When it comes to Flame Spray and Plasma Spray, there are some noticeable differences between the two. In this blog, we will be taking a look into what the flame spraying and plasma spraying processes are, and introducing the main features and benefits of each so you can decide which one works best for your application.
What is Flame Spray?
Before we can look at the benefits of flame spray, it is important to familiarise ourselves with the process itself.
Flame spray is a process that uses an oxy-fuel flame to melt wires and in some cases powders and/or ceramic rods. For wires and ceramic rods, the molten material is then atomised with compressed air to create a spray stream that applies the coating onto the surface being sprayed. With powder flame systems, the compressed air just accelerates the heated particles as no atomisation is required. Flame spray systems are commonly manually operated but it is possible to semi-automate or fully-automate the process if required.
For the purposes of comparison of plasma spray, we will focus on the flame spraying of powders and ceramic rods.
Benefits of Flame Spray
Easy to Use
There are many different advantages to using flame spray, one of these being how easy it is to use. Thanks to the simplicity of the process it is easy to learn, meaning you can train your staff on how to use the flame spray equipment effectively and safely. We do also offer flame spray courses both remotely, online and face to face. For more details, click here.
As well as this, flame spraying does not always require the use of an acoustic spray booth as long as you have appropriately risk assessed the need for extraction, ventilation and noise. This is due to the process producing low noise levels that can easily be addressed with ear protection. With the plasma process/ much higher noise levels are experienced, commonly requiring a higher quality booth. You must also take extra precautions due to the generation of ultraviolet light and ozone by the plasma spraying process.
Cost-effective: Flame Spray
Another benefit of flame spray is the capital equipment costs is much lower compared to the capital equipment cost of plasma spray.
The flame spraying of ceramic powders and ceramic rods is great for applications that do not require a particularly high bond strength, particle cohesion and dense coating.
What Is Plasma Spray?
Plasma spray is the term used to describe gas which has been raised to such a high temperature that it ionises and becomes electrically conductive. In the case of plasma spraying, the plasma is created by striking an electric arc between the nozzle and the electrode inside the plasma gun. The plasma jet then emerges from the nozzle.
Powder particles are injected into this jet where they soften and then strike the surface at high velocity to produce a strongly adherent coating.
Benefits of Plasma Spray
Just like flame spray, there are many benefits to using plasma spray. Where bond strength is more critical and where the coating needs to be denser the plasma spray is an excellent solution.
Also, another great advantage of the plasma spray process is that it can spray a larger variety of refractory ceramic powders, nano powders in a liquid suspension and many other materials that can be manufactured in powder form. This spraying process offers components a wide range of benefits such as corrosion protection, wear resistance, and heat and oxidation resistance to name just a few.
One example is applying a thermal barrier coating (TBC) which are ceramic coatings, widely used on modern aero engines and land-based turbines. They can also be applied to vehicle exhausts, turbocharger casings, heat shields and other vehicle components to reduce heat transfer and improve vehicle performance. Heat soak from hot exhaust systems transfers into other vehicle components causing reduced performance or damage.
Thermal Barrier Coating (TBCs) are used in motorsport and on high-performance vehicles to reduce this heat soak effect. The TBC's give two benefits: Keeping the heat in the exhaust system reduces under bonnet temperatures and keeps the heat energy in the exhaust gas which increases gas velocity, thereby improving the thermodynamic performance of the turbocharger. Both effects enable more power to be produced and to improve reliability.
The Thermal Barrier Coating system can be applied with the Powder Flame system- MK74 Powder Pistol. The Mk74 Powder pistol is handheld with the delivery of the powder through a small gravity fed hopper mounted on the pistol or a separate powder feeder (2007MF-PF). Fully automated versions of the MK74 are also available.
The Thermal Barrier Coating is typically a two-part process with a bond coat of Ni/Al or Ni/Cr type layer and a top coat of a suitable ceramic.
Powder flame applied Thermal Barrier Coatings are an excellent solution for most exhaust related applications. However, for extreme performance applications, the thermal barrier coatings can also be applied by the plasma spraying process, producing coatings that are denser and with higher bond strengths than with powder flame spray.
The Final Finish
There are a large range of benefits to using flame spray and plasma spray. But which process is best for you? Speak to a member of our team today and we will work with you to find the ideal solution that fits your budget and your work environment. Metallisation has been working in the metal coating industry since 1922, in that time becoming the leading UK developer, manufacturer and worldwide supplier of a full range of metal spraying equipment and consumables.
If you have any questions, need advice or would just like to find out more about flame or plasma spraying; get in touch with a member of the Metallisation team today on 01384 252 464 or send us an email on sales@metallisation.com. We look forward to hearing from you.
