A low-temperature spraying process for anti-cracking

Abstract

The invention discloses an anti-cracking low-temperature spraying process, which comprises the following steps: a material charging step, a preheating step, a spraying step, adjusting the air flow rate, and spraying liquid tungsten carbide on the metal surface; a curing step, and the completion. The invention adopts supersonic spraying equipment for spraying; by using nitrogen, hydrogen, argon as protective gas and powder feeding gas, the flame core temperature of the flame flow is controlled at 900-1000°C, the thermal stress of the coating is reduced to the minimum, and its powder The flying speed of the particles is fast, the spray distance is shortened to 130mm, the whole deposition process is less than 1 second, and there is almost no time for particle oxidation or deformation. The dislocation density in the sprayed coating is higher, and the hardness of the coating is slightly higher than that of the raw material. The thermal influence on the substrate is very small, the substrate does not produce a measurable heat-affected zone, no intermetallic compounds are produced, and the coating thickness reaches 1.5mm and is still uniform without cracks.

Description

technical field [0001] The invention relates to a low-temperature spraying technology, in particular to the improvement of the low-temperature anti-cracking spraying process for metal coating spraying. Background technique [0002] Due to the high thermal stress of the metal coating, high-temperature spraying is easy to crack. The existing metal spraying process uses special cold spraying equipment for spraying; the spraying speed is slow and the efficiency is low; traditional plasma spraying and HVOF supersonic spraying are due to flame flow The temperature is too high and the thermal stress is large. When spraying on substrates with large thermal deformation such as titanium, aluminum, and stainless steel, thermal stress cracks inevitably exist in the coating, and the thickness of the coating is limited, which seriously causes coating damage. Crack and fall off. Contents of the invention [0003] In order to overcome the deficiencies of the prior art, the present invent...

AI Technical Summary

Problems solved by technology

[0002] Due to the high thermal stress of the metal coating, high-temperature spraying is easy to crack. The existing metal spraying process uses special cold spraying equipment for spraying; the spraying speed is slow and the efficiency is low; traditional plasma spraying and HVOF supersonic spraying are due to flame flow The temperature is too high and the thermal stress is large. When spraying on substrates with large thermal deformation such as titanium, aluminum, and stainless steel, thermal stress cracks inevitably exist in the coating, and the thickness of the coating is limited, which seriously causes coating damage. cracking, falling off