Preparation method of nano-metal coating powder

Abstract

The invention discloses a preparation method of nano-metal coating powder. The preparation method comprises the following steps that preparation of nano-core particles and preparation of the nano-metal coating powder are performed continuously, specifically, core raw materials are heated and evaporated by adopting a core particle preparation device; core raw material steam is cooled into solid nano-core particles through airflow of a working medium gas circulation system, the solid nano-core particles are conveyed to a coating device, and the nano-core particles are in a dispersed state in a nano-core particle conveying pipeline; and metal steam of a metal coating material and the nano-core particles meet in a hollow circular truncated cone-shaped coating tank with a large upper part and a small lower part, and the surfaces of the nano-core particles are uniformly and completely deposited to form a metal coating layer in the spiral descending and shrinking process, and after the metal coating layer enters a solidification tank along with air flow to be solidified, a compact metal coating layer is formed on the surfaces of the nano-core particles. In the conveying and coating process, the core particles are good in dispersity, and uniform deposition and complete coating of the coating powder on the nano-core particles can be achieved.

Description

technical field [0001] The invention relates to the technical field of metal-coated powders, in particular to a preparation method of nanometer metal-coated powders. Background technique [0002] The metal-coated powder in the prior art is mainly prepared by chemical coating method, the process is relatively cumbersome, or the coating is relatively difficult, or causes pollution, so the industrial application is relatively limited. [0003] Although the physical vapor deposition method in the prior art can realize the deposition of nanoparticles on a plane, it usually needs to be carried out in a vacuum environment, and the entire metal-coated powder preparation process needs to be vacuumed all the time, which increases the production cost. [0004] A method of preparing coated powder is disclosed on the Chinese patent website. This method uses plasma as a heat source to heat, melt or vaporize the coating material, and the coating material meets the core particles to finally...

AI Technical Summary

Problems solved by technology

However, when this method prepares metal-coated powder, the prepared core particles stored in the container are used to transport the powder to the coating tank by means of vibration powder feeding or carrier gas powder feeding. It is easy to agglomerate, the smaller the particle size, the more severe the agglomeration, so the particle size of the core particles should not be too small, not submicron, let alone nanometer, because submicron particles or nanoparticles, using carrier gas It is difficult to send submicron particles or nanoparticles that meet the quality requirements to the coating tank smoothly by means of vibration or vibration, and it is easy to block or the powder sent is agglomerated powder

That is, the use of this device to prepare metal-coated powders greatly limits the size of core particles, and it cannot be smoothly transported for submicron particles or even nano-sized particles that are easily agglomerated. Therefore, this device is only suitable for micron-sized core particles. Particles are coated, and it is not possible to coat submicron particles or even nano-sized particles

[0005] In addition, 1, because the coating tank or the reactor in the preparation device adopted by this method is a straight cylinder, the contact between the coated powder particles after melting or gasification and the core particles meets in a straight line, and the transportation of the two The distances are short, so that the contact time between the core particles and the coating powder particles is short, and it is difficult to form an effective and complete coating.

2. Since there is only one plasma gun or plasma atomization spray gun system connected with water and electricity, the plasma flame moment, atomization nozzle and central axis of the reactor in the plasma atomization spray gun system are all on the same straight line, In addition, the axis of the powder feeding channel of the coated powder is also on the same straight line as the plasma flame moment and the axis of the atomizing nozzle. In order to ensure the safety and normal use of the plasma atomizing spray gun system, the current and The power and energy are relatively insufficient, and the evaporation effect of the coated powder is difficult to guarantee

3. Since the atomizing nozzle in the plasma atomization spray gun system is located under the plasma torch and coating materials such as the outlet of the coating powder feeding channel, the high temperature of the plasma torch and the molten state or gasification of the coating powder In this state, the atomizing nozzle may be ablated and damaged so that it cannot work normally. The high-speed jet sprayed by the atomizing nozzle may cause the pressure in the nozzle to rise rapidly, which will affect the stability of the plasma torch, and may cause it to extinguish or even return to flame. Ablative plasma atomizing spray gun

4. The position, angle and quantity of the powder inlet of the core powder are insufficient, and it is difficult to ensure that the core powder enters the coating tank uniformly, tangentially, and rotated, which affects the coating efficiency and coating quality

[0006] To sum up, in the prior art, the method of using plasma as a heat source to coat powder is difficult to achieve uniform deposition and complete coating of coated powder on the coated nano-powder, that is, nano-scale particles. The difficulty is that nano-powders are prone to agglomeration, it is difficult to disperse in space, the evaporation effect of the coating material is not good, the contact time between the coating powder particles and the core particles is short, and the coating material is completely intact on the surface of a single powder. Difficult to deposit

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