送粉式激光熔覆获得最佳熔覆层的必要条件及其影响因素

在分析自动送粉式激光熔覆过程中熔覆材料颗粒加入方式及其在激光束中的行为的基础上，建立热平衡方程，推导出反映熔覆过程实际情况的参数：熔覆材料颗粒尺寸、在激光束中运动距离、加热温度、激光功率密度之间的相互关系式等。指出在自动送粉式激光熔覆中能够获得最佳熔覆层的必要条件是：熔覆材料颗粒进入激光束后直到其落到基体材料表面之前，必须始终在激光束中。激光束沿着扫描方向必须有足够的宽度是满足上述条件的关键，同时提出其计算方法及公式，并阐明获得最佳熔覆层的工艺参数之间的匹配原则

Conditions and Factors for Obtaining Optimum Coatings in the Laser Coating Process by a Powder Feeding Method

On the basis of an analysis on the feeding pattern of the coating material and its behavior in the laser beam during the process of laser coating with automatic powder feeding, a heat equilibrium equation was established and expressions relating the parameters in the process were obtained. The parameters include the grain size of the coating material, its distance of motion in the beam, heating temperature and power density. It is pointed out that the necessary condition for obtaining optimum coating in the process with automatic powder feeding is that from the instant of the powder grains entering the laser beam to the instant that the grains reach the substrate surface, the powder grains must be persistently within the laser beam to fulfill the above condition. The laser beam must have enough width along the scanning direction, and this width can be calculated by the expression suggested in this paper. Finally, the principle for matching the process parameters to obtain an optimum coating is presented.