Design Of Atomizing Nozzle For Laser Cladding Alloy Powder And Experimental Research

Laser cladding is a new type of material processing and surface modification technology. As one of the major directions of laser cladding, cladding material attracted lots of attention. Currently, Fe, Ni, Co-based alloy powders are widely used in laser cladding, besides material ratio and systems, material particle size range and mobility are also critical in laser cladding. Most of alloy powders are produced by gas atomization, and the spray nozzle is the core component of a gas atomization device, so it’s a key project to design a spray nozzle with simple structure and high efficiency which can be used to produce alloy powders for laser cladding.As to the low efficiency and low degree of sphericility with frequently impeded in atomizing process of traditional gas-atomizing nozzle, a new nozzle with Laval outlet accompanied by ventilation hole and guiding pipe was designed to prepare spherical alloy powders for laser cladding in the paper. The gas velocity at the outlet of nozzle was simulated by FLUENT, and the air pressure on the nozzle centerline was tested by u-shaped water pressure gauge. After the atomization experiments, the powders achieved were analyzed by SEM and Hall flowmeter, and the alloy powders were used in laser cladding experiment. They conclusions can be obtained as followed:1. Compared with the traditional nozzle, the designed nozzle can generate supersonic flow around the outlet. Because of the anti-sticking ring and ventilation hole, the process of atomization is unimpeded and security.2. With the pipe length of30mm, the designed nozzle can achieve the best performance. Compared with the traditional nozzle, the atomization efficiency is increased by3times. The alloy powders produced by designed nozzle have better sphericity, mobility and loss density. The alloy powders mobility is reduced from24.3s/50g to17.2s/50g, the loss density is increased from3.91g/cm3to4.25g/cm3.3. Laser cladding alloy power experiment was carried on45steel matrix. The results show that the microstructure of cladding layer is fine and uniform, and there are no cracks, holes and other defects.The powder can meet the requirements of laser cladding.