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在同轴送粉激光熔覆过程中,粉末流是影响熔覆质量的重要因素。为了提高粉末流的汇聚性,考察粉末性质对粉末流场的影响,建立了同轴送粉激光熔覆粉末流数值模型。模拟计算了NiCoCrAlY、ZrO2、W三种典型粉末的粉末流形貌,并进行了粉末流的验证实验,实验结果与计算结果趋势吻合,说明模型具备合理性与可靠性。基于该模型,深入研究了粉末粒径、形状、密度和碰撞弹性恢复系数对粉末流汇聚的影响规律,在特定送粉工艺参数下,在粉末粒径增大时,汇聚焦距减小,汇聚浓度在一定粒径范围内达到最大值;在粉末形状系数或者密度增大时,汇聚焦距减小、汇聚浓度增大;在粉末颗粒的恢复系数减小时,汇聚焦距与汇聚浓度都增大。
In the coaxial powder coating laser cladding process, powder flow is an important factor affecting the quality of the cladding. In order to improve the convergence of the powder flow and examine the influence of the powder properties on the flow field of the powder, a numerical model of the powder flow in the coaxial powder feeding laser cladding was established. The powder flow morphology of NiCoCrAlY, ZrO2, W powders was simulated and simulated. The experimental verification of the powder flow was carried out. The experimental results agree well with the calculated results, which shows that the model is reasonable and reliable. Based on this model, the effects of particle size, shape, density and elastic recovery coefficient on the convergence of powder flow were studied in detail. Under specific powder feeding parameters, as the particle size increases, the focal length decreases and the concentration And reach the maximum within a certain range of particle size. When the powder shape factor or density increases, the focal length decreases and the concentration increases. When the recovery coefficient of powder particles decreases, the focal length and convergence concentration increase.