Thermal Spray Coatings in Industries: Applications & Technology

Most manufacturers don't tear apart worn-out parts - they tear them out because no one bothered to actually protect the parts in the first place.

Thermal spray coatings are like a breath of fresh air in this department. Rather than on the constant upgrade treadmill with your components - swapping them every few months - you can just slap on some coatings that withstand wear, corrosion, and extreme heat for years.

We're talking about a tech that's had a huge impact on industries like aerospace, energy, and heavy manufacturing - keeping them up and running with minimal downtime.

But here's the catch: not all spray coatings are made equal, and using the wrong one can end up costing you more than the part ever did.

This article is designed to give you the whole picture on thermal spray coatings, covering:

• Exactly where they get used across the big industry, and what real problems they actually solve on the ground
• How they really work, from flame spraying right through to plasma-based systems - and what sets each one apart

If you've been weighing up your options on surface protection or trying to figure out which coating is the best fit for your operation, you're in the right place. We'll break it all down so you can match the right coating to the right application with confidence.

Which Industries Make the Most of Thermal Spray Coatings

Every single industrial sector has one thing in common: parts wear out before anyone has budgeted for it. Thermal spray coatings are the answer for engineers looking to stretch out the lifespan of their components well past what the raw materials alone could handle. Below is a run-down of where thermal spray coatings make the biggest difference and why they make a difference in each instance.

Aerospace and Aviation Components

Aircraft engines are put through the wringer - turbine blades, combustion chambers, and landing gear all get to experience some serious heat (and we're not talking about a gentle simmer). Thermal spray coatings shield these components from oxidation, thermal fatigue, and erosion at temperatures that would likely knock most uncoated metals out in weeks.

Thermal spray coatings most commonly used in aerospace include:

• Thermal barrier coatings (TBCs) - the ones that keep turbine blade surface temperatures in check and extend service intervals by a huge margin
• MCrAlY bond coats - the ones that tie on some serious oxidation resistance to superalloy substrates before the topcoat goes on
• Abradable seal coatings - the ones that get gas path clearances tightened up without risking a hard touch between rotating and stationary parts

Oil, Gas, & Energy Generation

Downhole drilling tools, pump shafts, valve seats, and boiler tubes all get pummelled by abrasive particles, corrosive fluids, and high-pressure environments. When these parts go down, production stops, and costs go through the roof.

Operators are relying on coatings like tungsten carbide and chromium carbide to give wear resistance a serious boost on critical surfaces. In power generation, coatings shield boiler tubes from hot corrosion and fly ash erosion - both of which are among the most common causes of unplanned outages in coal and biomass plants.

Automotive & Heavy Transport

Engine cylinder bores, piston rings, and brake components all get a lot of mileage out of thermally sprayed surfaces. Coatings cut friction losses right down, improve heat dissipation, and cut the need for frequent part replacement in high-mileage commercial vehicles.

Some of the more targeted uses include:

• Cylinder bore coatings - the ones that strip weight out of engine blocks by eliminating the need for all that heavy cast iron liners
• Wear-resistant layers on synchronizer rings & transmission parts - the ones that keep performance steady under repeated load cycling

Textile & Wire Drawing Machinery

This is where precision and surface finish really matter. Pulleys, capstans, cone pulleys, and guide rollers in wire drawing and textile equipment need coatings that resist abrasion without messing up the product.

Chromium oxide and alumina-titania coatings are popular picks here because they deliver hard, smooth surfaces that protect the machinery and the wire or yarn as it passes over.

Printing & Paper Processing

Anilox rollers, doctor blades, and drying cylinders in printing and paper mills all get constant surface contact. Thermal spray coatings keep surface profiles consistent over long production runs, which directly affects print quality and paper thickness uniformity.

Word to the wise: the coating material is less important than the coating process you choose in applications where surface finish tolerances are tight. A well-applied chromium oxide layer will outperform a poorly sprayed tungsten carbide coat every time - regardless of the hardness ratings.

The Lowdown on Thermal Spray Coating Tech

At its core, every single thermal spraying method is built on the same fundamental principle. You heat up the feedstock material (powder, wire, or rod) until it's just about molten, then give it a boost towards a surface that's been prepped just right, and it bonds on impact. The upshot is a coating built up one particle at a time, layer by layer.

But the way each method heats and gets that material moving is what really sets the final coating's density, adhesion, and performance apart from each other. Pick the wrong process for what you need, and you're trying to put a square peg in a round hole.

Plasma Spray (APS)

Atmospheric Plasma Spray - the process of choice when you need to handle high-temperature coating applications. You get a plasma arc lit up between an electrode and nozzle, that gets an inert gas buzzing like crazy, creating a high-speed jet that can reach temperatures that make your head spin - over 10,000 degrees Celsius. Powder feedstock gets injected right into that jet, melts in an instant, and then slams into the substrate at a high, high velocity.

What makes APS a standout among other methods:

• Does a fantastic job with ceramics - we're talking about zirconia, chromium oxide, and alumina-titania blends that some other processes just can't quite melt properly
• Let's you apply thick coatings in fewer passes - that means you can crank out large components a lot faster
• Works with almost every single type of coating material - from all-ceramic to metallic and even cermet compositions

APS is usually the go-to for thermal barrier coatings on turbine blades and ceramic wear surfaces on huge industrial rollers and pulleys in factories.

High-Velocity Oxy-Fuel (HVOF)

HVOF is a different animal altogether. It prioritizes getting those particles moving at breakneck speed over raw heat. You mix a fuel gas (hydrogen, kerosene, or propylene) with oxygen in a confined space, and the end result is a gas stream that blasts powder particles at the substrate faster than most other spray methods.

The end result is a much denser, way harder, and less porous coating with a way stronger bond. HVOF coatings made with tungsten carbide are usually the standard for parts that take a pounding - either from wear or abrasive use.

Some key applications include:

• Key parts in oil rigs, like pump shafts and valve components - these things need to be bulletproof
• Aerospace landing gear and actuator rods - we can't have these failing in mid-air
• Any surface where just being tough will do the trick, like your wire drawing capstans and pulleys - a bad finish on those can tank an entire production run

Electric Arc Spray

You have two wires being fed towards each other, and when they meet up, an electric arc melts them right at the point of contact. Then compressed air atomizes the molten metal and gives it a push onto the substrate.

This process is super fast and super cheap, and it's just built for big surface areas - like boiler tubes, bridge structures, and storage tanks. The catch is that the coating microstructure is a bit rougher than what you'd get with HVOF or plasma, so it's better suited for applications where corrosion protection is the main game, and surface finish isn't as high a priority

Flame Spray

Flame spray is the granddaddy of thermal spray methods. An oxy-fuel flame melts the feedstock (powder or wire), and a gas stream carries it onto the target surface.

It runs at lower temperatures and velocities than the other methods listed above, which limits it to a few specific uses:

• Dimensional restoration on worn shafts and bearing surfaces - getting the original shape back
• Corrosion-resistant layers using zinc or aluminum on structural steel - a cheap but effective way to keep rust at bay
• Low-cost protective coatings where extreme hardness isn't the primary goal - just slap on a layer to keep things safe

Pro Tip: If your application calls for something with a hardness above HV 900 and porosity below 2%, HVOF should be at the top of your pile. For ceramic coatings that need thermal insulation, plasma spray is the way to go.

Frequently Asked Questions

How long does a thermal spray coating last?

Well, that depends on the coating material, the spray process used, and what kind of environment the part is in. A well-applied tungsten carbide HVOF coating on a pump shaft can last for years under heavy abrasive conditions, while a flame-sprayed zinc layer on structural steel may keep corrosion at bay for a decade or more in mild atmospheric exposure. Really, it comes down to matching the right coating and process to the specific wear mechanism your part faces.

Can thermal spray coatings be applied to any metal?

Most industrial metals and alloys are fair game for thermal spray coatings - we're talking steel, stainless steel, aluminum, titanium, and nickel-based superalloys. Some substrates might need a bit of prep work before the topcoat goes on - like a grit blast or bond coat application. Non-metallic substrates like certain composites and ceramics can also be coated, but you'll need to adjust the process parameters to avoid thermal shock or poor adhesion.

How do you choose between HVOF and plasma spray?

It all comes down to what your application demands most. Here's a quick rule of thumb:

• Go with HVOF if you need a dense, hard coating with minimal porosity for parts that take a pounding - like valves, capstans, or landing gear components
• Go with Plasma Spray (APS) if you're applying ceramic materials for thermal insulation, electrical insulation, or high-temperature oxidation resistance
• Consider your budget and part size because HVOF tends to cost more per square inch, while plasma spray covers large surfaces and builds thickness up faster

If you're still unsure, just give your coating provider a call - they should be able to give you the lowdown on what you need to do to get the right coating on your part.

Get Your Thermal Spray Coatings Right with CY Thermal Spray

You've now got a solid working knowledge of where Thermal Spray Coatings fit in across all sorts of industries, and how each and every spray method stacks up against the others - that puts you in a considerably stronger position to make those all-important coating decisions that will actually cut it in the real world.

Here's a quick catch-up on what we went over :

• Thermal spray coatings can be a real lifesaver for critical parts in all sorts of aerospace, energy, automotive, textile, and printing applications
• Plasma spray (APS) is actually pretty unbeatable when it comes to handling those ceramic coatings and high-temperature protections
• HVOF is the go-to for getting those super dense, super hard coatings out in situations where wear and tear is going to be extreme
• Electric arc spray is actually your better bet for large area corrosion protection - and it won't break the bank
• Flame spray is the way to go when you've got to restore dimensions on something or add a basic protective layer - and it's a pretty practical choice
• At the end of the day, it's the process you choose that's going to make all the difference in how your coatings perform,  just as much as the material you pick is

If you're shopping for thermal spray coatings for your operation, you should definitely give CY Thermal Spray a shout. We've got serious expertise in tungsten carbide, chromium oxide, zirconia, and alumina-titania coating systems - and we even custom-manufacture coated components based on your exact drawings and specifications.

Getting the right coating on the right part is a game-changer. So make sure you choose both of those things correctly.