hvof

Supersonic flame spraying is a high-temperature and high-speed combustion flame flow formed by the combustion of hydrocarbon gases such as propane and high oxygen in an incineration chamber or specialized nozzle. The combustion flame flow rate is 5 Mach (1500 meters/second). Supersonic flames have high velocity but low temperature.

Supersonic flame spraying is a new type of thermal spraying technology invented by Braun in the United States in 1981. The core of high-speed flame spraying (HVOF) equipment is the spray gun, which consists of three parts: the combustion chamber (which can fully heat and accelerate the spraying material particles), the Laval nozzle (which can accelerate the flame flow to supersonic speed), and the equal cross-sectional length nozzle (which can fully heat and accelerate the spraying material particles).

For tungsten carbide cobalt hard alloys, the decomposition of tungsten carbide during the spraying process can be effectively controlled. 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 spray coatings, equivalent to explosive spray coatings, as well as electroplated hard chromium layers and spray melted layers. Widely used.

Before the flame spraying process, it is necessary to understand the actual situation and technical requirements of the sprayed workpiece, and then analyze and determine the coating thickness. Generally speaking, it must be processed after flame spraying, so the coating thickness should maintain a machining allowance and also consider thermal expansion and contraction during spraying. Measurement of coating materials. The selection criteria are that the coating material should meet the material, matching requirements, technical requirements, and working conditions of the sprayed workpiece.

Select the materials for the bonding layer and working layer to determine the parameters: pressure, powder particle size, and corresponding motion speed in the component. Supersonic flame spraying has low oxygen content, suitable temperature, and high flame rate, which can effectively prevent the oxidation and decomposition of powder coatings. Therefore, it is particularly suitable for spraying high wear-resistant carbonized coatings.