A low-temperature high-speed flame spray gun

Abstract

The invention discloses a low-temperature high-speed flame spraying gun. A combustion chamber is installed in the outer gun body. The outer gun body head installs the gun barrel body through the intermediate connecting body. The powder feeding nozzle is installed on the intermediate connecting body. The entrance of the combustion chamber is sealed by a head cover of the combustion chamber, a central cone is arranged through the head cover of the combustion chamber, and a fuel nozzle is sheathed outside the central cone. A trumpet-shaped annular oxygen / fuel channel is formed between the fuel nozzle and the center cone body, and an annular primary nitrogen mixing straight channel is formed between the center cone head and the head cover of the combustion chamber. There is a spark plug on the combustion chamber head cover. The outer gun body tail cover is installed at the outer gun body tail. An oxygen inlet joint communicated with the oxygen / fuel passage is installed on the tail cover of the outer gun body. A fuel injection joint communicating with the oxygen / fuel passage is installed on the combustion chamber head cover. A nitrogen inlet joint communicated with the primary nitrogen mixing straight passage and the secondary nitrogen injection eccentric hole is installed on the outer gun body. The invention can obtain a high flame flow velocity, and can make the flame flow temperature within a reasonable low temperature range and be greatly adjustable.

Description

technical field [0001] The invention relates to a low-temperature high-speed flame spraying gun, which belongs to the technical field of high-speed flame spraying. Background technique [0002] High-velocity flame spraying is to use the high-temperature and high-speed combustion gas generated by the combustion of gas or liquid fuel and high-pressure oxygen or air to heat the spray material (wire or powder) (to a molten or semi-molten state) and accelerate (to a supersonic state), and spray it into A thermal spraying process that forms a coating on the surface of a workpiece. It was first launched by the Browning Engineering company of the United States in the early 1980s. It has experienced more than 30 years of development and is widely used in the preparation of various surface coatings. [0003] High-velocity oxygen-fuel supersonic flame spraying (HVOF) in high-velocity flame spraying has extremely high flame velocity (maximum particle velocity can reach 1000m / s or even ...

AI Technical Summary

Problems solved by technology

However, it can be found from actual implementation that HVOF has the following defects: HVOF changes the speed and temperature of combustion gas by adjusting the mass flow ratio (or oxygen-fuel ratio) of oxygen and fuel during spraying, but the process window is usually narrow, and oxygen The adjustable range of the fuel ratio is small, and the lower oxygen-fuel ratio is difficult to ensure the full combustion of the fuel, and even the formation of combustion products that are not conducive to the quality of the coating will occur; while the higher oxygen-fuel ratio can ensure the full combustion of the fuel to a certain extent, However, more active oxygen remaining in the combustion gas will cause serious oxidation of the coating material, especially when spraying metal and its composite materials, the coating material is easy to oxidize, and the coating deposition quality is poor; at the same time, the higher deposition temperature is easy It leads to residual tensile stress in the coating structure, which is not conducive to the improvement of the coating's bonding strength, fatigue resistance, wear resistance, and stress corrosion resistance.

The deposition speed of spray powder in cold spraying needs to be higher than its critical speed to complete reliable deposition, so cold spraying has high requirements on materials, not all metal materials are suitable for cold spraying, and cold spraying has requirements on the type and pressure of gas The conversion efficiency of electric energy to gas heat energy is limited, and the energy consumption of the gas heating device is relatively high, so the preparation cost also increases accordingly

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