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本文从理论推导、流体力学仿真、喷雾粒径检测分析以及支架喷涂试验四个方面研究超声波喷涂技术并成功应用于血管支架喷涂工艺的优化.首先基于超声波雾化物理模型推导建立超声雾化粒径方程,其次利用计算流体动力学模拟超声雾化微观过程,定义超声雾化过程的三种雾化模式:亚雾化模式、理想雾化模式以及射流雾化模式,并建立了超声雾化临界振幅方程以及理想雾化模式下的雾化体积和功率方程.然后设计超声喷雾粒径检测实验,研究功率、气体压力、表面张力等工艺参数对雾化粒径的影响,结果表明超声波喷雾运动过程中少量粒子碰撞合并,但喷雾质量总体稳定,粒径尺寸在10m左右.在粒径尺寸分布方面,利用Rosin-Rammler分布拟合超声喷雾粒径均匀度指数在7.11～11.48之间,相比传统喷雾技术雾化均匀性、可控性大大提高.最后,在上述研究基础上制定血管支架超声喷涂工艺参数并进行了优化,消除了常见的血管支架涂层表面各种缺陷,为制备性能优良的血管支架表面涂层提供了理论和技术支撑.
In this paper, ultrasonic spray technology is studied from four aspects of theoretical derivation, fluid mechanics simulation, spray particle size analysis and stent spray test, and it is successfully applied to the optimization of the spray coating technology of vascular stent.Firstly, based on the ultrasonic atomization physical model, Equations, secondly, using computational fluid dynamics to simulate the micro-process of ultrasonic atomization, three kinds of atomization modes of ultrasonic atomization are defined: sub-atomization mode, ideal atomization mode and jet atomization mode, and the ultrasonic atomization critical amplitude Equation and the atomization volume and power equation in the ideal atomization mode.And then the ultrasonic particle size detection experiment is designed to study the influence of the process parameters such as power, gas pressure and surface tension on the atomization particle size.The results show that during the ultrasonic spray movement In the particle size distribution, the uniformity index of the spray particle size using the Rosin-Rammler distribution was between 7.11 and 11.48. Compared with the traditional spray Technical atomization uniformity, controllability greatly increased.Finally, based on the above study to develop vascular branch Ultrasonic spray process parameters and optimized, eliminating the common defects of the surface of the stent layer, providing a theoretical and technical support for the preparation of excellent performance of the vascular stent surface coating.