How it works: The liquid, such as kerosene, that enters the combustion chamber from a small hole is burned. After being atomized and mixed with oxygen, it is ignited, and a strong gas-phase reaction occurs. The heat released by the combustion can cause the product to expand violently. The expanding gas flows through the Laval nozzle. Constraints on the formation of high temperature flame flow in supersonic spraying. Flame heating accelerates the sprayed material to reach the surface of the substrate, forming a high-quality coating
Supersonic spraying is a high-temperature, high-speed combustion flame flow produced by the combustion of propane, propylene and other hydrocarbon gases or hydrogen and high-pressure oxygen in a combustion chamber or special nozzle. The combustion flame velocity can reach Mach 5 (1500m/s). )above. Commonly referred to as HVOF (High Velocity Oxygen Fuel). The powder is fed axially into the flame, the ejected particles can be heated to a molten or semi-molten state, and accelerated to a speed of up to 300-500m/s or even higher, resulting in high bond strength and compactness of high-quality coatings. .Supersonic flame speed is high, but the temperature is relatively low. For WC-Co cemented carbide, the decomposition of WC can be effectively suppressed during the spraying process. The coating not only has high bonding strength, but also is dense and has excellent wear resistance. Its wear resistance greatly exceeds that of plasma sprayed coatings, which is equivalent to explosive sprayed coatings, and also exceeds that of electroplated hard chrome coatings and sprayed fusion coatings. Its use is extremely widespread.
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