Graphite (Flakes, Amorphous)

Amorphous Graphite Powder

S P E C I F I C A T I O N S
Properties Index	Category
	PLUMBAGO Amorph83	PLUMBAGO Amorph85	PLUMBAGO Amorph88	PLUMBAGO Amorph90
Chemical compositions:- Fixed Carbon (%)   ≥ 83 85 88 90 Volatile matter (%) ≤ 3.6 3.4 3.4 3 Moisture (%)          ≤ 3 3 3 3 Screen floating (%) ≤ 10 10 10 10 Packing 1MT bag, 50 kg bag, 25 kg bag

Carbon (C) is a non-metallic element. When no oxygen is present, carbon undergoes sublimation (convert from the solid state directly to vapour state) at or above 3300⁰ C, without melting. If heated in contact with air, however, it easily oxidizes, forming CO & CO₂ gas. carbon is chemically neutral. It is non-wettable with molten metal or slag and is greatly resistant to corrosion. It is also resistant to acid or alkali attack, and is inactive except in contact with strong oxidizing agents.

It has high thermal conductivity, low thermal expansion and good elasticity and so is resistant to thermal spalling. It does not melt or soften easily at high temperatures. Carbon grains cannot be sintered because they are chemically inactive. Accordingly, carbon based refractories often contain clay or other bonding agents to provide some mechanical strength.

Carbon exists both in an amorphous form and in various crystalline forms. Crystalline carbon includes diamond (cubic system) and graphite (hexagonal system). carbon, therefore has three polymorphs. Graphite is available in nature, but is produced artificially as well. Graphite used as a refractory raw material is mostly natural graphite.

The graphite crystal has a layer structure in which the hexagonal rings of carbon atoms are linked with each other in a plane and the planes are piled in parallel. The carbon atoms in the plane are held together by strong covalent bond and the bonds between the layers are held together by weak Van der Waals bond. Therefore well developed graphite crystals in nature easily peel off in layers

Natural graphite occurs in two form, 'vein' or 'flake' graphite with well developed large crystals and amorphous 'graphite' with a microcrystalline structure.

Because graphite has directionally different bond mechanisms (strong bond in the basal plane and weak bond between the layers) it has strongly directional (anisotropic) properties affecting thermal conductivity and coefficient of thermal expansion. This is especially true in vein or flake graphite with well developed crystals. China offers both vein or flake graphite and amorphous graphite.

graphite flakes are widely used in production of carbon blocks, magnesia carbon, alumina-magnesia carbon bricks and variuos monolithics, as source of carbon. It increases the thermal conductivity reducing thermal stress; improves hot strenght; improves non-wettabity with molten metal & slag; and imparts high corrosion resitance. The higher the graphite purity the remarkable is the improvement in the corrosion resistance of the refractories.