Why are water-cooled copper crucibles used in titanium melting processes?

Water-cooled copper crucibles are essential in titanium melting processes because of the metal's extreme chemical reactivity when in a liquid state. At high temperatures, molten titanium is highly reactive and will reduce all known refractory materials, meaning it would contaminate itself if melted in traditional crucibles.12

By using a water-cooled copper crucible, the titanium in contact with the crucible walls solidifies rapidly, creating a "skull" or protective layer of solid titanium that prevents the molten metal from touching the copper itself. This technique ensures the purity of the final product by preventing unwanted reactions with the container. This method is utilized in both consumable-electrode arc-melting and cold-hearth melting processes to consolidate titanium sponge into ingots suitable for structural applications.1