If you’ve worked in industrial equipment, aerospace components, automotive parts, or even power generation gear, you know thermal spray coatings are a game-changer for extending part life. But here’s the thing: not all thermal spray coatings hold up as well as they should to friction, abrasion, corrosion, and all the other daily wear that hits your parts. As a thermal spray supplier that’s been in this game for over a decade, I’ve heard it all: “My coating chipped off after a month,” “It wore out way faster than the spec said it would,” “I paid for a hard coating and it’s already scratched through.” Thermal Spray
The good news? Improving the wear resistance of your thermal spray coatings isn’t rocket science—It’s about small, intentional choices that add up to big results. I’ve seen clients skip these steps, only to end up replacing parts way more often than they need to. Let me break down what actually works, from powder prep to post-coating checks, no fancy jargon (I’ll keep it casual, promise).
First up, the raw material: your spray powder. A lot of suppliers cut corners here, and that’s where wear resistance dies before you even hit the trigger on the spray gun. I once had a client show me a batch of tungsten carbide powder they bought from a random supplier; it had way too much fine dust and inconsistent grain sizes. When we sprayed it, those tiny particles burned off mid-process, leaving gaps and weak, porous spots in the coating. That coating wore through in two weeks.
Why does powder quality matter? Wear resistance boils down to two main things: hardness and density. If your powder isn’t uniform, you can’t get a dense, hard coating. For high-wear apps—like drilling bits, conveyor rollers, or pump impellers—you need powders that are spherical, have tight grain size distribution, and minimal impurities. Tungsten carbide (WC) is the gold standard here, but even WC gets a bad rap if the powder is trash. Some suppliers use lower-grade binder metals (like cobalt with random iron contamination) to cut costs, which makes the coating soft and prone to chipping.
Pro tip from someone who’s tested 100+ powder batches: ask your supplier for powder morphology reports. If they can’t tell you the average grain size, the percentage of spherical particles, or the carbon content (for WC), walk away. I once had a client who switched to our powder because their old supplier’s WC had 2% extra carbon—sounds small, but that extra carbon turned into voids in the coating, which act like weak points for abrasion to attack.
Next, spray process parameters. This is where most people mess up, even if they have good powder. I’ve seen techs crank up the gas pressure too high, or run the gun too fast, just to get the job done quicker. What happens? The particles don’t melt all the way, so they bounce off the part instead of bonding. Or if they run the heat too high, the carbide particles start to break down into softer tungsten and carbon monoxide—ruining the coating’s hardness.
Let’s get specific: for HVOF (high-velocity oxy-fuel) coatings, which are the best for wear resistance, you want particle temperatures just above their melting point, and velocities around 600-800 m/s. If your particles are too cold, they don’t flatten out into those thin, tightly packed splats that stick together. Too hot, and you degrade the hard phases. For plasma spray, it’s a similar call—adjust your gas flow rates (argon, hydrogen, nitrogen) to get a consistent, narrow heat zone, not a big messy flame that burns through your powder.
I worked with a mining equipment company last year that was having issues with their crusher liners wearing out in 3 weeks. We adjusted their HVOF parameters: slowed the gun speed by 20%, bumped the fuel pressure slightly to get better particle heating, and lowered the standoff distance (the gap between gun and part) by 5mm. The result? The coating lasted 12 weeks. That’s not a small win—cutting replacement time by 75% saved them tens of thousands of dollars a month. The takeaway here: don’t just follow a generic spray recipe. Test parameters for your exact powder and part. A good supplier will help you tweak these, not just hand you a spray gun and say “good luck.”
Then there’s surface preparation. If you skip this, your coating might as well not exist. I can’t tell you how many times I’ve seen a part come in with oil residue, rust, or loose paint, and the coating peels off a week later. Adhesion is everything for wear—if the coating isn’t bonded tight to the base metal, any friction will get under it and lift it off.
The standard for prep is grit blasting, but it’s not just “throw sand at it.” You need the right abrasive: angular grit (like aluminum oxide or silicon carbide) to create a rough, micro-textured surface that the coating can “key” into. If you use rounded grit, you get a smooth surface that doesn’t grip the coating. Also, make sure the part is completely clean—no blasting debris, no oil, no moisture. I once had a client who rushed prep, skipped cleaning the blast media, and ended up with silica trapped in the surface. The coating bonded, but the silica was a weak point, and it wore through 2x faster.
Another thing: for parts that are going to see impact wear (like those crusher liners or agricultural tillage tools), you want a surface prep that’s not too aggressive—if you etch the base metal too much, it can develop micro-cracks that spread into the coating. Balance is key here.
Post-coating treatment. A lot of people think once the coating is sprayed, it’s done. But post-treatment can boost wear resistance a lot. Let’s start with grinding: HVOF coatings are a bit rough when they come off the gun. If you machine them to a tight, smooth finish, you reduce friction—less friction means less wear. I know a pump manufacturer that switched from leaving their coatings as-sprayed to grinding them to a 0.8 Ra surface finish. Their pump seals lasted 3x longer.
Then there’s sealing. Wait—sealing? For hard coatings? Yeah, if your coating has any porosity (which even the best ones do, a tiny bit), that porosity can trap dirt, chemicals, or moisture, leading to corrosion from the inside out, which weakens the coating. A good sealant (like a epoxy or a polymer specifically made for thermal spray) fills those tiny pores, preventing debris from getting in. For parts that handle food or pharmaceuticals, we use food-grade sealants, but for industrial apps, a standard acrylic sealant works great.
I also see a lot of people neglect post-coating inspection. Don’t just take the supplier’s word for it—check the coating’s hardness with a microhardness tester, check porosity with a microscope, and do adhesion tests (like a scratch test or a pull-off test). If the coating is supposed to be 65 HRC (hardness on Rockwell C) and it’s only 55, that’s a problem. Last year, a client came to us with a coating that was 50 HRC when they spec’d 62—their old supplier cut corners on powder, and they had to re-do all their parts.
Wait, let’s talk about coating material selection too—this is a big one. A lot of people grab the hardest coating they can find, but that’s not always right. If you need impact resistance (like for parts that get hit with rocks or debris), a 100% WC coating is too brittle—it will chip. Instead, a WC-CoCr (tungsten carbide with cobalt-chromium binder) is tougher, resists both abrasion and impact. For parts that see corrosion plus wear, add chromium to the coating—Cr is corrosion-resistant, so it stops the coating from breaking down chemically, which means it lasts longer.
I had a client in offshore oil and gas a while back—their valve stems were failing because of both abrasion from sand and corrosion from saltwater. We switched them from a plain WC-Co coating to WC-CoCr with a chromium overlay. Their valve stems went from lasting 6 months to 2 years. That’s a massive difference for an industry where downtime costs $$$.
Common mistakes I see all the time: Using the wrong coating material for the job, cutting powder costs, rushing spray parameters, skipping surface prep, and ignoring post-treatment. All of these add up to a coating that doesn’t do what you need it to.
Look, as a thermal spray supplier, we’re not here to sell you a one-size-fits-all coating. Every part has unique conditions: is it exposed to high heat? Impact? Corrosion? Abrasive dust? You can’t use the same recipe for a jet engine turbine blade as you would for a farm plow. That’s why we work with clients to test small batches first—spray a test coupon, run it through your actual wear tests, adjust as needed, then scale up. It’s not magic, it’s just paying attention to the details.
If you’re tired of replacing worn parts, your thermal spray coating not holding up, or just want to get the most out of your coating budget, let’s talk. We can help you figure out the right powder, process, and treatment for your specific application. No fluff, no fine print—just straight talk about what works, and what doesn’t.
X-ray Tube Anode Material References:
- Pawlowski, L. (2008). The Science and Engineering of Thermal Spray Coatings. John Wiley & Sons.
- McPherson, R. (1989). The relationship between particle characteristics and the properties of thermally sprayed coatings. Surface and Coatings Technology, 39-40, 173-185.
- Bergmann, H. W., & Stöver, D. (2000). Wear-resistant thermal spray coatings. Journal of Thermal Spray Technology, 9(3), 315-326.
- Viswanathan, R. (1989). Damage Mechanisms and Life Assessment of High-Temperature Components. ASM International.
- Kuroda, S., & Kawakita, J. (2010). HVOF sprayed coatings for wear applications. Surface and Coatings Technology, 205, S1-S6.
Foshan Jiafengrui New Materials Technology Co., Ltd.
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