how to clean a graphite crucible
Thermionics crucible liners are compatible with many manufacturer’s evaporation sources.
Crucible liners are available in various materials. Carbon graphite and glassy coated carbon graphite are two of the more common materials used. They are popular due to their low cost and favorable thermal properties.
is a fine grain, high density poly-crystalline material with interconnecting porosity. It can be purified to 5 ppm or less.
liners are made from the same high grade carbon as above, then baked in a coated graphite process above 1,400°C to eliminate any porosity in the carbon.
are an alternative to the glassy coated graphite. FABMATE receives an amorphous carbon treatment to provide a hard, abrasion resistant, nonporous surface.
Liners made from these more exotic materials are more expensive and typically limited to special applications.
Maximizing the life of a crucible liner requires careful attention to handling and storage. Never handle liners with bare hands. Liners should be handled with gloves, tongs or finger cots. Graphite, coated graphite and FABMATE liners should not be cleaned with chemicals or solvents of any kind.
Used liners should be stored in a dry, oxygen-free environment.
Proper technique is important, otherwise crucible liners will break due to thermal shock. Breakage, however, can be minimized. In addition, some materials become highly reactive when molten and may alloy to the liner.
The most common cause of crucible liner breakage is thermal shock. Overfilling a liner can cause the evaporant material to “spill over” the liner onto the water-cooled crucible surface. This causes an increased thermal stress across the liner and in most cases will cause it to crack or shatter.
Liners should be filled with evaporant material at a level of no less than 25% volume and no more than 80% volume. Aluminum has a tendency to “wet” most liner materials and requires a reduced maximum charge level of 70%. Aluminum becomes highly reactive when molten and as a result will eventually react with any material.
Hot dip galvanized iron wire Dense Wire Twisted Wire Iron Wire Black Annealed Iron Wire what is wire mesh Decorative Woven Mesh Architectural Wire Mesh Architectural Mesh insulating joint American Standard Railroad Clad Head For Pressure Vessels Galvanized Hog Wire Fence decorative wire mesh supplier Welded Metal Mesh Panels Stainless Steel Welded Metal Mesh Panels