Resources
Technical guides, selection tools, and answers to common questions about alumina products and applications.
Selection Guide
Match your application to the recommended product and grade. Contact us for custom formulations not covered here.
| Application | Product | Recommended Grade | Key Reason |
|---|---|---|---|
| Refractory castables (general) | AF-C Calcined Alumina | AF-C-1 / AF-C-2 | Controlled particle size, good flow properties, consistent alpha phase |
| Refractory castables (low cement) | AF-R Reactive Alumina | AF-R-1 / AF-R-2 | High green density, low water demand, bimodal packing |
| Refractory castables (extreme duty) | AF-T Tabular Alumina | AF-T-1 | Best thermal shock resistance, dense aggregate, low porosity |
| Steel ladle linings | AF-T Tabular Alumina | AF-T-1 (K2–K4) | Exceptional thermal shock resistance at ΔT > 1000°C |
| Slide gate plates | AF-T Tabular Alumina | AF-T-1 (K3/K4) | High bulk density, low porosity, erosion-resistant |
| Technical ceramics (wear parts) | AF-C Calcined Alumina | AF-C-3 | Fine D50 2–5 μm, high alpha, good sinterability |
| Electronic substrates | AF-R Reactive Alumina | AF-R-3 | Ultra-fine D50 0.8–1.0 μm, high sintered density, low soda |
| Ballistic armor | AF-R Reactive Alumina | AF-R-2 / AF-R-3 | High green density, bimodal packing, sintered density ≥ 3.87 g/cm³ |
| Steel and stainless steel finishing | AF-P Polishing Alumina | AF-P-2 / AF-P-3 | High alpha >97%, controlled D50 4–15 μm, balanced cut/polish |
| Metal surface lapping | AF-P Polishing Alumina | AF-P-3 / AF-P-4 | Medium to high cut, stable PSD, consistent stock removal |
| Ceramic glazes | AF-C Calcined Alumina | AF-C-3 | Fine particle size, consistent chemistry, good dispersion |
| Polishing compounds (solid bar) | AF-P Polishing Alumina | AF-P-1 / AF-P-2 | Consistent batch quality, contamination-free, low Na₂O for sensitive alloys |
Alumina Basics
Crystal Phases
Aluminum oxide (Al₂O₃) exists in several metastable transition phases (gamma, delta, theta) that convert irreversibly to alpha-alumina (corundum) upon heating above ~1100°C. Alpha is the only thermodynamically stable phase and is the form supplied in all commercial alumina products.
Key Properties
- • Melting point: 2040–2072°C
- • Hardness: 9 Mohs (second only to diamond)
- • Density: 3.95–3.99 g/cm³ (theoretical)
- • Thermal conductivity: ~30 W/(m·K) at 25°C
- • Chemically inert, excellent dielectric properties
Production Routes
Bayer Process: Bauxite → Al(OH)₃ (gibbsite). This is
the feedstock for all viseray products.
Calcination: Al(OH)₃ heated to 1100–1400°C → alpha-Al₂O₃
powder. Grinding and classification control particle size.
Sintering: Calcined alumina fired at ~1900°C → dense
tabular alumina aggregates.
Electro-fusion: Calcined alumina melted in electric arc
furnace at >2000°C → solidified, crushed, and graded into abrasive
grits.
Applications
In-depth guides on using alumina in specific industrial applications. Each guide covers material selection, formulation principles, and practical considerations.
Refractory Castables: Alumina Selection Guide
How to choose the right alumina raw materials — calcined, reactive, and tabular — for refractory castable formulations. Covers aggregate selection, matrix design, and water demand optimization.
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Steel Ladle Refractories: Tabular Alumina in Steelmaking
How tabular alumina aggregate — with its high density, low porosity, and exceptional thermal shock resistance — performs in steel ladle linings, slide gate plates, and other demanding steelmaking refractory applications.
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Low-Cement Castables: Reactive Alumina Bonding
How reactive alumina replaces cement as the primary bonding phase in low-cement and ultra-low-cement castable formulations, improving hot strength and slag resistance across the full temperature range.
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Metal Surface Finishing with Alumina
How to select polishing alumina grades for multi-stage metal surface finishing — from aggressive stock removal to high-gloss mirror polish on steel, stainless steel, and non-ferrous alloys.
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Technical Guides
Practical how-to guides for interpreting alumina specifications, test data, and quality documents.
How to Read an Alumina Technical Data Sheet
A practical guide to understanding the key parameters on an alumina TDS or COA — particle size, surface area, alpha phase, chemistry, and what they mean for your process.
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D50 and BET: Understanding Alumina Particle Characterization
How particle size distribution (D50) and specific surface area (BET) relate to alumina powder behavior — water demand, sintering activity, reactivity, and packing density in refractory and ceramic applications.
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Low-Soda Alumina: Why Na₂O Content Matters
What sodium oxide (Na₂O) content means for alumina performance — effects on refractoriness, beta-alumina formation, and why low-soda grades are specified for advanced ceramics and sensitive alloy finishing.
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Calcined vs Reactive vs Tabular Alumina
A side-by-side comparison of the three main specialty alumina types — production routes, key properties, typical applications, and how to choose the right one for your process.
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Blog Articles
Technical deep-dives, product comparisons, and application know-how from the viseray team.
Tabular Alumina for Refractories: Properties and Selection Guide
Tabular alumina is the gold standard aggregate for high-performance refractories. Understand its properties, how it compares to calcined and reactive alumina, and how to select the right grade.
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Understanding Alumina Particle Size: D50, D90, and BET Explained
Particle size distribution and specific surface area are the most important parameters when specifying alumina. Here's what D50, D90, and BET actually mean and how they affect your process.
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Calcined vs Reactive Alumina: How to Choose the Right Grade
Calcined and reactive alumina serve different purposes in refractories and ceramics. Understand the key differences in alpha content, surface area, and sintering behavior to select the right material.
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Understanding Alpha-Alumina Content in Refractory Castables
Why alpha phase percentage matters for high-temperature performance and how to specify it correctly in your procurement documents.
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Packaging Guide
Paper Sacks
25 kg multi-wall paper sacks, stacked on 1000 kg pallets, stretch-wrapped. Standard for most powder products (AF-C, AF-R, AF-T fines, AF-P polishing grades). Moisture barrier liner included for reactive grades.
Big Bags (FIBC)
500 kg or 1000 kg flexible intermediate bulk containers with filling and discharge spouts. Standard for tabular alumina fractions and large-volume orders. UV-stabilized fabric for outdoor storage.
Bulk & Custom
Bulk tanker delivery for high-volume calcined alumina. Container liners for ocean freight of tabular alumina. Plastic drums for fine micro grits. Custom pallet configurations available.
Technical Data Sheets
Download detailed specifications, chemical composition, physical properties, and application notes for each product series.
Frequently Asked Questions
What is alpha-alumina (α-Al₂O₃)?
What is BET surface area and why does it matter?
What is D50 and how is it measured?
What is the difference between calcined, reactive, and tabular alumina?
What is the difference between cut and polish in alumina polishing?
What packaging options are available?
How do I request a sample or CoA?
Don't see your application?
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