THERMAL PLASMA AND HVOF SPRAY COATINGS
Used in the aerospace, automotive, power generation and oil and gas industries, Curtiss-Wright’s thermal spray coating service options include HVOF (High Velocity Oxy-Fuel), HVAF, plasma, flame and arc wire spray. These technologies can produce a cost effective and high performing coating that protects components from heat, wear, corrosion, fatigue and oxidation. HVOF coatings in particular are a viable alternative for hard chrome plating.
Our thermal coatings can repair damaged and worn components – such as gas and steam turbines – to original specification
Benefits of Thermal Spray Coatings
There are a number of benefits in using thermal spray technology over more traditional coating methods and these include:
- Versatility in the choice of coatings – options include metals, alloys, ceramics and carbides among others.
- Protection against wear, corrosion, fatigue, oxidation and high temperatures depending on the coating used in the process.
- Controlled temperature of the bulk substrate to 200°C or less avoiding any detrimental effects of heat on the substrate material properties.
- Coating thickness easily controlled, meaning the process can even be used to restore the dimensions of a worn part or incorrectly machined component.
- Complex shapes can be coated as the robotic automation allows for uniform coating of multifaceted parts.
- Excellent bond strength which can withstand extreme mechanical loads and severe wear situations.
Applications for HVOF Thermal Spray Coatings
- Gas turbine engines
- Intake section (cold)
- Compression section (cold)
- Combustion section (hot)
- Exhaust (hot)
- Intake snouts
- Compressor blades and vanes
- Combustion flame tubes
- Honeycomb seals
- Power turbine discs
- Rings and seals
Powder particles (typically 20 to 120 microns) are heated to a molten or semi-molten state and are propelled at the substrate at high temperature and velocity. The molten particle form a “splat” on the surface, which contracts as it cools to form a strong bond with the surface. Subsequent splats build up in layers to generate the required thickness and density.
CWST turbomachinery thermal spray coatings deliver technologies essential to today’s high performance, high quality industrial turbines, including
- Thermal Management
Thermal Barrier Coatings can maximize turbine efficiency by allowing higher firing temperatures while reducing component thermal fatigue, warpage, oxidation and cracking. The combination of ceramic and super alloy constituents in GPX Thermal Barrier Coatings reflects heat back into the combustion gas path and insulates parts, effectively lowering their surface temperatures.
- Wear Control
Wear due to vibration, friction, thermal gradients and pressure shortens the life of turbomachinery components. And if left unchecked, can cause expensive unscheduled outages. Coating that controls wear can prolong the life of critical turbomachinery parts by as much as 10 times. Anywhere metal touches metal is a candidate for Wear Control coatings.
- Corrosion Control – Low Temperature
Corrosion of turbomachinery components costs operators billions of dollars every year through premature part failure and induced aerodynamic drag. Coatings for corrosion control can dramatically reduce corrosion damage while providing a smooth aerodynamic surface on compressor blades and stator assemblies. Tough CWST Coatings also provide resistance to erosion from dust and high velocity gases.
- Corrosion Control – High Temperature
Turbine components exposed to corrosion at high temperatures (+ 1,000 °F) not only degrade faster than at lower temperatures, but also are subjected to cracking due to thermal fatigue and cycling. High Temperature Coatings are diffused into the substrate, creating a nearly impermeable oxide surface which can reduce scaling and cracks due to thermal cycling.
- Oxidation Control
High temperature oxidation is a condition in gas turbines most responsible for premature failure of “hot section” components. As designers continue to raise turbine firing temperatures, super alloy components are nearing their theoretical limits. Oxidation Resistant Coatings are extending these limits by impeding oxygen penetration of the component surface while providing a sacrificial layer capable of protecting the part between overhauls.
- Solid Particle Erosion Control
Solid particle erosion claims tons of steam turbine components every year and is most responsible for premature turbine failure. Often coupled with foreign object damage, solid particle erosion can be controlled effectively when temperature, impingement angle, velocity and size of erosion particles have been considered. Solid Particle Erosion Coatings are specifically designed and tested for this environment and have proven effective in extending the life of critical steam turbine parts.