Spraying particle protection method and supersonic spray gun

Abstract

The invention belongs to the technical field of surface engineering thermal spraying, and relates to a spraying particle protection method and a supersonic spray gun. The spray gun comprises a powder injection pipe, and a hydrogen inlet is formed in the powder injection pipe; a mixture of particles to be sprayed, particle carrier gas and hydrogen is jointly fed into a spray gun flow field, combustion gas and fuel are fed into a spray gun, and the combustion gas is excessive than the fuel; in the combustion process, the combustion flame of the hydrogen is stretched to be in a hollow film shape, the combustion power generated by combustion of the hollow film is very small, the carrier gas is not obviously heated, but radial expansion waves generated by combustion of the hydrogen prevent radial convection between the high-temperature main gas and the carrier gas; meanwhile, gaseous water of combustion products of hydrogen and oxygen can play a role of a heat insulation layer; the problems that the adiabatic shear effect is reduced and the particles are radially dispersed or oxidized in the overheat or heat exchange process of the sprayed particles are solved.

Description

technical field [0001] The invention belongs to the technical field of surface engineering thermal spraying, and relates to a spraying particle protection method and a supersonic spray gun. Background technique [0002] Existing thermal spraying generally forms a coating by impacting particles on the substrate through airflow acceleration. In order to achieve rapid acceleration of the airflow, the airflow generally needs to have a higher temperature. For example, according to the published content of the patent "a spray gun for generating supersonic airflow", fuel (such as propane) and compressed air are used to generate high temperature during spraying, thereby realizing supersonic gas jet flow. The temperature of the gas flow generated by the combustion reaction (hereinafter referred to as the main gas) is too high, which can easily cause the particles to overheat, even melt or gasify, resulting in a smaller "adiabatic shear" effect when the particles collide with the subs...

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