Plasma spray coating is the most flexible process out of all the thermal spray processes. Basically, it is the spraying of molten or heat-softened material onto a surface to provide a coating. The utilization of the powerful plasma spray coating technology can facilitate the spraying of almost any ceramic, cermet or metal onto a wide variety of materials with exceptional bond strength as well as a minimal distortion of the substrate.
Plasma Spray Coating Process
The objective of plasma spray coating is to heat up and scatter material particles across the work surface with minimum waste and overspray. Before the HVOF system was invented, plasma guns were widely used for adding velocity to the material particles. Plasma arc, as the gun is named, was devised as an electrical appliance that could effectively replace the old flame spray machines.
These guns can heat up the particulates to a certain degree so that they can easily be deformed to be applied on the work surface. By connecting the poles of a power supply unit to an electrode and concentric nozzle, a plasma arc can be created. A high flow-rate inert gas (either the combination of nitrogen & hydrogen, or the combination of argon & hydrogen or helium) along the arc’s axis can be added to push the arc forward to the front of the plasma gun.
Next, we inject the powder (made from metals, ceramics or cermets) into the flaming plasma near the nozzle. The gas and powder arc expands rapidly and the resultant velocity pushes the hot powder particles forward. Under high velocity, these molten materials are propelled onto a substrate, causing a high integrity coating with excellent bonding.
Advantages of Plasma Spray
- Resistance to wear, corrosion, abrasion, heat, oxidization and electricity
- No distortion as substrate is not heated above 250°F
- Substrate can be from any variety of materials such as any type of metal, ceramic, some plastics, and we have even sprayed onto wood with good results
- Bonds can be either mechanical, semi-fused or fused metallurgically
- Free-standing parts can be made from plasma sprayed coatings by spraying onto a removable substrate. A&A Coatings has made parts from materials such as tungsten, tungsten carbide, ceramic and many other combinations
- Coatings are unlimited. Metals, ceramics, cermets and refractory materials can be sprayed. Also, with our laboratory facilities, many combinations of materials can be blended for special effect coatings
Some Plasma Spray Applications
- Salvage worn parts
- Gas turbines
- Jet engine protection
- Printing rolls for laser engraving
- Piston rings
- Research and development
- Manufacturing free standing parts
- Wear Resistance
- Thermal Barrier
- Corrosion Resistance
Due to our vast experience in the field of metal and ceramic coatings as well as the capabilities of our laboratory facilities, engineering department, and machining facilities, A&A Coatings is highly capable of assisting you in any phase of thermal spray coatings.