Aluminum Oxide (Al2O3)
Aluminium oxide (alumina, Al2O3) is the workhorse ceramic of the thermal spray industry, prized for a rare combination of extreme hardness, chemical inertness, and electrical insulating power. Infinita Materials supplies spray-grade Al2O3 powder engineered for plasma spraying, HVOF, and flame spraying, delivering coatings that shrug off abrasive wear, resist corrosive chemical attack, and hold up under demanding thermal cycling. With purity exceeding 99.8% and a tightly controlled particle size distribution, this powder gives coating applicators consistent flow, predictable melting behaviour, and repeatable coating microstructure batch after batch. From aerospace actuator sleeves to industrial pump components, it is the default choice whenever engineers need a hard, insulating, wear-resistant ceramic surface at a fraction of the cost of exotic alternatives.
| Particle size d50 (μm) : | 40- 60 µm |
| Purity (%) : | >99.8% |
Introduction to Aluminium Oxide Powder
Alumina (Al₂O₃) used for thermal-spray applications is predominantly the thermodynamically stable α-Al₂O₃ (corundum) phase, with a rhombohedral R-3c structure responsible for its exceptional hardness (~9 Mohs), high melting point (~2050–2072 °C), and excellent chemical and wear resistance. Spray-grade powder is engineered for high α-phase content, as transitional alumina phases such as γ-Al₂O₃ are softer and less stable. Unlike sputtering targets, alumina is supplied as controlled powder feedstock for plasma spraying, HVOF, or flame spraying. Particles are heated to a molten or semi-molten state and accelerated onto substrates, forming adherent lamellar coatings. These coatings provide wear, corrosion, and electrical insulation while extending the service life of metallic components.
FAQs
Question: What is spray-grade Al₂O₃ used for?
Answer: Spray-grade Al₂O₃ is primarily used for protective and functional coatings that provide wear resistance, corrosion resistance, thermal insulation, and electrical insulation.
Introduction to Aluminium Oxide Powder
Alumina (Al₂O₃) used for thermal-spray applications is predominantly the thermodynamically stable α-Al₂O₃ (corundum) phase, with a rhombohedral R-3c structure responsible for its exceptional hardness (~9 Mohs), high melting point (~2050–2072 °C), and excellent chemical and wear resistance. Spray-grade powder is engineered for high α-phase content, as transitional alumina phases such as γ-Al₂O₃ are softer and less stable. Unlike sputtering targets, alumina is supplied as controlled powder feedstock for plasma spraying, HVOF, or flame spraying. Particles are heated to a molten or semi-molten state and accelerated onto substrates, forming adherent lamellar coatings. These coatings provide wear, corrosion, and electrical insulation while extending the service life of metallic components.
Key Properties of Aluminium Oxide Powders
| Property | Value | Significance |
|---|
| CAS Number | 1344-28-1 | Unique regulatory and supply-chain identifier used on certificates of analysis and safety documentation |
| Molar Mass | 101.96 g/mol | Stoichiometric reference value (2 x 26.98 Al + 3 x 16.00 O) used for compositional and blend calculations |
| True (Theoretical) Density | 3.95 – 3.99 g/cm3, alpha-phase | Sets the ceiling for coating density and is used to back-calculate porosity in sprayed layers |
| Crystal Structure | Alpha-Al2O3 (corundum), rhombohedral, space group R-3c | Source of the powder’s hardness, chemical inertness, and thermal/dimensional stability |
| Melting Point | ~2050 – 2072 degrees C | Governs how fully particles melt in the plasma/HVOF/flame jet, which controls coating density and bond strength |
| Mohs Hardness | ~9 | Direct basis for the abrasion and sliding-wear resistance of the finished sprayed coating |
| Coefficient of Thermal Expansion | ~8 x 10^-6 /K | Influences thermal-cycling behaviour and spallation risk when coated onto metal substrates with differing expansion rates |
| Volume Electrical Resistivity | >10^14 ohm-cm (bulk, room temperature) | Underpins the coating’s use as a high-voltage electrical insulation layer |
Types & Grades of Aluminium Oxide Powder
Aluminium oxide powder is offered in standard catalogue grades and particle size distributions, with custom purity, morphology, and packaging available for OEM and R&D use.
| Grade / Form | Typical Purity | Key Features / Uses |
|---|
| Fused & crushed alumina (standard purity) | ~99.0 – 99.5% | Angular/blocky particles from crushed fused alumina ingot; dense, cost-effective, workhorse grade for general wear and erosion coatings (e.g. -180+63µm to -45+15µm cuts) |
| Fused & crushed alumina (fine, high-purity) | ~99.5 – 99.65% | Finer angular cuts (roughly -45+5µm) suited to HVOF and finer-flow APS guns; used for hard, dense coatings and electronics/electrical insulation duty |
| Agglomerated & sintered white alumina | ~99.9 – 99.95% | Near-spherical agglomerated/sintered particles give superior flowability and feed consistency; favoured for high-purity biomedical, electronics, and precision coating applications. |
| Chromia-doped alumina (Al2O3-Cr2O3 blends) | Typically 60-97% Al2O3 with 3-40% Cr2O3 | Chromia addition raises coating density, hardness, and friction/wear performance versus pure alumina; common on print rollers, pump sleeves, and high-wear sliding contacts. |
| Titania-doped alumina (Al2O3-TiO2, separate catalog product) | Typically 87-97% Al2O3 with 3-13% TiO2 (up to 40% in tougher grades) | TiO2 addition improves toughness, bond strength, and deposition efficiency at some cost to hardness and dielectric strength; sold by Infinita as a distinct Al2O3/TiO2 spray-grade product |
Applications of Aluminium Oxide Powder
Aluminium oxide powder supports demanding roles across research and production applications where this material’s specific structural, electronic, magnetic, or electrochemical properties are the key requirement.
| Industry | Application | Function |
|---|
| Aerospace | Wear- and heat-resistant coatings on actuator sleeves, bearing housings, and structural fittings | Extends service life of moving parts exposed to friction, abrasion, and thermal cycling |
| Oil & Gas / Chemical Processing | Coatings on pump sleeves, valve components, and reactor or tank internals | Provides corrosion and chemical-attack resistance in aggressive process fluid environments |
| Printing & Textile Machinery | Anilox rolls, print cylinders, and textile guide surfaces | Delivers a hard, low-wear, dimensionally stable surface for continuous high-speed contact |
| Electronics & Power Systems | Insulating layers on circuit boards, connectors, and high-voltage components | Combines electrical insulation with thermal stability to prevent arcing and short circuits |
| Pulp & Paper | Roll and cylinder coatings exposed to abrasive furnish | Resists abrasive wear from fibre and filler particles, extending roll service intervals |
| General Industrial Manufacturing | Wear plates, seal faces, shafts, and pump impellers | General-purpose abrasion and sliding-wear protection plus dimensional restoration on worn parts |
Why Partner with Infinita Materials?
- Technical Depth: in-house quality control with ICP-MS and XRF purity verification, particle size distribution and density measurement, and full certificates of analysis on every lot.
- Global Logistics: reliable supply from single R&D-scale quantities to production-line volumes, with established international shipping.
- Responsive Support: direct access to materials engineers for grade, particle size, and packaging selection, and process-compatibility questions.
Take the Next Step
Infinita Materials manufactures Aluminium Oxide powder engineered to the purity, particle size, and morphology your process requires. Whether the requirement is a standard catalogue grade or a custom particle size distribution, purity, or packaging format, our team can help match the right specification to your process. Request a quote or speak with our technical team to discuss your material specification.
Frequently Asked Questions
What is spray-grade Al₂O₃ used for?
Spray-grade Al₂O₃ is primarily used for protective and functional coatings that provide wear resistance, corrosion resistance, thermal insulation, and electrical insulation.
Aluminum Oxide (Al2O3)
Used in Various Industries
Biomedical
Energy
Aerospace
Automotive
Healthcare
Electronics
