needle cokeNeedle coke is a kind of high-quality coke with obvious fibrous texture, low thermal expansion coefficient and easy graphitization. When the coke is broken, it can split into elongated particles according to the texture (the aspect ratio is generally above 1.75). An anisotropic fibrous structure can be observed under a polarized light microscope, so it is called needle coke.

The anisotropy of the physical and mechanical properties of needle coke is very obvious. It has good electrical and thermal conductivity parallel to the long axis of the particles, and has a low thermal expansion coefficient. During extrusion, most of the long axes of the particles are arranged in the extrusion direction.
Therefore, needle coke is the key raw material for the manufacture of high-power or ultra-high-power graphite electrodes. The resulting graphite electrodes have low resistivity, low thermal expansion coefficient, and good thermal shock resistance.

Needle coke is divided into oil-based needle coke produced with petroleum residue as raw material and coal-based needle coke produced with refined coal pitch raw material.