What is Powder Flame Spray ?
What is Powder Flame Spray
The powder flame spray process is similar to the combustion wire spray process with the difference, that powder and not a wire is injected into the flame. In the flame powder process, powdered feedstock materials are melted or semi-melted into the oxyfuel flame by heat of combustion and the particles/droplets are accelerated towards the substrate surface by the expanding gas flow and air jets. A powder feed carrier gas transports the powder particles into the combustion flame, and the gases transport the material towards the prepared workpiece surface. Typical choices for fuel gases are acetylene or hydrogen.
Here feedstock powders are introduced axially through the rear of the nozzle into the flame at the nozzle exit. This offers a much wider range of coating material options than the wire flame spray process.
Particle speed is relatively low (<100 m/s), and bond strength of the deposits is generally lower than the higher velocity processes. Porosity can be high and cohesive strength is also generally lower. Spray rates are usually in the 0.5 to 9 kg/h (1 to 20 lb/h) range for all but the lower melting point materials, which spray at significantly higher rates. Substrate surface temperatures can run quite high because of flame impingement.
About our Powder Flame Spray Equipment
Powder is fed into our spray torches in one of two ways which are by carrier gases or by gravity.
Gravity-fed devices have powder canisters or bottles mounted directly to, and on top of, the torch as in our 5PM-II Powder Flame Spray Gun . Powder feed rate is controlled by a pinch valve that meters powder into the body of the torch, where it is aspirated by the gases flowing through the torch.
Carrier-gas-fed units use externally mounted powder feeders as in our 6PM-II Powder Flame Spray Gun . Powder feeders, use a carrier gas stream to transport the powder from the feeder through a hose to the spray torch. Carrier gases used for flame spray are commonly air or nitrogen.