Plasma Alumina-Titania
Quick Spec Summary
| Spec | Value |
| Composition | Titanium dioxide 13%, aluminum oxide balance |
| Macrohardness | Rc63 |
| Cross-sectional hardness | 850–1000 DPH300 |
| Dielectric strength | 300 volts/mil |
| Bond strength | Not quoted as a fixed figure — substrate/prep dependent, tested on request |
| Service temperature | ≤540°C (1000°F) |
| Surface finish achievable | 2–4 µin aa lapped; 10–20 µin aa ground |
| Substrates | Carbon/alloy steels, stainless, nickel alloys, cast iron, aluminum alloys (bond coat required) |
| Industries | Automotive, polymers & plastics, power/gas/oil, metal & steel, pumps, textiles |
| QA / Spec | AS9100 & ISO 9001 certified, NADCAP-compliant, full lab cert on request |
A Ceramic That Handles Heat, Wear, and Current
Alumina-titania is a mix of two ceramics. Aluminum oxide does the heavy lifting. Titanium dioxide rides along and changes how the coating behaves. The pair give you a surface that is tough, hard, and steady against heat and chemicals. It also blocks electrical current, which not every ceramic can do.
We spray it with plasma at A&A Coatings. Across the industry, alumina-titania is also applied by detonation spraying, HVOF, CVD, and PVD — plasma spray (APS) is simply the process we’ve standardized on here. Few materials in our lineup pull triple duty like this one. Thermal barrier. Electrical insulator. Wear surface. All from the same coating.
Need a quote? Call 888-725-0150 or send us a request. Our team replies the same business day.
What Makes This Material Different
Most ceramics are specialists. Good at one thing, weak at the rest. This one spreads its bets.
Start with heat. Alumina-titania hardly conducts it, so the coating acts like a shield. Heat stays on one side. Parts on the other side stay cooler. That is the thermal barrier effect, and it matters in exhaust systems, furnace components, and anywhere a metal part sits close to a flame.
Then there is expansion. Heat a metal part and it grows. Heat a ceramic and it usually grows too, just at a different rate. That mismatch causes stress at the bond line. Alumina-titania barely moves when it heats up, which keeps that stress low and the bond intact.
Thermal shock is the next test. Some ceramics crack when the temperature swings hard. This one holds. You can move a coated part from a hot zone to a cold one without watching it fail. It is also cryogenically compatible, which means it works in cold service where other ceramics get brittle.
The coating also fights off high temperature corrosion and abrasive wear. It resists most alkalis and acids, including corrosion from dilute alkali solutions. And it does something the other ceramics do not. It repels water based liquids. Most ceramics soak them up. Alumina-titania makes them bead and roll off. That trait keeps the surface dry and clean, which matters in chemical and food grade settings.
One more number worth knowing. Dielectric strength comes in at 300 volts per mil. That is a measure of how well the coating stops current. If your part needs electrical insulation on a metal surface, this is a candidate.
Powder Data
| Composition | Titanium dioxide 13%, aluminum oxide balance |
| Size range | -270 mesh +15 microns, or -53 +15 microns |
| Melting point | 1840°C (3340°F) approximate |
Two size cuts are stocked. The right one depends on your spray setup and the thickness you are building. Send the part details and we will point you to the right cut.
Coating Properties
| Texture, as sprayed | 250 to 350 microinches aa |
| Finish, ground | 10 to 20 microinches aa |
| Finish, lapped | 2 to 4 microinches aa |
| Macrohardness | Rc63 |
| Cross-sectional hardness | 850 to 1000 DPH300 |
| Dielectric strength | 300 volts per mil |
| Density | 3.5 g/cc |
| Coating weight | 0.018 lb/ft² per 0.001 inch |
The lapped finish is the standout. Two to four microinches aa is smooth enough for seal faces, precision surfaces, and any part where friction has to stay low. Ground finishes run 10 to 20. As-sprayed texture is rougher but still smoother than most ceramics right out of the gun.
Rc63 puts this material in the mid range for hardness. Softer than chromium oxide, harder than some others. The dielectric strength is what sets it apart.
Porosity
Porosity in alumina-titania coatings is negligible. That is rare for a plasma sprayed ceramic. Most ceramics have some open pores that need sealing before they go into chemical service.
We still recommend a sealer for corrosive chemical environments. That is standard practice. But the raw coating is dense enough to hold up in many wet applications without it.
How dense? Unsealed coatings were exposed to a 2% salt solution for five weeks. No penetration to the base material was found. That test tells you what you need to know about the coating’s ability to keep liquids away from the part underneath.
Heat Limit
There is a ceiling on this material. Above 540°C (1000°F), the coating changes structure at the atomic level. It loses its flexibility. Cracks follow, and once they start, the coating is done.
That limit applies to the coating itself. If your part runs hot, tell us before you spec this material. We will tell you straight if it fits or if you need a different ceramic.
How Thick It Can Go
This material is designed for thin coatings. Keep it between 0.020 and 0.025 inches (0.5mm to 0.63mm).
Spray it thicker and the odds of failure climb fast. That is true of all fine powder ceramics, not just this one. The particles are small, the coating builds stress as it thickens, and thin layers are the way to keep that stress under control.
If your print calls for more than 0.025 inches, talk to us before you send the part. There may be another material or a different approach that fits.
Surface Preparation
Prep matters with any ceramic, and it matters here. The surface has to be clean and free of oxides. We use a light grit blast to strip the surface and give the coating something to grip.
In most cases, a bond coat is also needed. The bond coat goes down first, then the alumina-titania goes on top. It acts as a bridge between the base metal and the ceramic, which improves adhesion and helps the coating survive thermal cycling.
Substrate specific requirements vary. Tell us what your part is made of and we will tell you what prep it needs.
Substrates
Alumina-titania works on a range of metals when the surface is prepped properly. Common substrates include:
- Carbon and alloy steels
- Stainless steels
- Nickel based alloys
- Cast iron
- Aluminum alloys
The bond coat step is what makes this material work on so many base metals. Without it, adhesion drops and the coating can fail in service.
Finishing
We can take alumina-titania to whatever finish your print calls for.
| As-sprayed | 250 to 350 microinches aa |
| Ground | 10 to 20 microinches aa |
| Lapped | 2 to 4 microinches aa |
Ground finishes hit the required size. Lapped finishes go smoother. If your application needs a specific surface, tell us at quote time and we will match it.
Industries and Applications
Alumina-titania shows up in a wide range of industries. The common thread is a part that needs wear resistance, heat resistance, or electrical insulation.
Automotive. Exhaust components, sensor housings, and engine parts that see heat and wear. The thermal barrier property helps here.
Polymers and plastics. Extrusion screws, dies, and molds that face abrasive fillers and high temperatures. The coating resists wear from glass filled and mineral filled plastics.
Power, gas, and oil. Turbine components, valve parts, and downhole tools. The coating resists high temperature corrosion and abrasive wear in harsh service.
Metal and steel. Rolls, guides, and furnace components. Low thermal conductivity helps keep heat where it belongs, and the coating resists scaling and wear.
Pumps. Wear rings, seal faces, and impellers. The lapped finish is a natural fit for seal faces, and the hardness fights abrasive slurries.
Textiles. Guides, rollers, and contact points that touch thread. The smooth finish keeps fiber running clean and the coating resists wear from constant contact.
A Closer Look at Two Jobs
Take an extrusion screw running glass filled polymer. The glass fibers are abrasive, the barrel runs hot, and the screw wears down over time. An alumina-titania coating gives the screw a hard surface that stands up to the fibers and a thermal barrier that keeps heat in the barrel where it belongs. The screw lasts longer and the process stays stable.
Now picture a valve seat in a high temperature gas line. The seat has to hold a tight seal, resist heat, and fight erosion from fast moving gas. Alumina-titania gives the seat a hard, smooth surface that holds its shape and keeps the seal tight. The valve stays in service and the line keeps running.
How It Compares
Alumina-titania sits in a different spot than the other ceramics we spray. Titanium dioxide is softer and gives the smoothest possible finish. Chromium oxide is harder and takes more abrasive punishment.
What sets alumina-titania apart is the combination. It has the thermal barrier properties the others do not. It resists thermal shock, which the others do not mention. It is cryogenically compatible. And it has high dielectric strength, which makes it the pick when electrical insulation matters.
So the choice depends on the job. If wear is the main threat, chromium oxide. If finish is the main goal, titanium dioxide. If heat, electrical insulation, or thermal cycling drive the decision, alumina-titania is the one to look at.
Sealers
Porosity is negligible, but we still recommend a sealer for corrosive chemical service. The sealer closes the surface and keeps media away from the base metal. Tell us the service conditions and we will name a sealer that fits.
How We Prove It
AS9100 and ISO 9001 certified. NADCAP requirements met. Our lab checks coating thickness, bond strength, hardness, and microstructure before parts ship. Customer specs welcome, with certification paperwork supplied on request.
Bond strength for alumina-titania is high. We do not quote a number here because it depends on your substrate and prep. If you need a figure for your spec, ask us and we will run the test on your part.
Talk to Us
Call 888-725-0150 or send your part details through our quote form. Same business day reply.
Keep Reading
Alumina-titania is one of the materials we run on a plasma spray line. The thermal spray coating processes page covers HVOF, metalizing, plasma spray, and spray and fuse hardfacing, with guidance on how to pick between them.
