt 0.360mm,实现了Si_3N_4圆柱高效超精密抛光。
Shear-thickening polishing （STP） technology is used on ultraprecision machining of Si3N4 ceramics cylindrical workpiece. The STP slurry with diamond abrasives is prepared for STP process and its rheological property is studied. The polishing performance of Si3N4 ceramics with STP is analyzed. The machining efficiency, surface quality and roundness error of Si3N4 ceramic cylindrical workpiece are studied. Results show that STP slurry with diamond abrasives exhibits non-Newtonian power-law fluid characteristics with shear-thickening effect. When the shear rate （ γ ） increases, the storage modulus （G′） and loss modulus （G＂） show a growth trend. In addition, the dissipation factor （n′） decreases continuously. The STP removal characteristic of Si3N4 ceramics is a continuous micro cutting process of ＂flexible polishing＂. As using STP slurry with abrasive particle size of 0.2 μm, the difference of material removal rate （MRR） between theoretical and experimental results is 6.12%, and the validation of MRR model is verified. The MRR decreases from 4.20 μm/h to 4.00μm/h after 60 mins; polishing and the average surface roughness Ra reduces from 107.2 nm to 26.5 nm; and after 120 mins polishing, the MRR decreases to 3.85μm/h and Ra can be reduced to 6.5 nm; under the same conditions, the STP with diamond abrasives slurry can obtain the Si3N4 ceramics cylindrical workpiece with roundness error reduced from RONt 1.418 μm to RONt 0.360 μm, which indicates that STP process achieves the ultraprecision polishing of Si3N4 ceramics cylindrical workpiece.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2017年第9期193-200,共8页
Journal of Mechanical Engineering
基金
国家自然科学基金(51605163
51175166)
浙江省自然科学基金杰出青年基金(LR17E0500002)
湖南科技大学博士科研启动基金(E56121)资助项目
关键词
抛光
剪切增稠抛光
氮化硅陶瓷
金刚石磨粒
流变行为
表面粗糙度
圆度误差
高效加工
polishing
shear-thickening polishing（STP）
silicon nitride
diamond abrasive
rheology
surface roughness
roundnesserror
high-efficiency machining
