Choosing the right crucible material determines whether your sample stays pure or reacts with the vessel. This guide compares Scuvette's four high-purity crucible ceramics — alumina (Al₂O₃), zirconia (ZrO₂), yttria (Y₂O₃) and magnesia (MgO) — across working temperature, chemical compatibility and typical applications, so you can select the right crucible for your melt.
| Property | Alumina (Al₂O₃) | Magnesia (MgO) | Zirconia (ZrO₂) | Yttria (Y₂O₃) |
|---|---|---|---|---|
| Max service temperature | Up to 1600°C | Up to 2200°C | Up to 2300°C (inert/reducing) | ~2400°C in air (higher in inert/reducing) |
| Typical purity | 99% (95–99.7% available) | 99% | Calcia-stabilized | 95% |
| Best for alkaline melts | Poor — reacts with strong alkalis | Excellent | Good (resist wetting by metals) | Excellent (also fluorides, alkali metals, rare-earth) |
| Thermal-shock resistance | Moderate | Lower — heat slowly | Good (best of the three) | — |
| Relative cost | Lowest | Higher | Highest | Premium |
Alumina is the most widely used crucible ceramic because it is cost-effective and chemically stable across a broad range of neutral, oxidizing and acid environments. With a long-term service temperature up to 1600°C, it covers the majority of everyday high-temperature work: ceramic sintering, ash determination, metal melting and thermal analysis (TGA/DSC).
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Magnesia crucibles are the go-to when you are melting strongly alkaline or alkaline-earth materials, refining non-ferrous metals, or working with slags and fluxes that would attack alumina. Rated up to 2200°C, magnesia resists basic melts that destroy other oxides. Its trade-offs are lower thermal-shock resistance (heat it gradually) and a higher price.
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Calcia-stabilized zirconia crucibles are engineered for the most demanding work: melting precious metals (platinum, gold, palladium, silver), specialty alloying and crystal growth. Zirconia resists wetting by molten metals, offers the best thermal-shock resistance of the three, and is rated up to 2300°C in inert or reducing atmospheres. It is also the most expensive option.
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Start from your melt chemistry and process temperature. For neutral or oxidizing general high-temperature work, 99% alumina is the cost-effective default. For precious-metal or alloy melting, choose calcia-stabilized zirconia. For highly reactive melts — fluorides, alkali metals, rare-earth compounds — or when trace contamination must be avoided, choose 95% yttria. For alkaline melts, reactive metals and molten salts, choose magnesia. Confirm compatibility with our team for unusual melts.
Alumina (up to 1600°C) suits everyday sintering, calcination and ash testing in neutral or oxidizing atmospheres. Zirconia (up to 2300°C in inert/reducing) is for precious-metal melting and specialty alloying because it resists wetting by molten metals and has the best thermal-shock resistance. If your process runs hotter than 1600°C or involves molten noble metals, move to zirconia.
Choose 95% yttria when the melt is highly reactive — fluoride salts, alkali metals, rare-earth compounds — or when even trace contamination from the vessel must be avoided. Yttria resists these melts far better than alumina or zirconia, and is rated up to ~2400°C in air.
Magnesia (MgO) crucibles are the right choice for alkaline melts, reactive metals and molten salts. Alumina and zirconia both react with strong alkaline melts and fluoride fluxes, so avoid them for those processes.
Long-term service limits: alumina up to 1600°C, magnesia up to 2200°C, zirconia up to 2300°C (inert/reducing), and yttria up to ~2400°C in air (higher in inert/reducing atmospheres). Confirm the exact limit for your process atmosphere with our team.
No. Alumina is stable in neutral, oxidizing and most acid environments but reacts with strong alkaline melts and fluoride fluxes. Magnesia is stable against alkaline and many reactive-metal melts but is attacked by acids. Pick the crucible for the dominant chemistry of your melt.