Thomas Brand: Crucibles

Highly resistant to most reagents Soluble in hydrofluoric acid Withstands temperatures up to 900°C Low form crucible is 0.89 mm thick zirconium. Will begin to oxidize with prolonged exposure to air at temperatures above 550°C. Not recommended for use with fluoboric or fluorosilic acid....

Nickel forms an adherent oxide film that provides its corrosion resistance up to temperatures around 600°C. It's highly resistant to alkalis and most acids, however, it is attacked by oxidizing acids like nitric and by salt solutions containing oxidizing species.