High purity graphite crucibles, also known as machined graphite crucibles, are highly sought after because they are corrosion-resistant, acid- and alkali-resistant, and don’t react with production materials. There are a few differences between high purity graphite crucibles and clay-bonded crucibles.
Production methods and formulations are different. In general, high-purity graphite crucibles are made by CNC machines and contain more than 95% graphite, whereas clay crucibles are made by mixing graphite powder and clay or other materials. Because the graphite content is low, they can’t be called graphite crucibles, but they’re called clay crucibles.
Colors are different. Pure graphite crucibles are black and metallic, and since they’re made from graphite, they have all the graphite properties; clay crucibles are grayish-brown, have no metallic luster, and have a coarse surface. Clay crucibles are coated with moisture-proof lacquer if they are black.
There’s a difference in how it’s used. For clay graphite crucibles, charcoal fires are used at room temperature, while electric furnaces are suitable for pure graphite crucibles.
Costs aren’t the same. Pure graphite crucibles are about – times more expensive than clay melting crucibles.