应用脉冲式Nd：YAG激光焊接心脏辅助装置

Third-Generation Left Ventricular Assist Device in Pulsed Nd：YAG Laser Welding

左心室辅助装置（LVAD）被成功应用于心脏移植过渡治疗方法，缓解末期心脏病人的痛苦。Ti6A14V合金由于其优越的抗腐蚀性及生物适应性被作为LVAD叶轮外永久性密封包装的材料。由于受到整体装置尺寸及重量的限制，材料厚度仅为0．5～0.7mm。激光焊接技术由于其较高的束流质量、较低的热量输入和较大的熔深熔宽比，最终被用作该材料最后的密封焊接工艺。主要介绍脉冲式掺钕钇铝石榴石（Nd：YAG）激光焊接技术在国外先进的第三代某品牌左心室心脏辅助装置密封焊接中的应用与研究。实验结果表明，经焊接工艺实验最终选定的主要激光焊接工艺参数如下：峰值功率414W，焊接速度360mm·min-1，覆盖率70％。焊接接头沿焊缝方向均一稳定，焊缝成型良好，热影响区窄，焊接接头焊缝与原始母材的力学性能差别不大，未发现气孔、夹杂及裂纹等缺陷。

Left ventricular assist device （LVAD） is a successful and useful treatment method for end-stage heart failure. An important part-hydrodynamically suspended impeller exposed to corrosive conditions, is required to be sealed hermetically into micro packages. Laser beam welded Ti6AI4V alloy is adopted in anti-corrosion micro packages for the LVAD impeller. Thin and narrow welds are required for such medical equipments. Pulsed Nd： YAG welding is successfully adopted as sealing method for the impeller. The experimental results show that peak power of 414 W, welding speed of 360 mm · min -1, and overlap of 70% are the final selection of the main laser welding process parameters. Welded joints along the direction of welding line are uniform and stable, the welding line is good, and the heat-affected zone is narrow. There is little difference between welded joints and base metal in terms of mechanical properties. Porositv, inclusions, cracks and other defects are nnt found.