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To manufacture synthetic graphite items, carbon powder and silica are mixed with a binder, such as tar, and baked after being pressed into shape such as that of electrodes or crucibles. [ 8 ] [ 9 ] They are then surrounded with granulated carbon acting as a resistive element that heats them.
The expanded graphite can be used to make graphite foil or used directly as a "hot top" compound to insulate molten metal in a ladle or red-hot steel ingots and decrease heat loss, or as firestops fitted around a fire door or in sheet metal collars surrounding plastic pipe (during a fire, the graphite expands and chars to resist fire ...
The metal is first melted in contact with a carbon source, possibly a graphite crucible inside which the melt is carried out or graphite powder/chunks that are placed in the melt. Keeping the melt in contact with the carbon at a specific temperature dissolves the carbon atoms, saturating the melt based on the metal–carbon binary phase diagram ...
To produce expandable graphite, natural graphite flakes are treated in a bath of acid and oxidizing agent.Usually used oxidizing agents are hydrogen peroxide, potassium permanganate or chromic acid. Concentrated sulphuric acid or nitric acid are usually used as the compound to be incorporated, with the reaction taking place at temperatures of ...
A modern crucible used in the production of silicon ingots via the Czochralski process Smaller clay graphite crucibles for copper alloy melting. A crucible is a container in which metals or other substances may be melted or subjected to very high temperatures.
The crucible process existed in India at the same time that the west- facing technology was operating in Sri Lanka. [38] Excavations of the Yodhawewa (near Mannar) site (in 2018) have uncovered a lower half of a bottom spherical furnace and crucible fragments used to make crucible steel in Sri Lanka during the 7th-8th centuries AD.
A large sample of glassy carbon, with 1 cm 3 graphite cube for comparison A small rod of glassy carbon Vitreous-glassy carbon crucibles. Glass-like carbon, often called glassy carbon or vitreous carbon, is a non-graphitizing, or nongraphitizable, carbon which combines glassy and ceramic properties with those of graphite.
At the time of Dixon's death in 1869, the Joseph Dixon Crucible Company was the largest manufacturer of graphite products in the world. By 1870, The Joseph Dixon Crucible Company was the world's largest dealer and consumer of graphite. By 1872 the Dixon company was making 86,000 pencils a day.