Conical powder feeding device for ultra-high-speed plasma cladding and ultra-high-speed plasma cladding method

Abstract

The invention provides a conical powder feeding device for ultra-high-speed plasma cladding and an ultra-high-speed plasma cladding method. The conical powder feeding device comprises a central cylinder, a water-cooled inner spacer, a powder guide spacer, and a protective air spacer and a water-cooled outer spacer which are assembled to the outside from a central shaft. The entrance of the centralcylinder is axially connected with the anode of a cladding gun of a plasma cladding system; the conical powder feeding device delivers the powder to a plasma jet uniformly at a high speed, under themechanical constraint of the outlet oblique conical surface of the powder guide space, a conical powder fluid with a pre-designed angle is formed, and finally the fluid focuses on the central shaft, so as to obtain the powder jet with high concentration, high speed, uniform distribution and small divergence, and under the ultra-high-speed plasma cladding condition of above 10-200m / min relative movement speed of the plasma cladding system and a workpiece, a cladding layer with thin thickness, uniform chemical composition, low surface roughness, low dilution rate and dense microstructure can beobtained.

Description

technical field [0001] The invention relates to the fields of plasma cladding, plasma spraying, remanufacturing and repair, and in particular to a conical powder feeding device for ultra-high-speed plasma cladding and an ultra-high-speed plasma cladding method, by focusing the powder material on the central axis , which is conducive to improving the uniformity and stability of powder heating and acceleration in the process of plasma cladding, plasma spraying, remanufacturing and repairing, and reasonably allocates the energy ratio between heating powder and heating workpiece substrate, so that in ultra-high-speed plasma melting Under the cladding conditions, a cladding layer with thin thickness, uniform chemical composition, low surface roughness, low dilution rate and dense microstructure can be obtained. Background technique [0002] Plasma cladding technology is a surface treatment technology that uses high-energy-density plasma jets to melt the fed powder or wire onto th...

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Problems solved by technology

[0005] (c) Compared with coatings prepared by electroplating and thermal spraying techniques, the surface roughness of the cladding layer is high, resulting in a large amount of follow-up processing on the surface of the workpiece after cladding, which not only greatly increases the cost of follow-up processing, but also reduced productivity

[0006] (d) Due to the use of a single powder feeding pipe or two symmetrical powder feeding pipes to feed the powder (cladding material) into the plasma jet from the side of the plasma jet, the powder beam is excessively concentrated on one or the other side of the plasma jet Two positions, the powder from the powder feeding pipe diverges to the edge and surroundings, making the trajectory of each powder particle different, resulting in a wide range of temperature and movement speed of each powder particle, and poor uniformity

[0007] (e) Most of the energy of the plasma arc is used to heat and melt the surface of the workpiece substrate instead of the powder, resulting in excessive melting of the substrate, wide heat-affected zone, and high dilution rate of the cladding layer, which greatly reduces the overall performance of the coating. Weaken the mechanical properties of the matrix

[0008] (f) Due to the divergence of the powder, the heating uniformity of the powder in the plasma arc is poor, and some powder deviates from the plasma jet area and cannot be heated and accelerated; some powder is overheated, resulting in element evaporation, excessive burning loss, and segregation of the cladding layer. The chemical composition is quite different from the original powder, which not only causes low powder utilization rate, but also pollutes the processing environment and affects the health of operators

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