通过CCD摄像机对保护箱中的同轴送Nb,Ti,Al混合金属粉的喷嘴出口的粉末汇聚情况和沉积过程的熔池形貌进行了实时观察与分析。根据微粒光散射理论对CCD拍摄的粉末流图像进行分析,得出了不同位置处粉末流的分布模型,并结合实验获取了用于激光沉积的同轴送粉喷嘴到沉积表面的适用距离区间。通过图像处理程序对熔池形貌进行提取,分析了工艺参量对熔池形貌的影响;对多层沉积过程中沉积层的熔池形貌特征、熔池波动现象等进行了较详细的分析探讨。通过系统的观测与分析,深入理解粉末流的汇聚与熔池的实时变动行为,有利于更好地控制激光沉积过程。

The behaviors of the Nb,Ti,Al mixed powder stream concentration from a coaxial laser deposition nozzle and the molten pool in laser deposition process in the controlled environment chamber have been observed and analyzed with a charge coupled device (CCD) camera. The distributed modes of powder stream at different positions were analyzed based on the theory of the scattering of light by small particles, and the available distance for laser deposition from the nozzle to the deposited substrate was obtained by combining with the experiments. The molten pool characteristics were gained using image processing programs and the effects of processing parameters on the shape of the molten pool were found out. The dynamic characteristics of the molten pool and the phenomenon of oscillation during multi-layer deposition were also discussed. The systemic studies on the behaviors of powder stream concentration and molten pool help to understand and control laser deposition processing better.