Carbon and Graphite
Both are excellent refractory materials but with good grace oxidize and thus are used merely either in neutral or reducing conditions. Graphite is more stable form of carbon. The amorphous carbon is transformed in crystalline graphite on prolonged heating at about 2500oC. Sublimes at a temperature of 4200oC but Graphite doesn't melt. Graphite and Carbon are highly resistant to acids, alkalies and each solvent except oxidizing ones.
Graphite is utilized at high temperature as rocket nozzle or else nozzle throat insert. The graphite nozzles are coated along with silicon carbide, impregrated with Zr or molybdenum silicate to enhance oxidation resistance. The molten Zr with that graphite surface is impregrated forms zirconium carbide along with good chemical bond along with graphite surface. The outer surface is oxidized to zirconia whereby extra oxidation is stopped.
Graphite and Carbon are utilized in industry in fabricated and non-fabricated forms. Within fabricated forms carbon and graphites are utilized as materials of construction for electrodes, chemically resistant equipment, nuclear reactors and refractory. Carbon and graphite both shapes produced via common techniques are porous. They can be made impervious to fluids by impregnating along with synthetic resin, normally of phenolic type and after that curing resin at high temperature.