Ceramic Thermal Spray Coatings: Processes, Properties, and How to Choose the Right Material
Ceramic thermal spray coatings solve a specific kind of problem: a part needs to survive heat, abrasion, or electrical load that bare metal can’t handle, without changing the part’s dimensions or properties underneath. A&A Coatings applies these through plasma spray — the process our full ceramic materials lineup is built on — and this guide covers how that compares to the other processes in our shop, which material to reach for depending on what’s attacking your part, and where each one has actually been put to work.
How Ceramic Coatings Get Applied
Not every thermal spray process is suited to ceramics. Here’s how the three processes in our shop compare for this kind of work.
| Plasma Spray | HVOF | Flame / Combustion Spray | |
|---|---|---|---|
| Heat source | Ionized gas (plasma arc) — nitrogen/hydrogen, argon/hydrogen, or helium | Combustion of oxygen + fuel, supersonic exhaust | Oxy-fuel flame, powder or wire feedstock |
| Substrate heat | Not heated above 250°F — no distortion | Low heat input, dense coating | Varies by feedstock; generally low distortion risk |
| What it’s best at | Spraying almost any ceramic, cermet, or metal with strong bonding and minimal distortion | Very hard, very dense, low-porosity coatings — mostly carbides and metals | Cost-effective metal coatings; combustion powder spray can also carry ceramic/cermet powders below 5500°F |
| A&A’s ceramic materials | All of them — every ceramic on this site is plasma sprayed | None of A&A’s current HVOF materials are oxide ceramics (our HVOF lineup is carbide-based: chromium carbide, tungsten carbide, aluminum bronze) | Used mainly for abradable coatings and spray/fuse hard surfacing, not the oxide ceramics covered here |
| Typical applications | Turbine blades, piston crowns, pump seals, printing rolls | Pelton turbines, landing gear, hard chrome replacement, valves | Bridges, pipelines, boiler repair, offshore structures |
The short version: if the job calls for an oxide ceramic, it’s going on with plasma spray. HVOF and flame spray are real, useful processes in their own right, just not the ones that produce this family of coatings. For more on how each process works mechanically, see our plasma spray coating, HVOF coating, and metalizing pages, or the full process overview.
Choosing a Ceramic by Property
Different ceramics win on different axes — hardness, finish, heat ceiling, electrical resistance. No single material leads on all of them, which is why A&A runs several. Here’s how they stack up on the properties that usually decide the spec.
| Material | Macrohardness | Max service temp | Finest finish achievable | Bond strength | Leads on |
|---|---|---|---|---|---|
| Plasma Chromium Oxide | Rc65–72 (hardest) | 540°C (1000°F) dry; 177–205°C sealed/corrosive | 15–35 µin aa | 4000 psi | Abrasive wear resistance |
| Plasma Titanium Dioxide | Rc53 (softest) | 540°C (1000°F) | 6–8 µin aa ground | Smoothest finish without lapping | |
| Plasma Alumina-Titania | Rc63 | 540°C (1000°F) | 2–4 µin aa lapped | High, not quoted as a fixed figure | Combined thermal barrier + electrical insulation (300 V/mil) + chemical resistance |
| Plasma Zirconia, Titania, Yttria Composite | Rc55 | 980°C (1800°F) surface | 10–15 µin aa | 5000 psi | Extreme heat / true thermal barrier (TBC) work |
| Plasma White Alumina (standard) | Rc60 | 540°C (1000°F) | 45–50 µin aa ground | Good | General-purpose wear, lower cost |
| Plasma White Alumina (premium grade) | Rc65 | 540°C (1000°F) | 15–20 µin aa ground | 5000 psi | Highest dielectric strength (450–500 V/mil); ~2x the wear resistance of standard grade |
Two things worth knowing before you pick by hardness alone: alumina-titania’s lapped finish (2–4 µin aa) is actually the smoothest number on this table, finer than titanium dioxide’s best ground finish — titania just gets there without needing to lap. And premium white alumina, not alumina-titania, has the highest dielectric strength of anything we spray — alumina-titania’s value is that it pairs decent insulation with thermal barrier and chemical resistance in one coating, not that it’s the single best insulator.
Where These Coatings Actually Go to Work
Slurry pump impeller, chromium oxide. Grit and sand move through the impeller all day, and the leading edges wear back fast under that abrasion. A chromium oxide coating gives those edges a hard face that stands up to the grit, so the impeller keeps its shape and the pump stays on line.
Mixer shaft in a corrosive bath, sealed chromium oxide. The shaft turns in a chemical bath that would eat plain steel over time. The sealed coating keeps chemicals off the base metal while the hard surface resists wear from the mixer blades.
Extrusion screw running glass-filled polymer, alumina-titania. The glass fibers are abrasive and the barrel runs hot. The coating gives the screw a hard surface against the fibers and a thermal barrier that keeps heat in the barrel where it belongs — the screw lasts longer and the process stays stable.
Diesel piston crown, zirconia-titania-yttria composite. Combustion happens right on top of the crown. The coating keeps the crown cooler on the inside, bouncing heat back into the combustion chamber where it does useful work instead of soaking into the metal — better fuel economy, longer part life.
Pump seal faces and textile thread guides, premium white alumina. The lapped, low-friction finish is a natural fit for seal faces, and the same finish keeps thread running clean over guides and rollers without snagging.
Light-conducting medical equipment, titanium dioxide. Surfaces prone to biofilm formation get a titania coating; combined with UV exposure, it produces a germicidal effect that helps keep the surface clean between uses.
Talk to Us About Your Application
Every one of the materials above solves a different problem, and the right pick usually comes down to which property is actually under threat in your application — wear, heat, finish, or electrical load. If you’re not sure which one fits, call 888-725-0150 or send your part details through our quote form, and we’ll match the material to the job rather than the other way around.
