Titanium oxide is our toughness play in the oxide-ceramic family — softer than alumina, far softer than chromia, but with a thermal-shock and bond-density advantage that makes it the right answer when parts see heat cycling and moderate wear. We spray it as 99% TiO2, fused-and-crushed Metco 102 or AMPERIT 782 grade, by atmospheric plasma over a bond-coated substrate.

Published data puts hardness in the 650 to 870 HV range (Rc50-53), bond strength around 3,000 to 5,800 psi, and porosity between 2 and 4 percent on well-tuned APS runs. Service ceiling is 540°C / 1000°F — push past that and the anatase-to-rutile phase change embrittles the coating. Finish comes off silicon-carbide wet grinding at 6 to 8 Ra microinches, no diamond tooling — a real cost advantage over chrome oxide.

This is the coating for printing and paper-mill rolls that see thermal cycling, plunger-pump surfaces, mechanical seal faces, cylinder-bore liners, and sputter-target mandrels where controlled conductivity matters. The photocatalytic anatase variant opens a specialty lane — UV-activated self-cleaning facades, antimicrobial pharma and food surfaces — though preserving anatase usually takes suspension plasma spray or post-anneal.

Honest caveats: TiO2 dissolves in strong alkalis and concentrated sulfuric acid, it's not a dielectric, and it won't hold chromia's abrasion duty. Tell us the service and we'll tell you if titania is the match.

Technical data

Hardness: 650-868 HV typical APS (DPH300 ~650 on Metco 102 fused-and-crushed; 730-868 HV0.2 measured on SG-100 APS across parameter window)
Hardness (HRC): Rc50-Rc53 macrohardness (A&A plasma titanium dioxide spec; HTS blog cites 50-53 HRC)
Bond strength: 3,000-5,800 psi (20-40 MPa) typical APS; optimized Ti0.5 composite reached 26.2 MPa in sealed test; softer grade than Al2O3 trades hardness for toughness and better bond density
Max service temp: 1000°F upper service ceiling (Oerlikon Metco DSMTS-0065.6 and A&A spec); phase transformation above this threshold embrittles the coating
Max service temp: 540°C hard limit; melting point 1843°C (3350°F) per Metco, 1920°C (3490°F) per A&A, but service is governed by phase change not melt point
As-sprayed porosity: 2.1-3.9% measured on APS with Metco 102 across nine parameter sets; 2-8% broader range depending on gun, H2 flow, and standoff; higher-porosity variants intentional for thick photocatalytic or filter builds
Typical thickness: 5-25 mils (0.005-0.025 in, ~125-640 µm) per A&A and HTS specs; research APS coatings routinely 100-140 µm; the lower melting point vs Al2O3 lets you build thicker without spallation
Surface finish (Ra): 300-400 µin RMS as-sprayed; 6-8 µin aa ground with silicon-carbide wet grinding; HTS blog cites 8 Ra-in achievable with polish
Density: 4.1 g/cc (A&A spec); melting point 1843-1920°C; crystal phases anatase and rutile depending on spray parameters

Where it earns its keep

Tougher than Al2O3 — lower melting point (1843-1920°C vs 2054°C alumina) means splats flatten better on impact, yielding denser lamellae, better bond density, and less spallation under thermal cycling
Superior thermal-shock resistance vs alumina for moderate-temperature sliding service — you can cycle a TiO2-coated roll harder without crazing the ceramic
Grinds and polishes to 6-8 µin aa with silicon-carbide wheels (cheaper than the diamond tooling Cr2O3 demands) — economical finishing for precision surfaces
Slightly conductive oxide: stoichiometry-controlled Metco 623XX grades produce coatings with defined electrical resistance, useful for oxygen sensors, sputter-target mandrels, and static-dissipating printing rolls
Photocatalytic variant in anatase phase provides a genuine specialty lane — UV-activated self-cleaning facades, antimicrobial surfaces (>99.7% E. coli kill reported on suspension-sprayed TiO2-SrCO3 heterostructure), and water/air purification coatings
Biomedically qualified and non-toxic; pure TiO2 is FDA-compatible for food-contact and medical use; widely studied for bone-implant osseointegration
Lower feedstock cost than chromia; economical ceramic option for moderate-wear service where Cr2O3 or Al2O3 is overkill

Where it doesn't

Lower hardness than Al2O3 (~650-870 HV vs alumina's 820-1150 HV) and much softer than Cr2O3 (900-1200 HV) — not the right pick for severe abrasion, hard-grain cutting service, or aggressive slurry erosion
540°C / 1000°F absolute service ceiling — phase transformation (anatase/rutile expansion and cracking) above that; step to Al2O3 for hot wear
Soluble in strong alkalis and concentrated sulfuric acid — TiO2 is not chemically inert across the board; verify the service chemistry before spec'ing it
Photocatalytic performance is phase-dependent: anatase is active, rutile mostly is not, and plasma spray naturally favors rutile because of rapid cooling. Suspension plasma spray or post-anneal is typically needed to preserve anatase content for biocidal/self-cleaning duty
Not an electrical insulator — the slight conductivity that makes it useful for static dissipation disqualifies it where Al2O3's dielectric strength is required

Sources

Data points on this page draw on the following published references. Nothing here replaces a material-specific review by our process engineers — but it's the working starting point.

Oerlikon Metco DSMTS-0065.6 — Pure Titanium Oxide Thermal Spray Powders (Metco 102, Metco 6231A/6232B/6233C/6233D, Amdry 6505/6510)
“Classification: Oxide ceramic, titania based; Chemistry TiO2 99.0+; Melting Point 1843°C (3350°F); Service Temperature ≤540°C (1000°F); Process: Atmospheric plasma spray, combustion powder Thermospray, or press and sinter. Do not use these coatings at higher temperatures to avoid potential cracking as a result of phase transformation. Typical uses: electrically conductive sputter targets, sliding wear on automotive cylinder bore liners, oxygen sensors, decorative dark grey coatings, dry cell battery mandrels, biomedical implants, filter elements and membranes.”
A&A Company — Plasma Titanium Dioxide Technical Data
“Titanium Dioxide 99% minimum; macrohardness Rc53; cross-sectional hardness DPH300 650; density 4.1 g/cc; melting point approx 1920°C (3490°F); coating weight .021 lb/ft²/.001 in; as-sprayed texture 300-400 µin RMS; ground finish 6-8 µin aa; recommended thickness 0.020-0.025 in; maximum operating 540°C (1000°F); phase transformation above causes embrittlement and cracking; finish with wet silicon-carbide grinding.”
HTS Coatings — Three Common Types of Ceramic Thermal Spray Coatings (Titanium Dioxide section)
“Titanium dioxide hardness 50-53 Rockwell C; surface finish 8 Ra-in achievable; thickness range 0.005 to 0.025 in; operational limit up to 1000°F; performs well in sliding wear and wear from abrasive grains; good corrosion resistance except in the presence of alkalis and sulfuric acid; budget-friendly option compared to chrome oxide and aluminum oxide.”
Płatek et al., Advances in Science and Technology Research Journal (2024) — Effects of APS parameters on structure and mechanical properties of TiO2 coatings (Metco 102 on 1.4301 stainless, SG-100 plasma torch)
“Hardness of the samples ranged from 730 ± 102 to 868 ± 91 HV0.2; Young's modulus 206 to 216 GPa; porosity 2.13% to 3.89% (typical or even low for APS); thickness 100 ± 7 µm to 139 ± 9 µm; powder feed rate drives thickness, spray distance drives Young's modulus, hardness, and porosity; hydrogenated black-titanium-oxide (BTO) photocatalytic coatings deposited in one-step APS process with Ar/H2 plasma mixture.”
Höganäs AMPERIT Thermal Spray Powders Guide — AMPERIT 782 TiO2 (fused and crushed, black)
“AMPERIT 782 TiO2 fused and crushed (black): 782.001 (45/22 µm), 782.002 (90/45 µm), 782.003 (45/5 µm), 782.054 (45/10 µm). APS process. Moderate wear resistance compared with Al2O3 or Al2O3-TiOx. Soluble in alkalis and sulfuric acids. Decorative black coatings. Slightly conductive. Used for the production of sputter targets.”
Toma, Berger et al., Journal of Thermal Spray Technology (2014) — Milestones in Functional Titanium Dioxide Thermal Spray Coatings: A Review
“TiO2 feedstock commonly found as irregular fused-and-crushed powder with particle sizes 10-70 µm; anatase exhibits hydrophilic, antimicrobial, and photocatalytic properties and is the active photocatalyst; rutile is less active; plasma spray naturally favors rutile due to rapid cooling; suspension plasma spray preserves anatase fraction for photocatalytic and biocidal applications.”
Journal of Thermal Spray Technology (2020) — Thermal-Sprayed Photocatalytic Coatings for Biocidal Applications: A Review
“Suspension plasma sprayed TiO2 coatings for water and air purification; TiO2-SrCO3 heterostructure nanomaterial coatings for visible-light-induced disinfection exhibited superior bactericidal activities against E. coli (killing rate over 99.7% within about 4 h); photocatalytic reaction works even when cells cover the surface and bacteria are actively propagating.”
Journal of Asian Ceramic Societies (2023) — Effect of TiO2 on mechanical and thermal properties of Al2O3-based coating via atmospheric plasma spraying
“Pure Al2O3 hardness 1050 HV0.3; Al2O3+40 wt% TiO2 hardness 750 HV0.3 — increasing titania content deteriorates hardness but improves toughness. Al2O3-40%TiO2 coating exhibited relatively inferior mechanical properties but superior thermal insulation and thermal shock resistance at 600°C; AT13 thermal shock resistance reached 40 cycles at optimized parameters.”

Material data on this page is provided as a general reference and can vary by lot, substrate, and application. Contact HTS to confirm the right material and specification for your specific part.

Titanium Oxide

Technical data

Where it earns its keep

Where it doesn't

Typical applications

Wear modes addressed

Industries

Substrates

Sources

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