flame spraying

By the flame spraying Various surfaces can be processed in a targeted manner and thus protected against corrosion and wear. Different layer thicknesses and surface topologies can be produced by flame spraying. In flame spraying, a powder or wire-like spray additive is melted in a fuel gas-oxygen flame and thrown onto the pre-treated surface of the respective material with the help of the combustion gases and an atomizing gas.

Flame spraying uses metallic or ceramic flame spraying materials that are in the form of wire or powder. In connection with coatings, flame spraying is primarily used to structure the substrate and to improve hardness and wear resistance.

Flame spraying with wire 

In flame spraying with wire, two metallic wires of the same composition are polarized in opposite directions by applying an electrical DC voltage and fed through the contact nozzle at exactly the same speed using a feed motor. Due to the opposite polarity, touching the wires during flame spraying creates an electric arc that melts the wires.

The melted wires are atomized into particles using compressed air and thrown onto the workpiece, where they then solidify and form a rough layer of flame.

During flame spraying with powder, combustible gases such as acetylene, propane or hydrogen and oxygen are mixed in specific ratios. They flow through a nozzle, are ignited and form a flame, in the center of which the coating material is continuously fed as a powder.

The powder particles are melted in the flame, which can be up to 3200°C depending on the fuel gas composition, and thrown onto the surface of the workpiece. There they solidify and form a coating on the surface. Compressed air can be fed in at different pressures through an air cap surrounding the nozzle, which can be used to achieve different roughness levels during flame spraying.

Metals, ceramics, carbides or mixtures can be used as spraying materials for film spraying.

Rhenotherm GmbH is the exclusive licensee for Plasma Coatings Inc. in Germany and carries out flame spraying as a contract coater.