Porcelain crucibles are made from a mixture of clay and other minerals, such as feldspar and quartz. They are fired at high temperatures to create a hard, non-porous material that is resistant to heat and chemicals. Porcelain crucibles are typically used for melting metals, salts, and other compounds that do not require extremely high temperatures.
Silica crucibles are made from pure silicon dioxide (SiO2). They are manufactured by fusing quartz sand at high temperatures, which creates a very hard and inert material. Silica crucibles are more resistant to heat than porcelain crucibles, and they can be used for melting materials at temperatures of up to 1800 degrees Celsius. However, silica crucibles are also more expensive than porcelain crucibles.
The main difference between porcelain and silica crucibles is their composition. Porcelain crucibles are made from a mixture of minerals, while silica crucibles are made from pure silicon dioxide. This difference in composition results in different properties, such as melting point, thermal expansion, and chemical resistance.
Porcelain crucibles have a higher melting point than silica crucibles, and they are also less resistant to thermal expansion. This means that porcelain crucibles are more likely to crack or break when they are heated or cooled rapidly. Silica crucibles, on the other hand, are more resistant to thermal expansion, and they can be used for high-temperature applications.
Porcelain crucibles are also less chemically resistant than silica crucibles. This means that porcelain crucibles are more likely to react with the materials that they are being used to melt, which can contaminate the samples. Silica crucibles, on the other hand, are very chemically resistant, and they are less likely to react with the materials that they are being used to melt.
In general, porcelain crucibles are less expensive than silica crucibles. However, the best choice of crucible for a particular application will depend on the specific requirements of the experiment.