脉冲敲击技术对PI微球表面粗糙度的影响

作为点火靶重要候选靶丸之一, 聚酰亚胺 (PI) 空心微球采用降解芯轴技术结合双单体气相沉积聚合法 (VDP) 制备. 在PI涂层过程中微球碰撞对表面质量影响较大, 为了减小碰撞提高表面质量, 选用筛网盘做样品盘, 激励方式由压电振动模式改为脉冲敲击模式进行对比. 实验数据表明微球运动过程中碰撞是引起表面质量变差的原因, 通过理论分析确认了筛网盘通过减少接触点可以减少微球与微球间、微球与样品盘间的碰撞, 并且将压电振动改为脉冲敲击模式可以减小微球碰撞次数. 脉冲敲击模式与压电振动模式相比, 其可控性、微球弹跳幅度、消除静电等方面均优于压电振动. 对于微球壁厚均匀性而言, 压电振动略好于脉冲敲击, 但相差较小. 单个微球的壁厚最大偏差前者为0.68 μm, 优于后者的0.73 μm; 单个微球壁厚平均值在同一批次内的最大起伏, 前者为0.26 μm, 优于后者0.57 μm. 白光干涉仪数据显示脉冲敲击起到了提高微球表面质量的作用, 其表面粗糙度Rq值由52–93 nm 减小到28–44 nm. 关键词： 脉冲敲击技术 聚酰亚胺靶丸 表面粗糙度 壁厚均匀性

Influence of pulse tapping technology on surface roughness of polyimide capsule

As one of the most important ignition capsules, the polyimide capsule was prepared by depolymerizable mandrels technique combined with vapor deposition polymerization method. Instead of the plane pan and piezoelectric vibration model, the mesh pan and pulse tapping was selected to reduce microsphere collision so that surface quality was improved in polyimide fabrication. Experimentsal and theoretical results show that the capsule surface becomes more rough because of collisions between microspheres and the pan. The mesh pan could reduce microsphere collisions, which was also reduced by changing piezoelectric vibration into pulse tapping. As a result, root-mean-square value ranges from 52–93 nm to 28–44 nm. There are many advantages with pulse tapping model, such as better controllability,lower bounce rate and less static; however piezoelectric vibration model is slightly better than the pulse taping in wall thickness uniformity. Measurements of single microsphere show that the deviation of the former is 0.68 μ which is better than that of the latter (0.73 μm). For the average value of microspheres in the same batch, the former has a value 0.26 μ which also is better than the latter (0.57 μm).
Keywords： pulse tapping technology polyimide capsule surface roughness wall thickness uniformity